An illustrated catalogue of macroscopic subfossils from late-Pleistocene and Holocene westland deposits in northern Indiana.

ABSTRACT. Subfossils from 16 holocene wetlands in northern Indiana were described and illustrated. A summary of the relative abundance, stratigraphic occurrence, chronology, and frequency of each taxon was presented. Approximately 57 taxa representing algae, vascular plants, mollusks, insects, and vertebrates were recorded in the survey. The subfossils range in age from recent (within 50 years before present) to 15,910 [+ or -] 90 years before present.

**********

Recognizing the great value of peatlands and other wetland deposits as natural museums, Potzger (1936) remarked,

In more recent times the Pleistocene not only left a trail of tell-tale relic colonies of northern plants here in Indiana, but also made its contributions to the fossil records by depositions in bogs and slowly-forming topographic features, where life records are neatly stored away as in a vast archive, preserving the story of the day when they were living forms, and linking the past to the present, partially interpreting for us the plant and animal world of today.

These subfossil remains, preserved in the wetland deposits of the region, include both microfossils, such as pollen and diatoms, and macroscopic remains, including leaves, seeds, fish scales, turtle shells, and a variety of other remains.

Although the fossil pollen from Indiana's Holocene peat deposits has received much attention, especially in the first half of the 20th century [see Swinehart (1997) for review], relatively few studies have focused on the macroscopic subfossils of Indiana's wetland deposits. Most studies on macroscopic subfossils have centered on individual sites (Potzger 1936; Friesner & Potzger 1946; Whitehead et al. 1982; Jackson et al. 1986; Swinehart & Starks 1994; Swinehart 1995a, b), and many of these were associated with the remains of ice-age megafauna. More recently, Swinehart & Parker (2000) conducted a comprehensive study of the subfossil biota of the peatlands of northern Indiana. Additionally, the Indiana State Museum has recently placed a higher priority on detailed studies of macroscopic plant subfossils associated with ice-age mammal remains (Swinehart 1996; Swinehart & Richards 2001), whereas previously these were often neglected (Richards et al. 1987; Hunt & Richards 1992).

With increased attention being devoted to macroscopic subfossils for palaeoenvironmental reconstructions, there is a need to develop resources that facilitate identification of subfossils and a need to record the stratigraphic occurrence and frequency of individual species in a given region. Determining the identity of subfossil biota is complicated by the fact that most remains are only fragments or reproductive propagules of organisms. Because most dichotomous keys and field guides focus on the descriptions of entire organisms, few resources exist that allow identification of depauperate subfossil fragments representing a variety of taxonomic phyla.

This paper summarizes the subfossil assemblages of 16 wetlands studied by the author during the past ten years. The objectives are to describe and illustrate subfossils recovered from northern Indiana wetlands and summarize their relative abundance, stratigraphic occurrence, chronology, and frequency.

METHODS

Subfossils are here defined as (1) remains of once living organisms that are composed, at least in part, of their original organic constituents, or (2) inorganic material of biotic origin that has not yet been lithofied (i.e., mollusc shells, Chara tests). With the exception of Potamogeton achenes which were determined using the manuscript by Jessen (1955), subfossil seeds and achenes were identified using the text by Montgomery (1977). Mosses were identified with the assistance of Crum & Anderson (1981) and Janssens (1983); molluscs with the assistance of Harmen & Berg (1971). Sphagnum remains were not identified to species. Questionable subfossil material that seemed referable to a known taxon is preceded by the Latin abbreviation "cf." (conferre). Representative subfossils from each wetland were placed in vials with a 60% solution of ethanol. Voucher specimens were placed in the private museum of the author at Hillsdale College and are available for examination. Specimens were hand drawn from actual subfos sil material by the author with the aid of dissecting scope and ruler.

Developmental stages of the peatlands were based on assemblages of subfossils that denoted seral stage and/or structural characteristics of the respective ecosystems and were determined by visual inspection of subfossil diagrams (see Swinehart & Parker 2000; Swinehart & Richards 2001).

A list of the sites and their general locations is presented in Table 1. Several sediment collection methods were used among the 16 sites. The general stratigraphy of each site is summarized in Fig. 1.

Ice-age mammal localities.--(Aker, Shafer, and Wilkinson deposits). A sump was excavated near the fossil mammal bones to drain water from the bone bed. Once the standing water was drained, disturbed muck was carefully removed from the site by hand, placed into buckets, and washed through a 1.2 mm mesh screen to recover possible hone fragments and other subfossils. The site was then divided into 2 [m.sup.2] units. Sediment from each unit was removed at 10 cm intervals from the top of the bone-bed to the bottom of the wetland deposit. This bulk material was washed through 1.2 mm mesh screens for recovery of macroscopic subfossils and small bones. In addition to bulk samples, smaller sediment samples were taken for the identification and quantification of smaller subfossils. A 50 [cm.sup.3] plastic container was pushed into the vertical profile of sediment adjacent to the bone bed at 10 cm intervals, beginning at the wetland surface and extending to the glacial drift at the bottom of the deposit.

Subfossils taken from screened bulk material were identified and counted. Additionally, the smaller (50 [cm.sup.3]) sediment samples were carefully rinsed through a 0.2 mm mesh screen. The recovered subfossils were then identified and counted.

Celery Bog.--An Osterburg hydraulic piston corer mounted on an all-terrain vehicle was used to collect a 10 m deep core with a diameter of 10 cm. The core extended from the surface of the wetland to glacial till at the bottom. Sections of the core, collected in 3 meter-long metal sleeves, were brought to the laboratory for analysis. The metal sleeves containing the cores were hand-sawed into 10 cm sections. The sediment from each 10 cm section was examined for identifiable subfossil remains.

A standard 20 ml volume was taken from each interval and gently rinsed through a 0.4 mm mesh sieve. The material remaining in the sieve was placed in a petri dish and examined under a dissecting microscope for identification and quantification of macroscopic subfossils.

Bristol Fen & Tamarack Bog.--Sediments in Bristol Fen were collected manually with a post-hole excavator at 15 cm intervals. Blocks of peat from each depth interval were rinsed with water on a 1 mm mesh screen. Rinsed material was sorted by hand. Sediments from Tamarack Bog were recovered using a 2.5 cm diameter Hillar corer. Sediments from 20-25 cm intervals were rinsed, and subfossils were identified with the aid of a dissecting microscope. Subfossils from Bristol Fen and Tamarack Bog were not counted.

Remaining sites.--Each site was systematically probed using metal rods. Coring was conducted at the deepest probe location in each peatland. A modified Hiller corer with a chamber diameter of 5 cm was used to collect sediments. Cores were sectioned into 25 cm lengths and placed into plastic bags. A standard 20 [cm.sup.3] volume was taken from each interval and gently rinsed through a 0.4 mm mesh sieve. The material remaining in the sieve was placed in a petri dish and examined under a dissecting microscope for identification and quantification of macroscopic subfossils. The remaining sediment from each sampling interval was also rinsed through a 0.4 mm mesh sieve. The material was then placed into a white enamel pan and examined for large, infrequent subfossils such as bones, large seeds and leaves that might not have been represented in the 20 [cm.sup.3] subsamples.

Radiocarbon dating.--Selection of material at different depths for radiocarbon ([C.sup.14]) dating was based on the developmental stages represented in subfossil diagrams (see Swinehart & Parker 2000; Swinehart & Richards 2001). Whenever possible, aquatic and wetland bryophytes were excluded from the radiocarbon samples to reduce the potential for carbon loading. The samples were treated using the Acid-Base-Acid method and were analyzed by accelerator mass spectrometry at the Purdue University Rare Isotope Measurement (PRIME) Laboratory. All results are reported in years before present (ybp) and have been corrected to Delta [C.sup.13] of -25PDB.

Although radiocarbon dates are not available for all depths in each peatland, most major stratigraphic units have been dated (Fig. 1). Because of the cumulatively large number of radiocarbon dates and because the dates generally occur at the strata where major changes in biota occurred, it was possible in most cases to get a general idea of the earliest dated records for each taxon among the sites in northern Indiana. For species that are currently extant in Indiana, only the oldest radiocarbon date was reported for the respective taxa. For species that are currently extinct in Indiana, both the oldest and youngest available radiocarbon dates are reported.

RESULTS

Approximately 57 taxa were represented in the survey of macroscopic subfossils from the 16 Indiana wetlands (Table 2, Figs. 2-101). The subfossils range in age from recent (within 50 ybp) to 15,910 [+ or -] 90 ybp. The following is a list and description of each taxon including a summary of the current habitat, typical condition of the subfossils, and the stratigraphic occurrence of each taxon.

