Palaeoecology of a Northeast Indiana Wetland harboring remains of the pleistocene giant beaver (Castoroides ohioenis).ABSTRACT. Recovery of a femur femur (fē`mər): see leg. of an adult Pleistocene giant beaver The Giant Beaver (Castoroides ohioensis) was a huge species of rodent, with a length up to 2.5 m (8.2 feet)[0] and an estimated weight of 60-100 kg (130-220 lbs), although some estimates have ranged as high as 220 kg (485 lbs). (Castoroides ohioensis) from a cornfield in Whitley County, Indiana Whitley County is a county located in the U.S. state of Indiana. As of 2000, the population was 30,707. The county seat is Columbia City6. Geography According to the U.S. Census Bureau, the county has a total area of 875 km² (338 mi²). , prompted an analysis of the palaeoecology paleoecology, palaeoecology the branch of ecology that studies the relationship of ancient plants and animals to their environments. — paleoecologic, palaeoecologic, paleoecological, palaeoecological, adj. of the site. Inspection of historic maps and more recent United States Geological Survey The United States Geological Survey (USGS) is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. (USGS USGS United States Geological Survey (US Department of the Interior) ) topographic maps facilitated reconstruction of the pre-disturbance physiography of the site. What is currently a ditched agricultural area was once an extensive shallow lake associated with Spring Creek A spring creek is a stream that flows from a spring. Spring Creek may refer to any of the following specific places:
adj. Relating to, characterized by, or promoting eutrophia. , mineral-rich, and surrounded by boreal forest boreal forest Noun the forest of northern latitudes, esp. in Scandinavia, Canada, and Siberia, consisting mainly of spruce and pine [Latin boreas the north wind] for much of its existence. A radiocarbon ra·di·o·car·bon n. A radioactive isotope of carbon, especially carbon 14. radiocarbon Noun a radioactive isotope of carbon, esp. date of 11,240 [+ or -] 80 yr BP taken within 10 cm of the upper limit of limnogenic sediments, suggests that the lake was extinguished at an early time, perhaps before the d emise of the boreal forest. The lake was succeeded by an emergent marsh and finally a peat-forming wetland dominated by bulrushes (Scirpus spp.). Anthropogenic an·thro·po·gen·ic adj. 1. Of or relating to anthropogenesis. 2. Caused by humans: anthropogenic degradation of the environment. re-routing of Spring Creek and other ditching has desiccated des·ic·cate v. des·ic·cat·ed, des·ic·cat·ing, des·ic·cates v.tr. 1. To dry out thoroughly. 2. To preserve (foods) by removing the moisture. See Synonyms at dry. 3. the wetland, and only farmland remains. Thirteen plant species and 16 animal species (mostly mollusks) were recovered from the site. The gastropod gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. assemblage was similar to other late-glacial and Holocene marls with only a few exceptions. One species recorded in the deposit, Lyrnnaea haldemanni, is no longer extant in Indiana. Helicodiscus parellelus and Uniomerus tetralasmus are reported as new subfossil sub·fos·sil adj. Partly fossilized: subfossil animals and plants. n. A subfossil organism. records for the region. The giant beaver remains are presumed to have been deposited circa 10,000 yr BP, the same time that the species is thought to have gone extinct. Keywords: Castoroides, Gastropoda, Indiana, lakes, macrofossil mac·ro·fos·sil n. A fossil large enough to be examined without a microscope. , palcoecology, peatland, Pleistocene The giant beaver, the largest rodent of the North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. Pleistocene, is surrounded by controversy. Much of this controversy involves whether or not the Pleistocene giant beaver (Castoroides ohicensis) shared feeding and behavioral characteristics with the modern beaver (Castor). Castoroides ohicensis attained lengths of 1.9-2.2 m (6.2-7.2 feet) and weights of 90-125 kg (200-275 lbs) (McDonald 1994). Early studies concluded that the giant beaver felled trees and built dams as does the modern beaver (e.g., Moore 1890; Hay 1912; Cahn 1932). Moreover, the medial "pinching" of the internal pterygoid plate of the skull, which constricts the posterior end of the nasal passage into upper and lower vents (Moore 1890; Hay 1912; Stirton 1965), was thought by Stirton (1965) to offer a greater air reserve for the extended underwater activity that is so common in Castor. Later studies suggest that the incisors were not efficient in cutting trees, and that the giant beaver did not, therefore, construct dams (Powell 1948; Stirton 1965; Holman 1975, 1995; Kurten & Anderson 1980; McDonald 1994). Furthermore, Hay (1912) had long before noted that the "pinching" of the internal plerygoid plate and other alterations of the skull had been an accommodation for the insertion of large internal pterygoid muscles into the pterygoid pterygoid /pter·y·goid/ (ter´i-goid) shaped like a wing. pter·y·goid adj. 1. Of, relating to, or located in the region of the sphenoid bone. 2. fossae, rather than a cavity for air reserves. Finally, Holman (1975, 1995) related that Castoroides had a smaller brain with a smoother outer surface than in Castor, suggesting that Castoroides had much less complex behavior patterns and social interactions than the latter. There is a general agreement that Castoroides thrived in lakes and ponds that were bordered by swamps (Powell 1948; Stirton 1965; Saunders 1977; Kurten & Anderson 1980; Harington 1986; Holman 1995) as well as marsh habitats (Holman 1975, 1995). The giant beaver is thought to have co-existed alongside the American mastodont, Mammut americanum (Moore 1890; Powell 1948; Graham et al. 1983) and the modern beaver (Harington 1986; McDonald 1994). Most authors believe that Castoroides was a good swimmer, though was clumsy on land. Its habits have been envisioned more as those of the marsh-dwelling muskrat muskrat, North American aquatic rodent. The common muskrats, species of the genus Ondatra, are sometimes called by their Native American name, musquash. (Stirton 1965; Kurten & Anderson 1980), as a giant "swamp rat" moving along wide trails through the coarse vegetation of the marshy marsh·y adj. marsh·i·er, marsh·i·est 1. Of, resembling, or characterized by a marsh or marshes; boggy. 2. Growing in marshes. shores of a lake or across the swampy floodplain floodplain, level land along the course of a river formed by the deposition of sediment during periodic floods. Floodplains contain such features as levees, backswamps, delta plains, and oxbow lakes. of a glacial river (Powell 1948), or as a "large, clumsy water hog," meandering about in marshes and ponds feeding upon aquatic vegetation (Holman 1975, 1995). It is thought to have fed upon coarse leaves, the roots of sedges, cattails, and other vegetation (Powell 1948; McDonald 1994). Many authors believe that a reduction or loss of its preferred habitat at the end of the Pleistocene and perhaps its overspecialization, including the inability to disperse readily and to build dams, contributed to its extinction (Stirton 1965; Kurten & Anderson 1980; Harington 1986; Holman 1995). Direct competition with the modern beaver may also have been involved (Powell 1948; Kurten & Anderson 1980; Holman 1995). Although Castoroides remains are relatively frequent in Indiana, few of those remains have been recovered in a context that allowed detailed interpretation of the rodent's habitat. With the controversy regarding the animals' behavior, adaptations, and sudden extinction, the examination of the plant and animal sub-fossils found in association with the giant beaver becomes important. Additionally, the palaeoecology of marl Marl, city, Germany Marl (märl), city (1994 pop. 92,590), North Rhine–Westphalia, W Germany. It is an industrial and mining (coal, lead, and zinc) center, and also supports a number of chemical factories. deposits, such as the Wilkinson Locality (described herein), in general, has received less scientific attention than peat deposits. Although several studies have been conducted on marl deposits in North America (Baker 1918; Baker 1920; Whittaker 1921; Russell 1934; La Rocque 1952; Reynolds 1959; Zimmerman 1960; Swinehart 1995), the study of macroscopic macroscopic /mac·ro·scop·ic/ (mak?ro-skop´ik) gross (2). mac·ro·scop·ic or mac·ro·scop·i·cal adj. 1. Large enough to be perceived or examined by the unaided eye. 2. subfossils in Indiana's marl deposits has been almost entirely neglected. Only a few studies have been conducted. (Baker 1920; Swinehart 1995; Swinehart & Parker 2000; and a note in Blatchley & Ashley's (1901) treatise on the lakes and marl de posits of the northern part of the State). The present paper reports on macroscopic subfossils recovered from the Wilkinson Giant Beaver Locality in northeast Indiana. The objectives are to: 1) reconstruct the palaeoenvironment of the Wilkinson giant beaver using macroscopic subfossils as indicators, 2) document, using subfossils and stratigraphy stratigraphy, branch of geology specifically concerned with the arrangement of layered rocks (see stratification). Stratigraphy is based on the law of superposition, which states that in a normal sequence of rock layers the youngest is on top and the oldest on the , the biological and limnological lim·nol·o·gy n. The scientific study of the life and phenomena of fresh water, especially lakes and ponds. [Greek limn changes of the wetland from time of creation to present, 3) compare the subfossils of the Wilkinson Site to other post-glacial wetland deposits in the southern Great Lakes region The Great Lakes region can refer to:
STUDY AREA The Wilkinson Locality is located 2.7 miles SE of Larwill, Whitley County, Indiana (NWQ, SWQ SWQ Swieqi (postal locality, Malta) SWQ Sumbawa Island, Indonesia - Brang Bidji (Airport Code) , SWQ, NEQ NEQ Numéro d'Entreprise du Québec (French: Québec Enterprise Number) NEQ Net Explosive Quantity NEQ New England Quarterly NEQ Noise Equivalent Quanta NEQ Northeast Qualifier (gaming tournament) , Sec. 14, T31N, R8E, Lorane Quad). The area is situated in an outwash outwash Deposit of sand and gravel carried by running water from the melting ice of a glacier and laid down in stratified deposits. An outwash may be as much as 330 ft (100 m) thick at the edge of a glacier, and it may extend for many miles. channel associated with the interlobate Packerton Moraine of late-Wisconsin age. The outwash channel is filled with marls, mucks, and peats (Gray 1989); and these deposits are traversed by Spring Creek, which flows into the Eel River. The bedrock under-neath the drift is composed of dolomite dolomite (dō`ləmīt', dŏl`ə–). 1 Mineral, calcium magnesium carbonate, CaMg (CO3)2. and limestone (Gray 1987), and the glacial drift is also limestone-rich. These qualities impart alkaline waters throughout the region except for a few rare cases where biological and other processes favor acidification acidification a technology used by processors to preserve foods by adding acids (such as acetic, citric, phosphoric, propionic and lactic acid) and thereby reduce the risk of growth of harmful bacteria. . The study site is dominated by limnic and wetland sediments created by an extinct, shallow lake associated with Spring Creek. The original course of Spring Creek was changed as early as the late 1800's by extensive ditching. Subsequent farming has resulted in an area that bears little resemblance to its aquatic origins. Figure 1 illustrates, based on historic maps, soil surveys, and local topography, what the site might have looked like during pre-settlement times. METHODS Field methods.--Three exploratory trenches were dug near the site of the recovery of a Castoroides femur discovered by Monte Wilkinsen, owner of the site. This was done initially by backhoe, then with shovel, and finally by trowel as the peat-marl interface (the level where the bone was recovered) was reached. Because no additional elements of the giant beaver were located during initial trenching, the trenches were then extended further outward, by backhoe, from the original spot of the find (Fig. 2). Water seepage was periodically pumped out of the trenches with a gasoline-powered pump. Initially, randomly selected bulk samples of sediment were washed through a 1.2 mm mesh screen for recovery of vertebrate, mollusk mollusk: see Mollusca. mollusk or mollusc Any of some 75,000 species of soft-bodied invertebrate animals (phylum Mollusca), many of which are wholly or partly enclosed in a calcium carbonate shell secreted by the mantle, a soft , and plant macrofossil materials. However, only plant macrofossils and mollusks, and no vertebrates, were recovered by this sampling, suggesting the Castoroides femur was a solitary bone not associated with the remainder of the skeleton. Therefore, a more systematic method was implemented to foc us on the palaeonvironment (plant and invertebrate invertebrate (ĭn'vûr`təbrət, –brāt'), any animal lacking a backbone. The invertebrates include the tunicates and lancelets of phylum Chordata, as well as all animal phyla other than Chordata. subfossils) of the site. A one square-meter column of sediment was removed by trowel at 10 cm intervals from the surface down to the base of the deposit. The sediments were then transported to screening stations for washing, and the resulting concentrate was bagged for laboratory re-washing, sorting, and analysis. Water for screening was provided by pumps, drawing from groundwater seepage from a nearby sump. Additionally, bulk sediments were taken from each 10 cm depth interval and bagged for more detailed, quantitative sampling to be conducted in the laboratory. Laboratory methods.