Kingdom Plantae

Division Thallophyta

Class Chlorophyceae 

Order Charales 

Family Characene

Chara sp.: (Figs. 2, 3). Habitat: Springs, ponds, and lakes with highly alkaline waters, commonly forming dense mats on sandy or marly bottoms; in open areas and protected bays, often in association with water lilies. Although most common in shallow water, plants may be found at depths of several meters. Description: Subfossil oogonia (Fig. 2) are usually slightly less than 0.5 mm; oval; dark brown to black in color, generally opaque when entire; raised spiraling ridges separated by concave hollows; spirals unravel in a ribbon-like fashion when structure is damaged. Subfossil thalli (Fig. 3) are small fragments usually less than 4 mm in length; gray; lime-covered; cylindrical and sulcate; cell walls often visible at breakage points or where lime has been scraped away. Stratigraphy: Thalli comprised a large percentage of the marl in Kiser Lake Fen, Kosciusko County, Indiana, and were found throughout the marl stratum; vegetative thalii never found in organic sediments. Oogonia frequent in the early limnic sedi ments of some peatland basins, usually absent in the marsh, fen, and bog strata. Chronology: The oldest dated record is 12,590 [+ or -] 60 ybp (Aker Mastodont Locality). Frequency: 38%. Abundance: Frequent where found, although many of the marls lack identifiable remains of thalli.

Division Bryophyta

Subdivision Musci

Class Sphagnopsida

Order Sphagnales

Family Sphagnaceae

Sphagnum spp.: (Figs. 4-6). Habitat: Peatlands; in carpets or lawns and occasionally developing hummock/hollow complexes in acid conditions, restricted to isolated hummocks in more neutral to alkaline environments. Description: Leaf thalli (Fig. 4) light brown; composed of large, rhomboidal, hyaline cells bordered by narrow, linear cells (chlorophyllose when living); hyaline cells usually bearing large spherical or elliptical pores (Fig. 5). Occasionally, leaf thalli found attached to stem thalli (Fig. 6), but only in the uppermost, more recent sediments. Stratigraphy: Generally restricted to the upper 2-3 m of sediment. Chronology: The oldest dated record is < 9530 [+ or -] 90 ybp (Celery Bog). Frequency: 56%. Abundance: Extremely frequent where found, often comprising more than 90% of the peat.

Class Bryopsida

Order Bryales

Family Meesiaceae

Meesia triquetra: (Figs. 7-9). Habitat: In wet, highly alkaline, often marly areas; open fens or forested peatlands, mostly in boreal climates. No extant populations have been reported from Indiana. Description: Subfossils found as well-preserved fragments (Fig. 7) up to 40 mm in length; stems often radiculose; radicles dark reddish-brown in color; leaves (Fig. 8) golden to dark brown in color, keeled above shoulder, distinctly serrulate at margins (Fig. 9) from shoulders to the acute apex, cells rhomboidal to rectangular; costa pronounced, extending into the acumen. Stratigraphy: Found at the interface between fen peat and Sphagnum bog peat, always associated with Calliergon trifarium but in lesser quantity. Chronology: The youngest dated record is 59 [+ or -] 80 ybp (Little Arethusa Bog), and the oldest dated record is 4110 [+ or -] 100 ybp (Dutch Street Bog). Frequency: 31%. Abundance: Frequent where found; occurs as discrete strands.

Order Hypnobryales

Family Thuidiacene

Thuidium delicatulum: (Figs. 10-12). Habitat: Moist soil and humus, most commonly on rotting logs in swamps or wet woodlands. Description: Fragments (Fig. 10) small, twice pinnate, dark brown in color, well preserved; primary branch leaves (Fig. 11) more or less ovate, with an acute apex (Fig. 12); costa pronounced, extending to the lower acumen, margins papillose-serrulate. Stratigraphy: Two fragments from basal sediments of Little Arethusa Bog. Frequency: 6%. Abundance: Extremely rare.

Family Amblystegiaceae

Campylium stellatum: (Figs. 13-15). Habitat: In open, wet areas of highly alkaline marshes and fens (Crum & Anderson 1981). Also found in swamps and on wet banks (Welch 1957). Description: Small fragments (Fig. 13) mostly less than 20 mm in length, light brown in color; leaves (Fig. 14) broad at base, narrowing to a slender, acute apex, entire, arising from stem at an acute angle, then spreading away from stem near shoulder; costa present, forked, one extension being longer than the other, often extending to midleaf; alar cells (Fig. 15) conspicuous, concentrated at leaf margin and not extending to costa. Stratigraphy: In sapric or hemic peat of Binkley Fen, also in silt at Wilkinson Giant Beaver Locality. Chronology: The oldest dated record is greater than 11,990 [+ or -] 90 ybp (Wilkinson Giant Beaver Locality). Frequency: 13%. Abundance: Rare where found, occurs as single strands.

Drepanocladus aduncus: (Figs. 16-19). Habitat: Wet calcareous areas including swamps marshes, sloughs, lakeshores, and sluggish streams. Most common in fens and mineral-rich lagg waters of bogs, often emergent and sometimes submergent. Description: Well preserved fragments (Fig. 16) up to 100 mm in length, light brown to reddish-brown in color; leaves (Fig. 17) entire, ovate-lanceolate, narrowing to a slender, channeled acumen, falcate, occasionally but not always secund, sometimes spreading in a form similar to Amblystegium riparium; costa pronounced, extending above midleaf; upper median cells of leaf (Fig. 18) rhomboidal-linear; alar cells (Fig. 19) somewhat conspicuous, extending from leaf margin to within three rows of cells from the costa, sometimes difficult to observe, often retained on stem when leaf is torn away. Although not characteristic of the species, the walls of the alar cells on many of the specimens are dark yellow-brown in color. Stratigraphy: Beginning at the upper reaches of limnic sedim ent and eventually forming peat, often replaced by Calliergon trifarium and Meesia triquetra before Sphagnum peat dominates within the top 2-3 m of the profile. Chronology: The oldest dated record is 13,170 [+ or -] 170 ybp (Svoboda Fen). Frequency: 81%. Abundance: Extremely abundant where found, often forming pure strata of entangled strands.

Scorpidium scorpioides: (Figs. 20-22). Habitat: Open fens, often submergent or emergent (Crum & Anderson 1981). Description: Small fragments (Fig. 20) mostly less than 10 mm in length, light brown in color, more or less prostrate; leaves (Fig. 21) oblong-ovate, somewhat imbricate; costa lacking; cells at insertion enlarged; alar cells (Fig. 22) somewhat inconspicuous. Stratigraphy: Deep in the hemic peat of Svoboda Fen. Chronology: The oldest record is 13,170 [+ or -] 170 ybp (Svoboda Fen). Frequency. 6%. Abundance: Extremeley rare.

Calliergon stramineum: (Figs. 23-25). Habitat: Open, rich fens and sedge meadows, laggs (Crum & Anderson 1981). Extant populations have not been reported from Indiana. Description: Small shreaded fragments (Fig. 23) less than 10 mm in length, reddish-brown; leaves (Fig. 24) oblong, entire, imbricate, decurrent, more or less spreading; costa pronounced, extending to the apex; walls of cells at leaf base thickened; alar cells (Fig. 25) conspicuous, concentrated at the leaf margin and not extending to the costa. Stratigraphy: In hemic peat (fen stratum) between limnic sediments and Sphagnum peat. Chronology: The most recent dated record is 2835 [+ or -] 80 ybp (Ropchan Memorial Bog), and the oldest record is greater than 3680 [+ or -] 80 ybp (Little Chapman Bog). Frequency: 25%. Abundance: Rare where found; occurs as single small fragments.

Calliergon trifarium: (Figs. 26-29): Habitat: Highly alkaline, wet-fen habitats, often found as strands among other mosses and sedges (Crum & Anderson 1981). Extant populations have not been reported from Indiana. Description: Well preserved fragments (Fig. 26) up to 30 mm in length, terete, light brown in color; leaves (Fig. 27) elliptic to oblong, entire, imbricate, crowded and apressed at base of stem, somewhat loose spreading near tips (Fig. 28); costa present, about two-thirds the length of the leaf; alar cells (Fig. 29) enlarged, extending from leaf margin to costa. Stratigraphy: Found at the interface between fen peat (dominated by Drepanocladus aduncus) and Sphagnum peat. Almost always associated with Meesia triquetra. Chronology: The most recent dated record is 45 [+ or -] 80 ybp (Little Chapman Bog), and the oldest dated record is 4010 [+ or -] 80 ybp (Burket Bog). Frequency: 44%. Abundance: Extremely frequent where found, often comprising a large portion of the total volume of peat.

Family Polytrichaceae

Polytrichum strictum: (Figs. 30, 31). Habitat: On the dry tops of Sphagnum hummocks in bogs. Description: Well preserved fragments (Fig. 30) up to 40 mm in length, auburn in color; leaves (Fig. 31) straight and erect, base broad, becoming lanceolate and in-folded above shoulders, ending in a toothed awn, cells at shoulder laterally elongate and cramped; costa pronounced, excurrent, bearing lamellae. Stratigraphy: In upper layers of Sphagnum peat stratum in Yost Bog, Lagrange County, Indiana. Frequency: 6%. Abundance: Frequent in Yost Bog as individual strands in Sphagnum peat.