--In the laboratory, all concentrate was re-washed to remove additional sand and clay. The resulting concentrate was dried and examined under a binocular microscope binocular microscope n. A microscope having two eyepieces, one for each eye, so that the object can be viewed with both eyes. (10X), and the subfossils were hand sorted. Wood samples from the 70-80 and 90-100 cm depth intervals were submitted to Beta Analytic, Inc., for radiocarbon ((14)C) dating. Swinehart undertook the study of plant macrofossils, mollusks, and the sediment samples, and Richards studied the few vertebrate remains. Coarse, medium, and fine gravels, as well as woody and fibrous material from each depth interval were separated, oven-dried, and weighed with a Mettler PE 360 balance. Organic subfossil remains from the bulk-screening residues from all depths were identified and counted. This analysis was supplemental to that conducted on the bulk samples, and resulted in the documentation of infrequent macrofossils not encountered in the sub-sampling of bulk material. Bulk sediment was sub-sampled in the laboratory for macrofossil analysis. Subsamples of 50 [cm.sup.3] volumes from each 10 cm depth interval were obtained by water displacement. Macrofossil subsamples were dispersed by gentle agitation in warm water. Some clasts of sediment required breakage by hand underwater. Dispersed sediments were then washed through a series of sieves, the smallest being 0.4 mm mesh. Sieve residue was placed into containers and analyzed immediately. All recognizable macrofossils were identified and counted. The resulting macrofossil diagrams represent the number of fragments per 50 [cm.sup.3] of bulk sediment (Fig. 2). Seeds and achenes were identified with the aid of Montgomery (1977), Martin & Barkely (1961), and Jessen (1955); mosses, Crum & Anderson (1981); bivalves, Cummings & Mayer (1992); and gastropods, Harmen & Berg (1971). Macrofossil diagrams were generated using Tilia[C] and Tilia*Graph[C] computer software (Grimm 1996). Voucher specimens of macrofossils were placed in vial s containing 60% ethanol and are held by the first author and by the Indiana State Museum. RESULTS Age and stratigraphy.--The depth of limnic and wetland sediments at the Wilkinson Locality was 170 cm. The underlying material was composed of glacial outwash that was superseded by a layer of silt (10 cm). Most of the profile was composed of marl. The 70-80 cm and 90-100 cm depths had radiocarbon dates of 11,240 [+ or -] 80 yr BP and 11,990 [+ or -] 90 yr BP, respectively. The marl layer was probably produced between 14,000 and 10,500 yr BR It is superseded by 20 cm of hemic hemic /he·mic/ (he´mik) (hem´ik) pertaining to blood. he·mic adj. Of or relating to the blood. hemic pertaining to blood. sedge sedge, common name for members of the Cyperaceae, a family of grasslike and rushlike herbs found in all parts of the world, especially in marshes of subarctic and temperate zones. peat, sand and humus humus (hy  `məs), organic matter that has decayed to a relatively stable, amorphous state. It is an important biological constituent of fertile soil. . The amount of coarse gravel (> 4 mm diameter) remained
relatively constant throughout the profile but increased dramatically
near the top of the marl stratum before disappearing at the initiation
of the peat layer (Fig. 2). Smaller gravels and sands were present
throughout the profile.
Systematic palaeobiology paleobiology, palaeobiology the branch of paleontology that studies fossil plants and animals. — paleobiologist, palaeobiologist, n. — paleobiologic, palaeobiologic, paleobiological, palaeobiological, adj. .--Thirteen plant taxa taxa: see taxon. and sixteen animal taxa were recovered as macroscopic subfossils (Fig. 2). A brief discussion of each is presented below. KINGDOM PLANTAE Division Bryophyta Family Amblystegiaceae cf. Campylium stellatum (Hedw.) C. Jens.--Subfossil Material: Gametophyte gametophyte (gəmē`təfīt'), phase of plant life cycles in which the gametes, i.e., egg and sperm, are produced. The gametophyte is haploid, that is, each cell contains a single complete set of chromosomes, and arises from the fragments (INSM INSM Initiative Neue Soziale Marktwirtschaft (German) INSM Integrated Network and Systems Management 71.12.2901 .001-.002; Swinehart #4B.4.3.16). Occurrence: Occasional in marl between the depths of 120-140 cm. Habitat: In open, wet areas of highly alkaline marshes and fens (Crum & Anderson 1980). Also found in swamps and on wet banks (Welch 1957). Division Spermatophyta Family Pinaceae Abies balsamea (L.) Mill.--Subfossil material: Leaf fragments (INSM 71.12.002901. 003). Occurrence: Infrequent in marl, silt, and outwash between the depths of 100-165 cm. Habitat: Coniferous con·i·fer n. Any of various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing gymnospermous trees or shrubs such as pines, spruces, and firs. and mixed forests; occasionally in cedar swamps, fens, and bogs. Comments: Other macroscopic subfossil records from Indiana include Blueberry blueberry, plant of the large genus Vaccinium, widely distributed shrubs (occasionally small trees) of the family Ericaceae (heath family), usually found on acid soil. They are often confused with the related huckleberry. Bog, Elkhart County (Swinehart & Parker 2000) and Celery Bog, Tippecanoe County (Swinehart unpubl. data). Larix laricina (DuRoi) K. Koch.--Subfossil material: Leaf scarred portions of twigs (INSM 71.12.002901.004-.005). Occurrence: Occasional in marl and silt between the depths of 100-150 cm. 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. Comments: Other macroscopic subfossil records from Indiana include Prairie Creek Site, Daviess County (Whitehead & Jackson n.d.); Blueberry Bog, Elkhart County (Swinehart & Parker 2000); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Little Arethusa Arethusa, in Greek mythology Arethusa (ărĭth `sə), in Greek mythology, nymph favored by Artemis and loved by the river god Alpheus. Bog, Kosciusko County (Swinehart & Parker 2000);
Binkley Pen and Ropchan Memorial Bog, Steuben County (Swinehart &
Parker 2000); Celery Bog, Tippecanoe County (Swinehart unpubl.); Shafer
Mastodont Site, Warren County (Swinehart 1996).
Picea glauca (Moensch) Voss.-Subfossil material: Leaves and cones (INSM 71.12. 002901.006; Swinehart #4B .4.14.15). Occurrence: Frequent in marl and silt between the depths of 80-150 cm. Also present in outwash at a depth of 165 cm. Habitat: Well-drained coniferous swamps, lakeshores and stream-borders, mixed forests (Voss 1972), and occasionally in peatlands; mostly in boreal bo·re·al adj. 1. Of or relating to the north; northern. 2. Of or concerning the north wind. 3. Boreal climates. Extinct in Indiana. Comments: Other macroscopic subfossil records from Indiana include Prairie Creek Site, Daviess County (Whitehead & Jackson, n.d.); Bristol Pen, Elkhart County (Swinehart 1995); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Shafer Mastodont Site, Warren County (Swinehart 1996); Aker Mastodont Site, Marshall County (Swinehart unpubl. data). Family Potamogetonaceae Potamogeton praelongus Wulfen.--Subfossil material: Achenes (INSM 71.12.002901. 008-.011). Occurrence: Common in marl between the depths of 60-100 cm. 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). Potamogeton pusillus L.--Subfossil material: Achenes (INSM 71.12.002901.035). Occurrence: Infrequent in marl and silt between the depths of 90-150 cm. Habitat: Lakes and ponds and occasionally quiet waters of streams, in shallow waters less than 2 m (Voss 1972), prefers calcareous calcareous /cal·car·e·ous/ (kal-kar´e-us) pertaining to or containing lime; chalky. cal·car·e·ous adj. waters, often associated with Elodea canadensis, Myriophyllum exalbescens, Najas fiexilis, Nuphar advena, Potamogeton natans, P. nodosus, P. pectinatus, P. zosteriformis, and Vallisneria americana (Swink & Wilhelm 1994). Comments: Other macroscopic subfossil records of the genus Potamogeton from Indiana include Prairie Creek Site, Daviess County (Whitehead & Jackson, n.d.); Blueberry Bog and Bristol Fen, Elkhart County (Swinehart 1995; Swinehart & Parker 2000); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Burket Bog and Little Arethusa Bog, Kosciusko County (Swinehart & Parker 2000); Yost Bog, Lagrange County (Swinehart & Parker 2000); Aker Mastodont Site, Marshall County (Swinehart unpubl. data); Dutch Street Bog, Noble County (Swinehart & Parker 2000); Binkley Fen, Steuben County (Swinehart & Parker 2000); Shafer Mastodont Site, Warren County (Swinehart 1996). Family Najadaceae Najas flexilis (Willd.) Rostk. & F.W. Schmidt.--Subfossil material: Achenes (INSM 71.12.002901.012; Swinehart #4B.4. 16.18). Occurrence: Extremely abundant in marl throughout the 60-130 cm depths. Habitat: Extremely common in lakes, ponds, marshes, sloughs, rivers and streams. Also found on soft bottoms of open waters in peat-lands. 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. Comments: Other macroscopic subfossil records of Najas flexilis from Indiana include Blueberry Bog and Bristol Pen in Elkhart County (Swinehart 1995; Swinehart & Parker 2000); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Burket Bog, Little Chapman Bog, and Kaiser Lake Pen in Kosciusko County (Swinehart & Parker 2000); Yost Bog, Lagrange County (Swinehart & Parker 2000); Aker Mastodont Site, Marshall County (Swinehart unpubl. ); Dutch Street Bog, Tamarack tamarack: see larch. Bog, and Svoboda Fen in Noble County (Swinehart 1994; Swinehart & Parker 2000); Binkley Fen and Ropchan Memorial Bog in Steuben County (Swinehart & Parker 2000); and the Shafer Mastodont Site, Warren County (Swinehart 1996). Family Cyperaceae Carex sp.--Subfossil material: Achenes (INSM 71.12.002901.0l5). Occurrence: Infrequent in marl and silt in the 90-150 cm depths. Habitat: Variable. Comments: Other macroscopic subfossil records of Carex from Indiana include Prairie Creek Site, Daviess County (Whitehead & Jackson, n.d.); Blueberry Bog, Elkhart County (Swinehart & Parker 2000); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Burket Bog, Little Chapman Bog, and Kiser Lake Fen in Kosciusko County (Swinehart & Parker 2000); and Ropchan Memorial Bog, Steuben County (Swinehart & Parker 2000). Scirpus acutus (Muhl.).--Subfossil material: Achenes (INSM 71.12.002901.016; Swinehart #4B.4.16.19). Occurrence: Extremely abundant in marl and sedge peat between the depths of 40-110 cm. Habitat: In shallow water or wet areas around lakes, ponds, marshes, and flowing waters; also found in fens and marl flats. Scirpus validus which has a similar achene achene (əkēn`), dry, simple, one-seeded fruit with the seed attached to the inner wall at only one point. Achenes are indehiscent, i.e., they do not split open at maturity. grows in similar habitats. Comments: Other macroscopic subfossil records of Scirpus from Indiana include Blueberry Bog, Elkhart County (Swinehart & Parker 2000); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Burket Bog, Little Arethusa Bog, Little Chapman Bog, and Kiser Lake Fen in Kosciusko County (Swinehart & Parker 2000); Yost Bog, Lagrange County (Swinehart & Parker 2000); Aker Mastodont Site, Marshall County (Swinehart, unpubl. data); Dutch Street Bog, Noble County (Swinehart & Parker 2000); and Binkley Fen and Ropchan Memorial Bog in Steuben County (Swinehart & Parker 2000). Family Nymphaeaceae Brasenia schreberi Gmel.