Division Spermatophyta

Subdivision Gymnospermae

Order Coniferales

Family Pinaceae

Picea glauca: (Figs. 32, 34). Habitat: Well-drained coniferous swamps, lakeshores and stream borders, mixed forests (Voss 1972), and occasionally in peatlands; mostly in boreal climates. Extinct in Indiana. Description: Cones (Fig. 32) well preserved, elongate 30-50 mm in diameter; seeds intact within axles of scales; leaves (Fig. 34) fragmented, poorly preserved, mostly apices, thick, four-angled in cross-section, not distinguished from P. mariana. Stratigraphy: In deeper sediments of silt and especially marl deposits. Chronology: The most recent dated record is 11,240 [+ or -] 80 ybp (Wilkinson Giant Beaver Locality), and the oldest dated record is 15,540 [+ or -] 70 ybp (Shafer Mastodont Locality). A piece of spruce wood dating 15,910 [+ or -] 90 ybp from the basal sediments of Celery Bog is probably Picea glauca, but the specific species cannot be determined definitively. Frequency: 25%. Abundance: Cones and leaves infrequent where found.

Picea mariana: (Figs. 33, 34). Habitat: In wet, often nutrient-poor areas such as swamps, low lakeshores, and bogs. In the southern portions of its range, it is restricted entirely to bogs. Extinct in Indiana. Description: Cones (Fig. 33) well-preserved, ovateobovate, 15-30 mm in length; seeds intact within axels of scales; leaves (Fig. 34) fragmented, poorly preserved, mostly apices, thick, four-angled in cross-section, not distinguished from P. glauca. Stratigraphy: In peaty marl. Chronology: The most recent dated record is 11,460 [+ or -] 450 ybp (Bristol Fen), and the oldest dated record is 15,590 [+ or -] 60 ybp (Aker Mastodont Locality). Frequency: 19%. Abundance: Cones and leaves infrequent where found.

Larix laricina: (Figs. 35-37). Habitat: Swamps, lakeshores and stream borders, fens, and bogs. Restricted to peatlands in the southern portions of its range. Pioneering opportunists, they prefer open areas where competition for light with other trees is minimal. Description: Cones (Fig. 35) poorly preserved, fragile, stalked; twigs (Fig. 36) bearing woody spurs with many annual whorls of leaf scars; spurs seem to be more decay resistant due to dense xylem; leaves (Fig. 37) well preserved at least in hemic and fibric peat, compressed, brown in color, blades translucent when viewed under lighted dissecting scope, gradually thinning from midrib to leaf margin. Stratigraphy: Most common in brown moss peats, less common in Sphagnum. Abundant Larix macrofossils were found only in peatlands that are currently dominated by tamarack (with the exception of the Aker, Wilkinson, and Shafer localities which have been anthropogenically altered), suggesting that tamarack bogs may have a unique developmental history and ecol ogy. Chronology: The oldest dated record is 15,540 [+ or -] 70 ybp (Shafer Mastodont Locality). Frequency: 56%.

Abundance: Leaves frequent where found; cones and twigs rare; spurs were abundant in limnic sediments at the Shafer Mastodont locality, infrequent to rare at other localities.

Abies balsamea: (Fig. 38). Habitat: Coniferous and mixed forests; occasionally in cedar swamps, fens, and bogs. Description: Leaves (Fig. 38) often well preserved, though seldom entire, dark brown, thick, opaque even when observed with a lighted dissecting scope, somewhat revolute near petiole, in-folded margins compress to a thickening along the majority of the blade, midrib raised on both sides. Stratigraphy: Lower strata; most common in marl. Chronology: The only dated record is 15,910 ybp (Celery Bog). Frequency: 19%. Abundance: Leaves frequent where found; cones have not yet been found and are likely very rare in lake and wetland deposits.

Subdivision Angiospermae

Class Monocotyledoneae

Order Najadales

Family Potamogetonaceae

Potamogeton praelongus: (Fig. 39). Habitat: Lakes, in water up to 7 m (Voss 1972), in clear waters, often associated with Ceratophyllum demersum, Najas flexilis, Potamogeton amplifolius, P. gramineus, P. natans, P. pectinatus, and P. robbinsii (Swink & Wilhelm 1994). Description: Opercle of achene keeled and winged, ventral margin wavy, beak ventral. Stratigraphy: In marl, Wilkinson Giant Beaver Locality, Whitley County. Abundance: Infrequent to frequent where found.

Potamogeton obtusifolius: (Fig. 40). Habitat: Lakes and ponds. Description: Achene (Fig. 40) bearing two projections at base, opercle more or less keeled, sides convex. Stratigraphy. In marl, Wilkinson Giant Beaver Locality, Whitley County. Abundance: Infrequent to frequent where found.

Potamogeton pusillus: (Fig. 41). Habitat: Lakes and ponds and occasionally quiet waters of streams, in shallow waters less than 2 m (Voss 1972), prefers calcareous waters, often associated with Elodea canadensis, Myriophyllum exalbescens, Najas flexilis, Nuphar advena, Potamogeton natans, P. nodosus, P. pectinatus, P. zosteriformis, and Vallisneria americana (Swink & Wilhelm 1994). Description: Small, well-preserved, relatively smooth achenes (Fig. 41), yellow-brown in color. Stratigraphy: Limnic sediments, including marl. Chronology: The oldest dated record is 15,540 [+ or -] 70 ybp (Shafer Mastodont Locality). Abundance: Infrequent to frequent where found.

Family Najadaceae

Najas flexilis: (Fig. 42). Habitat: Extremely common in lakes, ponds, marshes, sloughs, rivers and streams. Also found on soft bottoms of open waters in peatlands. Commonly associated with Ceratophyllum demersum, Elodea canadensis, Lemna minor, Myriophyllum exalbescens, Potamogeton foliosus, P. natans, P. nodosus, P. pectinatus, and Vallisneria americana (Swink & Wilhelm 1994). Fruits abundantly. Description: Achenes (Fig. 42) extremely well preserved, fusiform, glossy, mostly reddish in color but varying from gray to light brown or yellowish, surface slightly alveolate when viewed under magnification. Stratigraphy: Characteristic of limnic sediments, in silt, clay, gyttja, and marl. Chronology: The oldest dated record is 15,540 [+ or -] 70 ybp (Shafer Mastodont Locality). Frequency: 94%. Abundance: Extremely frequent, probably the most common and numerous macrofossil in aquatic sediments. Found in almost every deposit, including humified material. Present in similar abundance in recent lake sediments of Bear Lake, Noble County, Indiana, Spotted Turtle Pond, Elkhart County, Indiana, and other extant, eutrophic lakes and ponds.

Family Cyperaceae

Eleocharis sp.: (Fig. 43). Habitat: Lake and pond shores, stream borders, bogs and fens, marshes, swamps, and wet depressions. Description: Achenes (Fig. 43) small, less than 2 mm, black in color, glossy, somewhat alveolate. Stratigraphy: Hemic peat. Chronology: The oldest dated record is 12,070 [+ or -] 50 (Aker Mastodont Locality). Frequency: 19%. Abundance: Rare where found.

Scirpus subterminalis: (Figs. 44, 45). Habitat: In water to 1 m in lakes, ponds, peatland pools, and rivers; on sand, muck, marl, or peat (Voss 1972); usually calcareous habitats often with Scirpus validus (Swink & Wilhelm 1994). Description: Achenes (Fig. 44) well preserved, more or less elliptical in long section tapering abruptly to a sharp style, three-angled/triangular in cross section (Fig. 45), 6 bristles bearing antrorsed teeth. Stratigraphy: In hemic peat of Yost Bog. Frequency: 6%. Abundance: Infrequent where found.

Scirpus acutus-type: (Figs. 46, 47). Habitat: In shallow water or wet areas around lakes, ponds, marshes, and flowing waters; also found in fens and marl flats. S. validus which has a similar achene grows in similar habitats. Description: Achenes (Fig. 46) well-preserved although bristles often lacking, black in color, tear-shaped in long section ending in a short pointed style, oval and compressed in cross section (Fig. 47); bristles bearing retrorsed teeth. Stratigraphy: Beginning at the transition from limnic sediments to marsh and fen sediments and may occur throughout the fen stratum. Generally absent from Sphagnum peat. Chronology: The oldest dated record is 12,590 [+ or -] 60 ybp (Aker Mastodont Locality). Frequency: 81%. Abundance: Variable from infrequent to frequent where found; extremely frequent at the Wilkinson Giant Beaver locality, Kosciusko County, Indiana.

Carex cf. pseudo-cyperus: (Figs. 48, 49). Habitat: In shallow water or wet areas around lakes, ponds, marshes, and streams; also in swamps and bogs. Description: Achenes (Fig. 48) well preserved, lacking bristles, obovate in long section ending in a retrorsed cylindrical style, three-angled/triangular in cross-section (Fig. 49), surface somewhat alveolate. Stratigraphy: In sedge peat in Blueberry Bog, Elkhart County, Indiana. Chronology: The only dated record is 2190 [= or -] 80 ybp (Blueberry Bog). Frequency: 6%. Abundance: Infrequent where found.