--Subfossil material: Seeds (INSM 71.12.002901.020-.021). Occurrence: Frequent in marl between the 80-100 cm depths. Habitat: Quiet ponds and lakes, usually in soft, acid waters acid waters waters with a low pH occurring naturally and where water contaminated by acid rain and run-off from mine sites; acid waters often contain higher concentrations than normal of cadmium, copper, zinc and lead. (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). Comments: Other macroscopic subfossil records of Brasenia schreberi from Indiana include Blueberry Bog, Elkhart County (Swinehart & Parker 2000); Yost Bog, Lagrange County (Swinehart & Parker 2000); Burket Bog, Little Arethusa Bog, and Little Chapman Bog in Kosciusko County (Swinehart & Parker 2000); Dutch Street Bog and Tamarack Bog in Noble County (Swinehart 1994; Swinehart & Parker 2000); and Binkley Fen, Steuben County (Swinehart & Parker 2000). Nymphaea tuberosa Paine.--Subfossil material: Seeds (INSM 71.12.002901.022-.024). Occurrence: Infrequent in marl between the 80-120 cm depths. Habitat: Emergent in quiet, shallow water of lakes, ponds, rivers and streams. Often associated with Brasenia schreberi, Ceratophyllum demersum, Lemna minor, Nalas flexilis, Nuphar advena, and Pontedaria cordata. Comments: Other macroscopic subfossil records of Nymphaea from Indiana include Bristol Fen and Blueberry Bog in Elkhart County (Swinehart 1994; Swinehart & Parker 2000); Burket Bog and Little Chapman Bog in Kosciusko County (Swinehart & Parker 2000); and Yost Bog, Lagrange County (Swinehart & Parker 2000). Nuphar advena Ait.--Subfossil material: Seeds (INSM 71.12.002901.025; Swinehart #4B.4.16.17). Occurrence: Frequent in marl between the 80-110 cm depths. 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. Comments: Other macroscopic subfossil records of Brasenia schreberi from Indiana include Bristol Fen, Elkhart County (Swinehart 1994); Christensen Mastodont Site, Hancock County (Whitehead et al. 1982); Burket Bog, Little Arethusa Bog, and Little Chapman Bog in Kosciusko County (Swinehart & Parker 2000); Aker Mastodont Site, Marshall County (Swinehart unpubl. data); Dutch Street Bog and Svoboda Fen in Noble County (Swinehart & Parker 2000); and Ropchan Memorial Bog, Steuben County (Swinehart & Parker 2000). Family Caprifoliaceae cf. Triosteum sp.--Subfossil material: Seed (INSM 71.12.002901.028). Occurrence: A single specimen from the 90-100 cm depth. Habitat: Dry or moist woods. Comments: No other records are known from Indiana. KINGDOM ANIMALIA Phylum Mollusca Family Physidae Physa sayii Tappan.--Subfossil material: Shells (INSM #71.l0.2637.8-.9; Swinehart #4B.5.18.2). Occurrence: In marl; 100-120 cm. 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 1960). While Zimmerman (1960) reports that P. sayii prefers protected areas, Harmen & Berg (1971) found that it was most common in exposed areas. Goodrich et al. (1944) note that it can sometimes be found on wave-battered shores. Comments: Holocene subfossil records from the southern Great Lakes region include; Peoria County, Illinois Peoria County is a county located in the U.S. state of Illinois. As of 2000, the population was 183,433. Its county seat is Peoria, Illinois6. Geography According to the U.S. Census Bureau, the county has a total area of 1,634 km² (631 mi²). (Baker 1918), Logan County, Ohio Logan County is a county located in the state of Ohio, United States. As of 2000, the population was 46,005. The county seat is Bellefontaine.6 The county is named for Benjamin Logan, who fought Native Americans in the area. (Zimmerman 1960) and Kosciusko County, Indiana Kosciusko County is a county located in the U.S. state of Indiana. The county seat is Warsaw6. The county was formed in 1836. It was named after the Polish general Tadeusz Kosciuszko, who served in the American Revolutionary War, and then returned to Poland. (Swinehart & Parker 2000). While Zimmerman (1960) and Swinehart & Parker (2000) found many individuals throughout the Ohio and Indiana marl deposits, respectively, Baker (1918) found only one juvenile in Illinois. The species was infrequent at the Wilkinson site and restricted to the 100-120 cm depths. Physa sayii is presently common in northern Indiana in lakes and occasionally in streams (Goodrich et al. 1944). Family Lymnaeidae Lymnaea cf. L. humilis Say.--Subfossil material: Shells (INSM #71.10.2637.1-.7; Swinehart #4B.5.18.1). Occurrence: In marl between 80-110 cm. Also in silt at 140-150 cm. 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 et al. (1944) also report this species as inhabiting mud flats. Comments: Subfossil reports for this species in the southern Great Lakes region come from Blatchley & Ashley (1901) from marls taken from North Mud Lake, Fulton County, Indiana Fulton County is a county located in the U.S. state of Indiana. As of 2000, the population was 20,511. The county seat is Rochester6. History Fulton County was formed in 1836. It was named for Robert Fulton, inventor of the steamboat. ; Baker (1920) from Flat Rock River, Bartholomew County, Indiana Bartholomew County is a county located in the U.S. state of Indiana, and determined by the U.S. Census Bureau to include the mean center of U.S. population in 1900. As of 2000, the population was 71,435. The county seat is Columbus. ; Swinehart (1995) from Elkhart County, Indiana Elkhart County is a county located in the U.S. state of Indiana. As of 2000, the population was 182,791. The county seat is Goshen. Geography According to the U.S. Census Bureau, the county has a total area of 1,212 km² (468 mi²). (misidentified as L. palustris); and Swinehart & Parker (2000) from Kosciusko County, Indiana. Blatchley & Ashley (1901) found the species occupying 12% of the total mollusks in the Fulton County deposit. Swinehart (1995) found it to be abundant in the Elkhart County deposit but infrequent in the Kosciusko County deposit. It was infrequent throughout the marl layer in the present study. Similar species under the generic synonyms of Galba, Fossaria and Stagnicola are common in Holocene marls of the region (see Baker 1918; La Rocque 1952; La Rocque & Forsythe 1957; Reynolds 1959; Zimmerman 1960). Goodrich et al. (1944) recognize two subspecies subspecies, also called race, a genetically distinct geographical subunit of a species. See also classification. in Indiana'a current mollusk fauna, L. humilis modicella and L. humilis rustica, but records of their current distribution in the State are incomplete. Lymnaea haldemani Binney.--Subfossil material: Shells (INSM #71.10.2637.10; Swinehart #4B.5.18.9). Occurrence: In marl in the 80-90 cm and 100-110 cm depths. 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 waterlilies (Zimmerman 1960). It has also been found on rotting Typha leaves (Harmen & Berg 1971). This species is always found in limited numbers (Zimmerman 1960). Comments: The only other known Holocene subfossil record for this species in the southern Great Lakes region is from Zimmerman (1960) from Logan County, Ohio. The fragile nature of the shell along with the fact that living specimens of this species are rarely found in large numbers limits palaeoecological inferences regarding post-glacial populations and distribution. Shells, always fragmentary, were rare in the Wilkinson deposit. Lymnea haldemani is not known to exist presently in Indiana. Family Planorbidae Helisoma anceps (Menke).--Subfossil material: Shells (INSM #71.10.2637.11-.16; Swinehart #4B.5.18.4). Occurrence: Frequent in marl and silt between the 60-150 cm depths. 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. Comments: Holocene subfossil records for the southern Great Lakes region include Mahomet, Illinois (Baker 1918), McLean County, Illinois McLean County is a county located in the U.S. state of Illinois. It is included in the Bloomington, Illinois-Normal, Illinois Metropolitan Statistical Area. As of 2000, the population was 150,433. Its county seat is Bloomington, Illinois6. (Baker 1930), Fulton County, Indiana (Blatchley & Ashley 1901), Bartholomew County, Indiana (Baker 1920), Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000), Ross County, Ohio Ross County is a county located in the state of Ohio, United States established on August 20, 1796. As of the 2000 census, the population was 73,345. Its county seat is Chillicothe6, the first capital of Ohio. (Reynolds 1959) and Logan County, Ohio (Baker 1920; Zimmerman 1960). The species is relatively abundant in the reported deposits. Probably common in the lake region of Indiana at present. Helisoma campanulata (Say).--Subfossil material: Shells (INSM #71.l0.2637.17-.19); Swinehart #4B.5.18.11). Occurrence: Frequent in marl between the 80-130 cm depths. 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, Nymphaeal Pontedaria, and Decodon zones of a basic bog lake in Ohio. Comments: Holocene subfossil records for H. campanulata in the southern Great Lakes region come from Mahomet, Illinois (Baker 1918), Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000), and Logan County, Ohio (Baker 1920; Zimmerman 1960). Although present throughout many marl deposits, this species is usually found in relatively low numbers at any given depth. Present ly, H. campanulata is common in the lake area of Indiana (Goodrich et al. 1944). Gyraulus cf. G. parvus (Say).--Subfossil material: Shells (INSM #71.10.2637.20-.26; Swinehart #4B.5.18.7). Occurrence: Abundant in marl between the depths of 60-140 cm. Rare between 140-165 cm. 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 in all but the Larix and Quercus-Fagus-Ulmnus zones of an Ohio peatland. Comments: Records of Holocene subfossils of C. parvus/altissimus in the southern Great Lakes region include McLean County, Illinois (Baker 1930), Fulton County, Indiana (Blatchley & Ashley 1901), Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000), Madison County, Ohio Madison County is a county located in the state of Ohio, United States. As of the 2000 census, the population was 40,213. Its county seat is London6 and is named for James Madison, President of the United States when the county was established on March 1, 1810. (La Rocque 1952), Ross County, Ohio (Reynolds 1959), and Logan County, Ohio (Zimmerman 1960). Gyraulus parvus/altissimus is usually very abundant in post-glacial marl deposits. Presently found throughout Indiana (Goodrich et al. 1944). Promenetus exacuosus (Say).--Subfossil material: One shell. Occurrence: In marl, 100-110 cm. Habitat: Found in quiet waters associated with many types of substrates (Zimmerman 1960), but mostly over sand and mud with thick vegetation (Reynolds 1959). La Rocque (1952) reports that it is most common in marshy areas or mud flats with pH's from 7-7.6. Similarly, Harmen & Berg (1971) found it most commonly in cattail cattail or reed mace, any plant of the genus Typha, perennial herbs found in almost all open marshes. The cattail (also called club rush) has long narrow leaves, sometimes used for weaving chair seats, and a single tall stem bearing two marshes on the undersides of dead, floating Typha leaves. Dexter (1950) found it abundantly in the Nymphaea/Pontedaria, Potamogeton, and Decodon zones. It is locally associated with the algae algae (ăl`jē) [plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that Cladophora and Oedogonium (Reynolds 1959). Zimmerman (1960) reports that P. exacuosus is most common to cooler waters, and dense vegetation favors the lower temperatures that it seems to prefer. Comments: Holocene subfossil records for P. exacuosus in the southern Great Lakes region include Fulton County, Indiana (Blatchley & Ashley 1901), Madison County, Ohio (La Rocque 1952), Ross County, Ohio (Reynolds 1959), and Logan County, Ohio (Baker 1920, Zimmerman 1960). Although its presence is not uncommon in Holocene marls, it usually occurs in small numbers. Goodrich et al. (1944) assumed that it is currently found throughout Indiana. Family Hydrobiidae Amnicola limosa (Say).