Dulichium arundinaceum: (Fig. 50). Habitat: Marshes, fens, and mineral-rich areas of bogs; often forming treacherous floating mats. Description: Achenes (Fig. 50) more or less fusiform, ending in a long narrow style, light brown in color, glabrous, somewhat translucent; bristles bend toward style and lack teeth. Stratigraphy: In fen strata. Chronology: The only dated record is 1850 [+ or -] 80 ybp (Little Chapman Bog). Frequency: 19%. Abundance: Rare where found.

Fuirena pumila: (Fig. 51). Habitat: Mud flats around lakes and ponds; floating mats of fens. Description: Fruits well preserved, light brown; Achenes (Fig. 51) more or less fusiform in long section, three-angled/triangular in cross section, stalked, ending in a short acute style; bristles three, bearing retrorsed teeth; bracts three, thickened, chordate with long, acuminate tips. Stratigraphy: In lower layers of Sphagnum peat, Yost Bog, Lagrange County, Indiana. Frequency: 6%. Abundance: Infrequent where found.

Class Dicotyledonaceae

Order Ranunculales

Family Ceratophyllaceae

Ceratophyllum demersum: (Figs. 52-53). Habitat: Submergent in quiet waters of lakes, ponds, sloughs, and streams. Prefers calcareous waters (Swink & Wilhelm 1994). Description: Leaves (Fig. 52) well preserved, light brown with dark brown spots, translucent, flattened from compression by sediment, often forked, bearing several teeth on lower margin; achenes (Fig. 53) oblong with two protruding spines and a long thin style, bearing many light brown scaly protrusions on main body. Stratigraphy: Restricted to the lower layers of limnic sediment; associated with Najas flexilis and occasionally with other aquatics such as Potamogeton spp. Chronology: The oldest dated record is 13,170 [+ or -] 170 ybp (Svoboda Fen). Frequency: 50%. Abundance: Leaves frequent to extremely frequent where found; achenes rare, not always present with leaves.

Family Nymphaceae

Nuphar advena: (Figs. 54, 55). Habitat: Emergent in quiet waters of lakes, ponds, rivers, and streams. Often associated with Brasenia schreberi, Ceratophyllum demersum, Lemna minor, Nymphaea tuberosa, and Pontedaria cordata. Description: Seeds (Fig. 54) obovate, usually black but occasionally brown, auburn, or yellowish in color, glossy, commonly bearing a slight "keel" (Fig. 55) but not as pronounced as in Nymphaea odorata. Stratigraphy: Transitional stratum between limnic sediments and fen peat; occasionally found well within fen and bog strata, presumably from remnant plants surviving within an advancing floating mat. Chronology: The oldest dated record is 11,990 [+ or -] 90 ybp (Wilkinson Giant Beaver Locality). Frequency: 50%. Abundance: Infrequent to rare where found.

Nymphaea odorata-type: (Fig. 56). Habitat: Emergent in quiet, shallow water of lakes, ponds, rivers and streams. Often associated with Brasenia schreberi, Ceratophyllum demersum Lemna minor, Najas flexilis, Nuphar advena, and Pontedaria cordata. Description: Seeds (Fig. 56) oblong , slightly keeled, black in color, dull. Stratigraphy: Transitional stratum between limnic sediments and fen peat; occasionally found well within fen and bog strata, presumably from remnant plants surviving within an advancing floating mat. Chronology: The oldest dated record is 11,990 [+ or -] 90 ybp (Wilkinson Giant Beaver Locality). Frequency: 31%. Abundance: Infrequent to rare where found.

Brasenia schreberi: (Figs. 57, 58). Habitat: Quiet ponds and lakes, usually in soft, acid waters (Voss 1972); commonly associated with Elodea canadensis, Lemna minor, Myriophyllum exalbescens, Nuphar advena, Nymphaea odorata, Polygonom amphibium, Pontedaria cordata, Potamogeton pectinatus, Spirodela polyrhiza, and Utricularia vulgaris (Swink & Wilhelm 1994). Description: Seeds (Fig. 57) oblong, bearing conspicuous micropyle at narrow end, opposite end is papillose; seed coat thick, woody, comprising nearly 20--25% of the diameter of the seed; empty individuals are dark brown to black in color, some specimens are reddish in color due to the reflectance of white endosperm within the seed; examination of endosperm from seeds shows cells intact; embryo present (Fig. 58); probably viable. Stratigraphy: Most common in the transitional marsh sediments between the limnic stratum and fen peat; usually with other emergents such as Nuphar advena; specimens bearing endosperm have been found to depths up to 6 m; as many a s 20% of specimens contain endosperm in some deposits. Chronology: The oldest dated record is 11,240 [+ or -] 80 ybp (Wilkinson Giant Beaver Locality). Frequency: 56%. Abundance: Infrequent to rare, although it is not uncommon to find 40-50 seeds in a 300 [cm.sup.3] volume of sediment.

Order Sarraceniales

Family Sarraceniaceae

Sarracenia purpurea: (Fig. 59). Habitat: Bogs and fens. Description: Seeds (Fig. 59) poorly preserved, somewhat kidney shaped, brown in color, bordered on one side by a compressed "keel." Stratigraphy: In Sphagnum peat. Chronology: The only dated record is 1140 [+ or -] 90 ybp (Dutch Street Bog). Frequency: 6%. Abundance: Extremely rare; only one specimen found in Dutch Street Bog.

Order Sapindales

Family Balsaminaceae

Impatiens capensis: (Fig. 60). Habitat: Moist woods, swamps, floodplains, marshes, fens, lakeshores. Description: Seeds (Fig. 60) oblong in long section, compressed-oblong in cross section, black in color, bearing a narrow winged margin; seed bisected by a narrow ridge. Stratigraphy: In hemic peat of Svoboda Fen. Frequency: 6%. Abundance: Extremely rare; description based on a single specimen.

Order Myrtales

Family Haloragidaceae

Myriophyllum exalbescens: (Fig. 61). Habitat: Quiet, often calcareous waters of ponds and lakes; commonly associated with Ceratophyllum demersum, Elodea canadensis, Lemna minor, Najas flexilis, Nuphar advena, Nymphaea odorata, Potamogeton foliosus, P. illinoensis, P. natans, P. pectinatus, P. zosteriformis, Ranunculus longirostris, and Vallisneria americana (Swink & Wilhelm 1994). Description: Leaves brittle, dark brown in color, entire specimens rare, often evidenced only by carbonized imprints in silt (Fig. 61), leaf segments usually less than 12 pairs. Stratigraphy: In fine organic sediments of lower strata at the Shafer Mastodont Locality. Chronology: The only dated record is 15,540 [+ or -] 70 ybp (Shafer Mastodont Locality). Frequency: 6%. Abundance: Frequent where found.

Order Ericales

Family Ericaceae

Andromeda glaucophylla: (Figs. 62, 63). Habitat: Most common in leatherleaf (Chamaedaphne calyculata) bogs, but may also occur in fens. Associates include Betula pumila, Chamaedaphne calyculata, Thelypteris palustris, Hypericum virginicum, Menyanthes trifoliata, Potentilla palustris, Sarracenia purpurea, Vaccinium macrocarpon, and V. oxycoccos. Description: Leaves (Figs. 62, 63) brown, linear, entire, revolute; surface glabrous, covered with black flecks, veins furrowed; undersides (Fig. 63) dull with raised midrib. Stratigraphy: Beginning at the transition from fen peat to Sphagnum peat and extending well into the Sphagnum peat. Chronology: The oldest dated record is 2835 ybp (Ropchan Memorial Bog). Frequency: 31%. Abundance: Infrequent to rare where found.

Chamaedaphne calyculata: (Fig. 64). Habitat: Mature Sphagnum bogs; usually associated with Vaccinium macrocarpon and/or Vaccinium oxycoccos. Description: Leaves (Fig. 64) poorly preserved, obovate, entire, covered with a thick cuticle bearing pits, pits absent where cuticle has deteriorated. Stratigraphy: Upper layers of Sphagnum peat. Chronology: The oldest record is 4010 [+ or -] 80 ybp (Burket Bog). Frequency: 19%. Abundance: Infrequent to rare where found.

Vaccinium macrocarpon: (Fig. 65). Habitat: Bogs and fens; often associated with Sphagnum, Chamaedaphne calyculata, and Sarracenia purpurea. Description: Leaves (Fig. 65) well preserved, oblong, thick, dark brown to black in color, midrib visible, other veins inconspicuous, margins of leaf slightly revolute. Stratigraphy: Upper reaches of brown moss (fen) peat and extending through the lower layers of Sphagnum peat. Chronology: The oldest dated record is 4110 [+ or -] 100 ybp (Dutch Street Bog). Frequency: 44%. Abundance: Frequent where found.

Order Gentianales

Family Gentianaceae

Menyanthes trifoliata: (Fig. 66). Habitat: Open, wet areas of neutral fens and mineral-rich Sphagnum bogs. Description: Achenes (Fig. 66) well preserved, shiny, dark brown to black in color, irregularly shaped, bearing concave depressions. Stratigraphy: Beginning in the uppermost portions of fen peats and extending into the early portions of Sphagnum peat. Chronology: The oldest dated record is 4010 [+ or -] 80 ybp (Burket Bog). Frequency: 31%. Abundance: Infrequent where found.

Order Campanulales

Family Asteraceae

Bidens sp.: (Fig. 67). Habitat: Wetlands. Description: Achenes (Fig. 67) poorly preserved, light brown in color, elongate-tapering, bearing four bristles. Stratigraphy: Fen peat in Little Chapman Bog. Chronology: The only dated record is ~ l850 [+ or -] 80 ybp (Little Chapman Bog). Frequency: 6%. Abundance: Extremely rare where found.

Kingdom Animalia

Phylum Mollusca

Class Gastropoda

Subclass Pulmonata

Order Basommatophora

Family Physidae

Physa sayii: (Fig. 68). Habitat: This species is common to still, shallow waters (0.3-0.8 m) in open areas. It prefers moderate vegetation and well-aerated water (Zimmerman l960). While Zimmerman (1960) reports that P. sayii prefers protected areas, Harmen & Berg (1971) found that it was most common in exposed areas. Goodrich & van der Schalie (1944) note that it can sometimes be found on wave battered shores. Description: Shell (Fig. 68) well-preserved when found but extremely fragile, sinistral, thin, globose, spire obtuseconical, body whorl extremely inflated (Harmen & Berg 1971); subfossils lacking periostracum. Chronology: The oldest dated record is 11,990 [+ or -] 90 ybp (Wilkinson Giant Beaver Locality). Stratigraphy: Found throughout the marl stratum in Kiser Lake Fen. In moderate to deep marls in the Wilkinson Giant Beaver Locality. Frequency: 13%. Abundance: Infrequent to rare where found.

Family Lymnaeidae

Lymnaea humilis: (Fig. 69). Habitat: Harmen & Berg (1971) report this species as inhabiting exposed mud flats, where they forage between the gravels with their shells partially exposed to the air. Goodrich & van der Schalie (1944) also report this species as inhabiting mud flats. Description: Shell (Fig. 69) well-preserved, up to 15 mm in length but more commonly less than 10 mm, dextral, relatively thick; spire acute-conical, bearing up to 7 whorls, sutures deeply impressed; growth lines inconspicuous, worn; aperture tear-shaped (Harmen & Berg 1971); subfossils lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 12,070 [+ or -] 50 ybp (Aker Mastodont Locality). Frequency: 25%. Abundance: Infrequent to frequent where found.

Lymnaea haldemani: (Fig. 70). Habitat: Common in shallow waters (0.3-1 m) of larger lakes in abundant vegetation. It prefers sheltered bays, and is commonly found on floating vegetation and on the undersides of water-lilies (Zimmerman 1960). It has also been found on rotting Typha leaves (Harmen & Berg 1971). This species is always found in limited numbers (Zimmerman 1960). It has not been recorded in Indiana in recent times. Description: Shell (Fig. 70) dextral, thin, up to 25 mm; spire extremely acute-conical, elongate; sutures impressed, up to 5 loosely coiled whorls, growth lines inconspicuous (Harmen & Berg 1971); subfossils extremely fragile, lack periostracum. Stratigraphy: Marl. Chronology: The youngest dated record is 11,240 [+ or -] 80 ybp (Wilkinson Giant Beaver Locality), and the oldest dated record is 12,070 [+ or -] 50 ybp (Aker Mastodont Locality). Frequency: 13%. Abundance: Extremely rare to rare where found.

Family Planorbidae

Helisoma anceps: (Figs. 71-73). Habitat: Common in shallow waters (<1 m) with abundant vegetation. While Reynolds (1959) reports that it prefers exposed habitats of open lakes, Harmen & Berg (1971) found it most commonly on inorganic substrates in protected areas of ponds as well as quiet pools of small streams. Description: Shell (Figs. 71-73) up to 15 mm, planospiral, about 3.5 loosely coiled whorls that are angulated above and below, spire deep, depressed on both sides; sutures shallow; growth lines conspicuous, crowded; aperture broadly lunate, sharply shouldered below and extending beyond plane of spire, inflated and rugose in mature specimens (Harmen & Berg 1971); subfossils well-preserved, but lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 12,070 ybp (Aker Mastodont Locality). Frequency: 19%. Abundance: Frequent to abundant where found.

Helisoma campanulata: (Figs. 74, 75). Habitat: Occurs in shallow waters of varying substrates in both protected and wave battered areas (Zimmerman 1960). Harmen & Berg (1971) found it mostly on inorganic substrates of small marshy lakes. They rarely found it associated with other Helisoma spp., with the exception of H. anceps and H. trivolvis. Dexter (1950) found the species to be common in Chara/Myriophyllum, Nymphaea/Pontedaria, and Decodon zones of a basic bog lake in Ohio. Description: Shell (Figs. 74, 75) up to 15 mm, sinistral, planospiral, with 4.5 tightly coiled whorls; sutures deep; growth lines conspicuous, evenly spaced, aperture broadly lunate, inflated on mature specimens (Harmen & Berg 1971); subfossils well-preserved, lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 12,070 ybp (Aker Mastodont Locality). Frequency: 19%. Abundance: Infrequent where found.

Gyraulus parvus: (Figs. 76, 77). Habitat: Occurs in small, shallow, protected waters (Zimmerman 1960), especially in ponds and backwaters with dense aquatic vegetation (Harmen & Berg 1971). Dexter (1950) found it to be restricted to the Potamogeton zone. Description: Shell (Figs. 76, 77) up to 7 mm, but mostly less than 4 mm, planospiral, 3.5 whorls; spire depressed; sutures deeply impressed; aperture broadly lunate, deflected downward (Harmen & Berg 1971); subfossils well-preserved, lack periostracum. Stratigraphy: Marl, rarely in limnic or hemic peat. Chronology: The oldest dated record is 12,590 [+ or -] 60 ybp (Aker Mastodont Locality). Frequency: 31%. Abundance: Extremely abundant to abundant where found.

Family Pleuroceridae

Pleurocera acuta: (Fig. 78). Habitat: Rivers and unprotected shores of lakes associated with rivers (Harmen & Berg 1971). Description: Shell (Fig. 78) dextral, up to 30 mm, thick, elongate and acute-conical, 7-14 whorls, apical whorls bearing 1-3 carinae; body whorl shouldered at outer periphery, striate below; aperture angulate, lacrimate, canaliculate (Harmen & Berg 1971); growth lines inconspicuous; subfossils usually fragmented, lack periostracum. Stratigraphy: Marl. Frequency: 6%. Abundance: Rare where found.

Family Hydrobiidae

Amnicola li,nosa: (Fig. 79). Habitat: Common in protected areas of shallow lakes and muddy bays in 0-3 m of water (Zimmerman 1960). It is also found in marshes, ponds, temporary stream pools, creeks and rivers (Harmen & Berg 1971). Reynolds (1959) reports that it has been found in brackish water as well as freshwater and prefers sandy substrates with dense beds of Chara, Potamogeton, Vallisneria, and Elodea. Dexter (1950) reports it from the Chara/Myriophyllwn, Nymphaca/Pontedaria, and Decodon zones. Zimmerman (1960) states the most important limiting factor for this species is vegetation (preferably abundant) and protection from exposure. He also reports that this species can endure long periods of emergence as long as it remains moist, but unusually high water temperatures can rapidly exterminate it from a waterbody. Description: Shell (Fig. 79) up to 5 mm, dextral; spire slightly elevated; apex truncated; sutures deep; whorls rounded, inflated, up to 4.5 in number; aperture broadly lacrimate (Harmen & Berg 1971); growth lines inconspicuous; subfossils well-preserved, lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 12,590 [+ or -] 60 ybp (Aker Mastodont Locality). Frequency: 19%. Abundance: Extremely abundant to abundant where found.

Amnicola lustrica: (Fig. 80). Habitat: This species is less common than A. limosa, although it occupies similar habitats (Harmen & Berg 1971). It prefers shallow (0-2 in), highly vegetated waters, where it often inhabits filamentous algae (Zimmerman 1960). Description: Shell (Fig. 80) dextral, elevated, acuteconical; sutures deep; aperture lacrimate (Harmen & Berg 1971); growth lines inconspicuous; subfossils well-preserved, lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 12,590 [+ or -] 60 ybp (Aker Mastodont Locality). Frequency: 25%. Abundance: Frequent to infrequent where found.

Family Valvatidae

Valvata tricarinata: (Figs. 81, 82). Habitat: Inhabits a wide variety of conditions but is most common in lakes. Harmen & Berg (1971) report that most specimens from lotic conditions are depauperate. Dexter (1950) found it to be common in the Chara/Myriophyllum, Potamogeton, Nymphaea/Pontedaria, and Decodon zones. Reynolds (1959) reports that the species is partial to firm bottoms and is usually associated with Oedogonium, Cladophora, and Vaucheria. Description: Shell (Figs. 81, 82) dextral, up to 5 mm, turreted; sutures deep; spire low; whorls 4, angulate, top, middle and bottom, each bearing a carina; aperture circular (Harmen & Berg 1971); growth lines somewhat conspicuous; subfossils well-preserved, lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 12,590 ybp (Aker Mastodont Locality). Frequency: 25%. Abundance: Extremely abundant where found.