--Subfossil material: Shells (INSM #71.10.2637-27-31; Swinehart #4B.5.18.13). Occurrence: Abundant in marl between 70-130 cm. 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 brack·ish adj. 1. Having a somewhat salty taste, especially from containing a mixture of seawater and fresh water: "You could cut the brackish winds with a knife/Here in Nantucket" 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/Myriophyllum, Nymphaea/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. Comments: Holocene subfossil records of A. limosa/leightoni in the southe rn Great Lakes region include Mahomet, Illinois (Baker 1918), McLean County, Ohio (Baker 1930), Fulton County, Indiana (Blatchley & Ashley 1901), Bartholomew County, Indiana (Baker 1920), Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000), Ross County, Ohio (Reynolds 1959), and Logan County, Ohio (Zimmerman 1960). This species is usually very abundant in Holocene marl deposits. Presently found throughout Indiana, especially in the lake area (Goodrich et al. 1944) Amnicola lustrica Pilsbry.--Subfossil material: Shells (INSM #71.10.2637.32-.34; Swinehart #4B.5.18.10). Occurrence: Infrequent in marl between the depths of 70-120 cm. 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 filamentous /fil·a·men·tous/ (fil?ah-men´tus) composed of long, threadlike structures. filamentous composed of long, threadlike structures. algae (Zimmerman 1960). Comments: Holocene records for A. lustrica include Fulton County, Indiana (Blatchley & Ashley 1901), Bartholomew County, Indiana (Baker 1920), Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000), and Logan County, Ohio (Baker 1920; Zimmerman 1960). It is presently found in the lake area of Indiana. Family Valvatidae Valvata sincera Say.--Subfossil material: Shells (INSM #71.10.2637.42-.44; Swinehart #4B.5.18.12). Occurrence: Frequent in marl; 110-140 cm. Habitat: This species is reported as being primarily from deep water (5-6 in), usually below 3 m in depth, of cold lakes with limited vegetation (Zimmerman 1960). Harmen & Berg (1971) found it at a depth of 5 in. Comments: Holocene subfossil records for V. sincera include Urbana, Illinois (Baker 1920), Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000) and Logan County, Ohio (Zimmerman 1960). A similar species V. lewisi was reported for Madison County, Ohio by La Rocque (1952). Valvata sincera is often found in association with V. tricarinata but in much fewer numbers. Valvata sincera is presently common in lakes in northern Indiana. Valvata tricarinata (Say).--Subfossil material: Shells (INSM #71.10.2637.35-.41; Swinehart #4B.5.18.8). Occurrence: Abundant in marl between the 60-140 cm depths. Occasional in silt and outwash between 140- 165 cm. Habitat: Inhabits a wide variety of conditions but is most common to lakes. Harmen & Berg (1971) report that most specimens from lotic lo·tic adj. Of, relating to, or living in moving water. [From Latin l conditions are depauperate de·pau·pe·rate adj. 1. Arrested in growth or development; stunted. 2. Severely diminished; impoverished: "But there were no pleasures in Australia. . 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. Comments: Holocene subfossils of V. tricarinata in the southern Great Lakes region have been reported for Urbana, Illinois (Baker 1920), Mahoinet, Illinois (Baker 1920), McLean County, Illinois (Baker 1930), Bartholomew County, Indiana (Baker 1920) Elkhart County, Indiana (Swinehart 1995), Kosciusko County, Indiana (Swinehart & Parker 2000), Logan County, Ohio (Baker 1920; Zimmerman 1960), and Ross County, Ohio (Reynolds 1959). This is one of the most widely distributed and abundant mollusks of Holocene marls. Goodrich et al. (1944) speculate that this was one of the first aquatic mollusks to re-invade newly deglaciated areas. It presently occurs throughout Indiana (Goodrich et al. 1944). Family Endodontidae Helicodiscus parallelus (Say).--Subfossil material: One shell (Swinehart #4B.5.18.3). Occurrence: In marl, 60-70 cm. Habitat: Goodrich et al. (1944) report this species as being most common in flood plains. Comments: Accounts of this species in other Holocene marls are not known. Only a single specimen was recovered from the Wilkinson site. The species, presently, is distributed throughout Indiana. Family Sphaeridae Pisidium sp.--Subfossil material: Shells (INSM #71.10.2637.45.50; Swinehart #4B.5. 18.6). Occurrence: Abundant in marl between 60-140 cm. Occasional in silt and outwash between 140-165 cm. Habitat: Variable. Comments: Common in Holocene marls. Sphaerium sp.--Subfossil material: Shells (INSM #71.l0.2637.51-.54; Swinehart #4B.5.18.14). Occurrence: Frequent in marl and silt between 60-150 cm. Habitat: Variable. Comments: Common in Holocene marls. Family Unionidae cf. Uniomerus tetralasmus (Say).--Subfossil material: Single specimen (both valves) (INSM #71.10.2637.). Occurrence: In marl; 60-70 cm. Habitat: Common in ponds, small creeks, and headwaters of larger streams in mud or sand (Cummings & Mayer 1992). May withstand desiccation des·ic·ca·tion n. The process of being desiccated. des  ic·ca and, as a result, is often found where other mussels are
absent (Cummings & Mayer 1992). Comments: There are no known
Holocene subfossil records for this species in the Midwest.