Valvata sincera: (Figs. 83, 84). Habitat: This species is reported as being primarily from deep water (5-6 m), usually below 3 m in depth, of cold lakes with limited vegetation (Zimmerman 1960). Harmen & Berg (1971) found it at a depth of 5 m. Description: Shell (Figs. 83, 84) dextral, up to 4 mm, turreted; sutures deep; spire low; whorls 2.5, circular, acarinate; aperture circular (Harmen & Berg 1971); growth lines somewhat conspicuous to inconspicuous; subfossils well-preserved, lack periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 15,910 [+ or -] 90 ybp (Celery Bog). Frequency: 25%. Abundance: Infrequent to rare where found.

Order Ophistobranchia

Suborder Stylommatophora

Family Pupillidae

Gastrocopta sp.: (Fig. 85). Habitat: Terrestrial. Description: Shell (Fig. 85) ovate, smooth, aperture bearing large, blunt teeth; subfossil shells fragile. Stratigraphy: A few shells were found in the earliest sediments of the peat stratum of Kiser Lake Fen. Chronology: The oldest dated record is 4360 [+ or -] 100 ybp (Kiser Lake Fen). Frequency: 6%. Abundance: Infrequent to rare.

Family Zonitidae

Retinella sp.: (Figs. 86, 87). Habitat: Terrestrial. Description: Shell (Figs. 86, 87) thin, smooth, lustrous, depressed with four to six whorls, well-preserved. Stratigraphy: A few specimens in sandy marl of Kiser Lake Fen. Chronology: The oldest dated record is 4360 [+ or -] 100 ybp (Kiser Lake Fen). Frequency: 6%. Abundance: Rare.

Family Endodontidae

Helicodiscus parallelus: (Fig. 88). Habitat: Terrestrial. Goodrich & van der Schalie (1944) report this species as being most common to flood plains. Description: Shell (Fig. 88) disc-shaped, bearing parallel, raised, lines; spire flat; umbilicus broad, shallow. Stratigraphy: One specimen from the uppermost marl stratum of the Wilkinson Giant Beaver Locality, Whitley County, Indiana. Chronology: The oldest dated record is 11,240 + 80 ybp (Wilkinson Giant Beaver Locality). Frequency: 6%. Abundance: Extremely rare.

Class Bivalvia

Order Prionodesmacea

Family Unionidae

cf. Elliptio dilatata: (Fig. 89). Habitat: Lakes, ponds, and limnic waters with fish communities. Description: Valves (Fig. 89) very poorly preserved, powdery and brittle, periostracum present. Stratigraphy: Marl. Chronology: The oldest dated record is 11,240 [+ or -] 80 ybp (Wilkinson Giant Beaver Locality). Frequency: 6%. Abundance: Extremely rare.

Order Teleodesmacea

Family Sphaeriidae

Sphaerium sp.: (Fig. 90). Habitat: Lakes, ponds, marshes, swamps, sloughs, slow rivers and streams. Description: Valves (Fig. 90) up to 20 mm, nearly equal in morphology, symmetrical, nearly as long as broad, relatively thin; surface bearing eccentric ridges; subfossils moderately to poorly preserved, larger shells usually broken, surface often has remnants of periostracum. Stratigraphy: Marl. Chronology: The oldest dated record is 11,990 [+ or -] 90 ybp (Wilkinson Giant Beaver Locality). Frequency: 13%. Abundance: Abundant to frequent where found.

Pisidium sp.: (Fig. 91). Habitat: Lakes, ponds, marshes, swamps, sloughs, slow rivers and streams. Description: Valves (Fig. 91) up to 6 mm but usually 3-4 mm, laterally assymetrical; surface more or less smooth but eccentric growth rings visible; subfossils well-preserved, bearing remnants of the periostracum. Stratigraphy: Marl, rarely in limnic or sapric sediments. Chronology: The oldest dated record is 12,590 ybp (Aker Mastodont Locality). Frequency: 3%. Abutsdance: Extremely abundant to rare where found.

Phylum Arthropoda

Class Insecta

Order Coleoptera

Unidentified appendages: (Figs. 92-93). Habitat: Mostly terrestrial. Stratigraphy: Restricted mostly to peat strata. Frequency: 63%. Abundance: Abundant.

Order Trichoptera

Family Brachycentridae

cf. Micrasema sp.: (Fig. 94). Habitat: Weed-choked, lotic environments. Description: Case (Fig. 94) more or less cylindrical, open at both ends, constructed from Ceratophyllum demersumn stems. Stratigraphy: A single specimen from basal aquatic sediments of Svoboda Fen. Frequency: 6%. Abundance: Extremely rare.

Phylum Chordata

Class Osteichthyes

Family Centrarchidae

Lepomis cf. macrochirus: (Fig. 95). Habitat: All of the sunfish species prefer relatively warm waters generally found in mesotrophic to eutrophic waters of lakes and ponds; also found in lotic waters. The natural range of the family is from southern Canada to the Gulf of Mexico (Page & Burr 1991). Description: Scales (Fig. 95) ctenoid, subquadrate with 8-15 primary anterior radii that converge at the focus; radii crenate at scale margin; anterolateral corners square, postero-lateral corners rounded; focus located in posterior half of scale (Daniels 1996). Stratigraphy: Limnic sediments and marls of Kiser Lake Fen, Little Chapman Bog, and Little Arethusa Bog.

Chronology: The oldest dated record is >4360 ybp (Kiser Lake Fen). Frequency: 19%. Abundance. Infrequent where found. Appear sporadically throughout limnic sediments.

Family Percidae

Perca flavescens: (Fig. 96). Habitat: Freshwater lakes, ponds, and quiet areas of streams and rivers in the Atlantic, Arctic, Great Lakes, and Mississippi River Basins (Page & Burr 1991). Description: Scales (Fig. 96) ctenoid, with 4-8 primary radii in anterior field only; radii deeply cleft at scale margin; focus located on posterior third of scale (Daniels 1996). Stratigraphy: Limnic sediments of Celery Bog. Chronology: The oldest dated record is >9530 [+ or -] 90 ybp (Celery Bog). Frequency: 6%. Abundance: Somewhat frequent where found.

Class Reptilia 

Order Chelonia

Family Kinosternidae

Sternotherus odoratus: (Figs. 97-101). Habitat: Rivers, lakes, ponds, marshes, swamps, and sloughs. Prefers slow current and soft organic bottom or marl (J.A. Holman pers. comm.). Stratigraphy: Five bones (Figs. 97-101), presumably of a single animal, were found in the limnic sediment of Little Chapman Bog, Koscisuko County. Chronology: The only dated record is 3680 [+ or -] 80 ybp (Little Chapman Bog) (Swinehart & Holman 1999). Frequency: 6%. Abundance: Extremely rare.

CONCLUSIONS

Although not exhaustive, the present paper characterizes the macroscopic subfossil taxa common to wetland deposits in northern Indiana, and should provide useful information to other investigators working on the palaeoecology of wetlands in the southern Great Lakes region. Macrofossil surveys are a necessary complement to pollen data, especially when reconstructing local ecosystems. For example, although many pollen profiles show Picea as being abundant to within 8000 ybp, no macrofossils of Picea less than about 11,000 ybp have been recovered in Indiana. This suggests that macrofossil data may be more accurate for local or even regional reconstructions. Radiocarbon dating of macroscopic subfossils has indicated that many of the taxa which are common to temperate, eutrophic waters colonized aquatic environments as early as the late-Pleistocene, suggesting that conditions may have become favorable to these species earlier than previously thought.

Although the percent frequency determined for each taxon (based on 16 sites) is helpful, it is biased by the site selection methods. Most of the sites are peatland deposits that attracted the author because of their unique, boreal flora. Other sites were studied because of the discovery of ice-age mammal remains. Further investigations of different wetland types, such as emergent marshes and extant lakes, would add to the understanding of late-glacial and post-glacial biogeography. Additional radiocarbon dates will help further document the dates and rates of the colonization of various taxa after glacial retreat. Furthermore, use of scanning electron microscopy in the examination of small, obscure seeds is recommended. This will greatly increase the number of identifiable taxa.

[FIGURE 1 OMITTED]

Table 1

List of sites in Indiana where macroscopic subfossils were surveyed.

Site name                        Acronym  Location

Aker Mastodont Locality            AML    T33N, R1E, Sec. 3
Binkley Fen                        BIN    T38N, R13E, Sec. 31
Blueberry Bog                      BLB    T38N, R7E, Sec. 24
Bristol Fen                        BRF    T38N, R6E, Sec. 26
Burket Bog                         BUR    T32N, R5E, Sec. 20
Celery Bog                         CEL    T23N, R5W, Sec. 12
Dutch Street Bog                   DSB    T35N, R10E, Sec. 11
Kiser Lake Fen                     KLF    T33N, R7E, Sec. 13
Little Arethusa Bog                LAB    T31N, R7E, Sec. 7
Little Chapman Bog                 LCB    T33N, R6E, Sec. 35
Ropchan Memorial Bog               RMB    T38N, R12E, Sec. 22 & 23
Shafer Mastodont Locality          SML    T23N, R6W, Sec. 7
Svoboda Fen                        SVF    T35N, R11E, Sec. 8
Tamarack Bog                       TAM    T35N, R9E, Sec. 7
Wilkinson Giant Beaver Locality    WBL    T31N, R8E, Sec. 14
Yost Bog                           YB     T38N, R8E, Sec. 32

Site name                        County

Aker Mastodont Locality          Marshall
Binkley Fen                      Steuben
Blueberry Bog                    Elkhart
Bristol Fen                      Elkhart
Burket Bog                       Kosciusko
Celery Bog                       Tippecanoe
Dutch Street Bog                 Noble
Kiser Lake Fen                   Kosciusko
Little Arethusa Bog              Kosciusko
Little Chapman Bog               Kosciusko
Ropchan Memorial Bog             Steuben
Shafer Mastodont Locality        Warren
Svoboda Fen                      Noble
Tamarack Bog                     Noble
Wilkinson Giant Beaver Locality  Whitley
Yost Bog                         Lagrange

Table 2

The occurrence of subfossil taxa in 16 wetlands in northern Indiana. The
wetlands types are: (1) marsh, (2) marl fen, (3) fen, (4) tall-shrub
bog, (5) leatherleaf bog, and (6) forested peatland. The sites surveyed
(names abbreviated below) are: Shafer Mastodont Locality, Aker Mastodont
Locality, Wilkinson Giant Beaver Locality, Bristol Fen, Kiser Lake Fen,
Binkley Fen, Celery Bog, Svoboda Fen, Little Chapman Bog, Blueberry Bog,
Burket Bog, Dutch Street Bog, Yost Bog, Little Arethusa Bog, Ropchan
Memorial Bog, and Tamarack Bog.

                                         Wetlandtype
                           SML         AML      WBL      BRF
        Species            (1)         (2)      (2)      (2)

Algae

 Chara sp.                              X

Bryophytes

 Sphagnum spp.
 Meesia triquetra
 Thuidium delicatulum
 Campylium stellatum                             X
 Drepanocladus aduncus      X           X                 X
 Scorpidium scorpioides
 Calliergon stramineum
 Calliergon trifarium
 Polytrichum strictum

Conifers

 Picea glauca               X           X        X        X
 Picea mariana                          X                 X
 Picea sp.                  X
 Larix laricina             X           X        X
 Abies balsamea                                  X

Angiosperms

 Potamogeton spp.           X           X        X        X
 Najas flexilis             X           X        X        X
 Eleocharis sp.                         X
 Scirpus subterminalis
 Scirpus acutus-type                    X        X
 Carex cf. pseudocyperus
 Carex spp.                             X        X
 Dulichium arundinaceum
 Fuirena pumila
 Ceratophyllum demersum     X
 Nuphar advena                                   X        X
 Nymphaea odorata                                X
 Brasenia schreberi                              X
 Sarracenia purpurea
 Impatiens capensis
 Myriophyllum exalbescens   X
 Andromeda glaucophylla
 Chamaedaphne calyculata
 Vaccinium macrocarpon
 Menyanthes trifoliata
 Bidens sp.

Molluscs

 Physa sayii                                     X
 Lymnaea humilis                        X        X        X
 Lymnaea haldemani                               X        X
 Helisoma anceps                                 X        X
 Helisoma campanulata                            X        X
 Gyraulus parvus                        X        X        X
 Pleurocera acuta
 Amnicola limosa                                 X        X
 Amnicola lustrica                      X        X        X
 Valvata tricarinata                    X        X        X
 Valvata sincera                                 X        X
 Gastrocopta sp.
 Retinella sp.
 Helicodiscus parallelus                         X
 cf. Elliptio dilatata                           X
 Sphaerium sp.                                   X        X
 Pisidium sp.                           X        X        X

Insects

 Coleoptera
 cf. Micrasema sp.

Fishes

 Percidae
 Centrarchidae

Reptiles

 Sternotherus odoratus

                                         Wetlandtype
                           KLF       BIN       CEL       SVF
        Species            (2)       (3)       (3)       (3)

Algae

 Chara sp.                  X         X         X

Bryophytes

 Sphagnum spp.                                  X
 Meesia triquetra
 Thuidium delicatulum
 Campylium stellatum                  X
 Drepanocladus aduncus      X         X         X         X
 Scorpidium scorpioides                                   X
 Calliergon stramineum                X                   X
 Calliergon trifarium
 Polytrichum strictum

Conifers

 Picea glauca
 Picea mariana
 Picea sp.
 Larix laricina                       X         X
 Abies balsamea                                 X

Angiosperms

 Potamogeton spp.                     X         X
 Najas flexilis             X         X         X         X
 Eleocharis sp.                                 X
 Scirpus subterminalis
 Scirpus acutus-type        X         X         X
 Carex cf. pseudocyperus
 Carex spp.                 X                   X
 Dulichium arundinaceum
 Fuirena pumila
 Ceratophyllum demersum     X                   X         X
 Nuphar advena                                            X
 Nymphaea odorata
 Brasenia schreberi                   X         X
 Sarracenia purpurea
 Impatiens capensis                                       X
 Myriophyllum exalbescens
 Andromeda glaucophylla
 Chamaedaphne calyculata
 Vaccinium macrocarpon                X
 Menyanthes trifoliata
 Bidens sp.

Molluscs

 Physa sayii                X
 Lymnaea humilis            X
 Lymnaea haldemani
 Helisoma anceps            X
 Helisoma campanulata       X
 Gyraulus parvus            X
 Pleurocera acuta           X
 Amnicola limosa            X
 Amnicola lustrica          X
 Valvata tricarinata        X
 Valvata sincera            X                   X
 Gastrocopta sp.            X
 Retinella sp.              X
 Helicodiscus parallelus
 cf. Elliptio dilatata
 Sphaerium sp.
 Pisidium sp.               X

Insects

 Coleoptera                 X         X         X
 cf. Micrasema sp.                                        X

Fishes

 Percidae
 Centrarchidae              X

Reptiles

 Sternotherus odoratus

                                         Wetlandtype
                           LCB       BLB       BUR       DSB
        Species            (4)       (4)       (5)       (5)

Algae

 Chara sp.

Bryophytes

 Sphagnum spp.              X         X         X         X
 Meesia triquetra           X                             X
 Thuidium delicatulum
 Campylium stellatum
 Drepanocladus aduncus      X         X         X         X
 Scorpidium scorpioides
 Calliergon stramineum      X
 Calliergon trifarium       X         X         X         X
 Polytrichum strictum

Conifers

 Picea glauca
 Picea mariana
 Picea sp.                            X
 Larix laricina                       X
 Abies balsamea                       X

Angiosperms

 Potamogeton spp.                     X         X         X
 Najas flexilis             X         X         X         X
 Eleocharis sp.
 Scirpus subterminalis
 Scirpus acutus-type        X         X         X         X
 Carex cf. pseudocyperus              X
 Carex spp.                 X                   X
 Dulichium arundinaceum     X                   X
 Fuirena pumila
 Ceratophyllum demersum     X                   X         X
 Nuphar advena              X                   X         X
 Nymphaea odorata           X         X         X
 Brasenia schreberi         X         X         X         X
 Sarracenia purpurea                                      X
 Impatiens capensis
 Myriophyllum exalbescens
 Andromeda glaucophylla                         X
 Chamaedaphne calyculata                        X         X
 Vaccinium macrocarpon      X                   X         X
 Menyanthes trifoliata      X                   X         X
 Bidens sp.                 X

Molluscs

 Physa sayii
 Lymnaea humilis
 Lymnaea haldemani
 Helisoma anceps
 Helisoma campanulata
 Gyraulus parvus            X
 Pleurocera acuta
 Amnicola limosa
 Amnicola lustrica
 Valvata tricarinata
 Valvata sincera
 Gastrocopta sp.
 Retinella sp.
 Helicodiscus parallelus
 cf. Elliptio dilatata
 Sphaerium sp.
 Pisidium sp.

Insects

 Coleoptera                 X         X         X
 cf. Micrasema sp.

Fishes

 Percidae                   X
 Centrarchidae              X

Reptiles

 Sternotherus odoratus      X

                                         Wetlandtype
                           YB        LAB       RMB       TAM
        Species            (5)       (6)       (6)       (6)

Algae

 Chara sp.                  X                   X

Bryophytes

 Sphagnum spp.              X         X         X         X
 Meesia triquetra                     X         X         X
 Thuidium delicatulum                 X
 Campylium stellatum
 Drepanocladus aduncus      X         X
 Scorpidium scorpioides
 Calliergon stramineum                          X
 Calliergon trifarium                 X         X         X
 Polytrichum strictum       X

Conifers

 Picea glauca
 Picea mariana
 Picea sp.
 Larix laricina                       X         X         X
 Abies balsamea

Angiosperms

 Potamogeton spp.           X         X                   X
 Najas flexilis             X                   X         X
 Eleocharis sp.             X
 Scirpus subterminalis      X
 Scirpus acutus-type        X         X         X         X
 Carex cf. pseudocyperus
 Carex spp.                                     X         X
 Dulichium arundinaceum     X
 Fuirena pumila             X
 Ceratophyllum demersum               X
 Nuphar advena                        X         X
 Nymphaea odorata           X
 Brasenia schreberi         X         X
 Sarracenia purpurea
 Impatiens capensis
 Myriophyllum exalbescens
 Andromeda glaucophylla     X         X         X         X
 Chamaedaphne calyculata    X
 Vaccinium macrocarpon                X         X         X
 Menyanthes trifoliata      X                   X
 Bidens sp.

Molluscs

 Physa sayii
 Lymnaea humilis
 Lymnaea haldemani
 Helisoma anceps
 Helisoma campanulata
 Gyraulus parvus
 Pleurocera acuta
 Amnicola limosa
 Amnicola lustrica
 Valvata tricarinata
 Valvata sincera
 Gastrocopta sp.
 Retinella sp.
 Helicodiscus parallelus
 cf. Elliptio dilatata
 Sphaerium sp.
 Pisidium sp.               X         X

Insects

 Coleoptera                 X         X         X         X
 cf. Micrasema sp.

Fishes

 Percidae
 Centrarchidae                        X

Reptiles

 Sternotherus odoratus

                           Wetlandtype
                               %
        Species            Frequency

Algae

 Chara sp.                    38

Bryophytes

 Sphagnum spp.                56
 Meesia triquetra             31
 Thuidium delicatulum          6
 Campylium stellatum          13
 Drepanocladus aduncus        81
 Scorpidium scorpioides        6
 Calliergon stramineum        25
 Calliergon trifarium         44
 Polytrichum strictum          6

Conifers

 Picea glauca                 25
 Picea mariana                19
 Picea sp.                    13
 Larix laricina               56
 Abies balsamea               19

Angiosperms

 Potamogeton spp.             75
 Najas flexilis               94
 Eleocharis sp.               19
 Scirpus subterminalis         6
 Scirpus acutus-type          81
 Carex cf. pseudocyperus       6
 Carex spp.                   50
 Dulichium arundinaceum       13
 Fuirena pumila                6
 Ceratophyllum demersum       50
 Nuphar advena                50
 Nymphaea odorata             31
 Brasenia schreberi           56
 Sarracenia purpurea           6
 Impatiens capensis            6
 Myriophyllum exalbescens      6
 Andromeda glaucophylla       31
 Chamaedaphne calyculata      19
 Vaccinium macrocarpon        44
 Menyanthes trifoliata        31
 Bidens sp.                    6

Molluscs

 Physa sayii                  13
 Lymnaea humilis              25
 Lymnaea haldemani            13
 Helisoma anceps              19
 Helisoma campanulata         19
 Gyraulus parvus              31
 Pleurocera acuta              6
 Amnicola limosa              19
 Amnicola lustrica            25
 Valvata tricarinata          25
 Valvata sincera              25
 Gastrocopta sp.               6
 Retinella sp.                 6
 Helicodiscus parallelus       6
 cf. Elliptio dilatata         6
 Sphaerium sp.                13
 Pisidium sp.                 38

Insects

 Coleoptera                   63
 cf. Micrasema sp.             6

Fishes

 Percidae                      6
 Centrarchidae                19

Reptiles

 Sternotherus odoratus         6

ACKNOWLEDGMENTS

The author would like to thank Drs. Jonathan N. Roth and Larry R. Yoder of Goshen College, Drs. Gilbert D. Starks and Daniel E. Wujek of Central Michigan University, Dr. George R. Parker of Purdue University, and Mr. Ronald L. Richards and the staff of the Indiana State Museum for providing assistance throughout the study. Dr. Paul Colinvaux of Ohio State University, Dr. Norton Miller of the New York State Museum, and Dr. Howard Crum of the University of Michigan also provided suggestions during the data collection. Gina Warner, Melody Myers-Kinzie, and Justin Mandrelle provided assistance in the field and laboratory. Special thanks is extended to the Basil S. Turner Foundation, the West Lafayette Parks and Recreation Department, and the Indiana Academy of Science for providing funding for various portions of the research since 1991.

LITERATURE CITED

Crum, H.A. & L.E. Anderson. 1981. Mosses of Eastern North America. Columbia University Press, New York. 2 vol. 1328 pp.

Daniels, R.A. 1996. Guide to the identification of scales of inland fishes of northeastern North America. New York State Museum Bulletin, No. 488. 97 pp.

Dexter, R.W. 1950. Distribution of the mollusks in a basic bog lake and its margins. The Nautilus 64:19-26.

Friesner, R.C. & J.E. Potzger. 1946. The Cabin Creek Raised Bog, Randolph County, Indiana. Butler University Botanical Studies 8:24-43.

Goodrich, C. & H. van der Schalie. 1944. A revision of the Mollusca of Indiana. American Midland Naturalist 32:257-326.

Harmen, W.N. & C.O. Berg. 1971. The freshwater snails of central New York. SEARCH-Agriculture (Cornell University) 1:1-68.

Hunt, L.L. & R.L. Richards. 1992. The Lewis Mastodont (Mammut americanum) locality, Wabash County, north-central Indiana. Proceedings of the Indiana Academy of Science 101:221-227.

Jackson, S.T., D.R. Whitehead & G.D. Ellis. 1986. Late-glacial and early Holocene vegetational history at the Kolarik Mastodon site, northwestern Indiana. American Midland Naturalist 115:361-373.

Janssens, J.A. 1983. Past and present distribution of Drepanocladus in North America, with notes on the differentiation of fossil fragments. Journal of the Hattori Botanical Laboratory 54:251-298.

Jessen, K. 1955. Key to subfossil Potamogeton. Botanisk Tidsskrift 52:1-7.

Montgomery F.H. 1977. Seeds and Fruits of Plants of Eastern Canada and Northeastern United States. University of Toronto Press, Toronto. 212 pp.

Page, L.M. & B.M. Burr. 1991. A Field Guide to Freshwater Fishes. Houghton-Mifflin Co., Boston. 432 pp.

Potzger, J.E. 1936. Post-Pleistocene fossil records in peat of the upper Blue River valley, Henry County, Indiana. Proceedings of the Indiana Academy of Science 45:65-68.

Reynolds, M.B. 1959. Pleistocene molluscan faunas of the Humboldt deposit, Ross County, Ohio. Ohio Journal of Science 59:152-166.

Richards, R.L., D.R. Whitehead & D.R. Cochran. 1987. The Dollens mastodon (Mammut americanum) locality, Madison County, east-central Indiana. Proceedings of the Indiana Academy of Science 97:571-581.

Swinehart, A.L. 1995a. Palaeoecology of an alkaline peatland in Elkhart County, Indiana. Proceedings of the Indiana Academy of Science 104:43-46.

Swinehart, A.L. 1995b. Subfossils of the boreal mosses Calliergon trifarium and Meesia triquetra in an Indiana peatland. Ohio Journal of Science 95:278-280.

Swinehart, A.L. 1996. Palaeoenvironmental reconstruction of the Shafer mastodont locality, Warren County, Indiana. Report to the Indiana Department of Natural Resources, Indiana State Museum. 14 pp.

Swinehart, A.L. 1997. The development and ecology of peatlands in Indiana. Ph.D. Dissertation, Department of Forestry & Natural Resources, Purdue University, West Lafayette, Indiana. 303 pp.

Swinehart, A.L. & J.A. Holman. 1999. Subfossils of the common musk turtle (Sternotherus odoratus) from a Holocene peat deposit in northern Indiana. American Midland Naturalist 142:191-193.

Swinehart, A.L. & G.R. Parker. 2000. Palaeoecology and development of peatlands in Indiana. American Midland Naturalist 143:267-297.

Swinehart, A.L. & R.L. Richards. 2001. Palaeoecology of a northeast Indiana wetland harboring remains of the Pleistocene giant beaver (Castoroides ohioensis). Proceedings of the Indiana Academy of Science 110:151-166.

Swinehart, A.L. & G.D. Starks. 1994. A record of the natural history and anthropogenic senescence of an Indiana tamarack bog. Proceedings of the Indiana Academy of Science 103:225-239.

Swink, F. & G. Wilhelm. 1994. Plants of the Chicago Region. 4th ed. Indiana Academy of Science, Indianapolis. 921 pp.

Voss, E.G. 1972. Michigan Flora, Vol. 2. Cranbrook Institute of Science, Bloomfield Hills, Michigan. 724 pp.

Welch, W.H. 1957, Mosses of Indiana. Indiana Department of Conservation, Indianapolis. 478 pp.

Whitehead, D.R., S.T. Jackson, M.C. Sheenan & B.W. Leyden. 1982. Late-glacial vegetation associated with caribou and mastodon in central Indiana. Quaternary Research 17:241-257.

Zimmerman, J.A. 1960. Pleistocene molluscan faunas of the Newell Lake Deposit, Logan County, Ohio. Ohio Journal of Science 60:13-39.

Manuscript received 26 March 2002, revised 15 August 2002.