Phylum phylum, in taxonomy: see classification. Chordata (Subphylum subphylum /sub·phy·lum/ (sub´fi-lum) pl. subphy´la a taxonomic category between a phylum and a class. sub·phy·lum n. pl. Vertebrata) Class Ayes Order Anseriformes Family Anatidae Branta canadensis, (Canada Goose).--Subfossil material: Left ulna ulna: see arm. , distal 2/5 (INSM #71.3.143.1). Habitat: Historically, the Canada goose was a common migrant and permanent resident of the state. It favors larger bodies of water adjacent to extensive marshland, but may be found on nearly any aquatic habitat (Mumford & Keller 1984). Class Mammalia Order Rodentia Family Castoridae Castoroides ohioensis, (giant beaver).--Subfossil Material: Right femur, lacking medial condyle condyle /con·dyle/ (kon´dil) a rounded projection on a bone, usually for articulation with another bone.con´dylar con·dyle n. area; recovered in two pieces (INSM #71.3.128). Occurrence: Recovered on surface from soils dug from trench. Because trenching extended only down into the upper few inches of marl, and because the femur was impacted with mollusk-rich marl, it is likely that the femur originally occurred within the upper few inches of the marl level, likely within the 60-70 cm depth. Habitat: Because the species is extinct its habitat preference and habits are not known for sure. However, the functional morphology of skeletal elements (discussed above) and ecological associations (discussed below) do provide some insight. Comments: Including the present, there are 16 credible published records for Indiana: Boone County, Jamestown (Hay 1912); Cass County, Logansport (Martin 1912; Hay 1912); Daviess County, Prairie Creek Site (Tomak 1975); Dekalb County, unspecified locality (Cahn 1932); Grant County, Fairmount (Hay 1912, 1912b); Han cock County, Greenfield vicinity (Moore 1893); Hancock County, Christensen mastodont locality (Graham, Holman and Parmalee 1983); Madison County, Summitville (Hay 1912); Martin County, Shoals (Adams 1946); Miami County, Macy (Hay 1923); Newton County, Mount Ayr (Cahn 1932); Randolph County, Winchester/Union City (Moore 1890, 1893); St. Joseph County St. Joseph County is the name of several counties in the United States:
Castor canadensis Castor canadensis (syn. C. fiber) see beaver. , (Beaver).--Subfossil material: Anterior lumbar/posterior thoracic vertebra vertebra /ver·te·bra/ (ver´te-brah) pl. ver´tebrae [L.] any of the 33 bones of the vertebral (spinal) column, comprising 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal vertebrae . , neural arch neural arch n. See vertebral arch. only, lacking spine (INSM #71.3.143.2). Habitat: In Indiana, the beaver is most abundant in the lakes, marshes, and streams of the northern part of the state (Mumford & Whitaker 1982). Comments: The vertebra was from the Thoracic T-11 through T-14, or lumbar L-1 or L-2 part of the series. A subadult was represented. It is interesting that remains of the modern beaver occurred stratigraphically earlier on the Wilkinson locality than those of the giant beaver. Order Artiodactyla Large Artiodactyla, sp. indet.--Subfossil material: Molariform enamel portion (INSM #71.3.143.3). Comments: Crown enamel portion from hypsodont molariform tooth that includes one fossette. The enamel is relatively unworn un·worn adj. 1. Not worn out or worn away. 2. Not worn before; new. 3. Not stale or overused; fresh. unworn Adjective 1. . DISCUSSION Geologic history.--The Wilkinson Site, began as a raging meltwater melt·wa·ter n. Water that comes from melting snow or ice. meltwater Noun melted snow or ice Noun 1. river that deposited clean, sorted glacial drift in a channel on the Packerton Moraine. As the meltwaters slowed, a few organic remains indicative of the surrounding forest composition were left behind in the outwash. Finally, stagnation Stagnation A period of little or no growth in the economy. Economic growth of less than 2-3% is considered stagnation. Sometimes used to describe low trading volume or inactive trading in securities. Notes: A good example of stagnation was the U.S. economy in the 1970s. of the water resulted in settling of finer materials, primarily silts, which blanketed the outwash. A shallow lake remained, and an inlet and outlet were maintained by Spring Creek, which provided ample drainage and oxygen- and nutrient-rich water. It may also have been the source of occasional conifer conifer (kŏn`ĭfûr) [Lat.,=cone-bearing], tree or shrub of the order Coniferales, e.g., the pine, monkey-puzzle tree, cypress, and sequoia. Most conifers bear cones and most are evergreens, though a few, such as the larch, are deciduous. remains, which indicate a surrounding forest of Picea glauca, Abies balsamea and Larix laricina. Infrequent remains of charred wood suggest occasional fires. The waters feeding Wilkinson Lake were nearly saturated with bicarbonates brought into solution via contact with the characteristically lime-rich glacial till. Because the marl in the basin did not appear to be formed wholly or partially by the calcium carbonate calcium carbonate, CaCO3, white chemical compound that is the most common nonsiliceous mineral. It occurs in two crystal forms: calcite, which is hexagonal, and aragonite, which is rhombohedral. tests of Chara thalli thal·li n. A plural of thallus. (none were recovered), it can be assumed that the primary source of the marl precipitate was the uptake of [CO.sub.2] by phytoplankton phytoplankton Flora of freely floating, often minute organisms that drift with water currents. Like land vegetation, phytoplankton uses carbon dioxide, releases oxygen, and converts minerals to a form animals can use. and littoral littoral /lit·to·ral/ (lit´ah-r'l) pertaining to the shore of a large body of water. littoral pertaining to the shore. vegetation, or possibly the flow of sub-terranian aquifers into the lake. The shallow nature of the lake meant that the trophogenic zone extended to the substrate throughout, and carbon dioxide carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. levels were probably low throughout the water column. This would hinder most marl precipitates from being brought back into solution as bicarbonate. The Castoroides femur occurred at a level when coarse gravel had also been deposited, possibly accounting for the stream transport and/or scattering of unburied skeletal remains. (This was also a period when molluscan mol·lus·can also mol·lus·kan adj. Of or relating to the mollusks. n. A mollusk. remains were becoming sparse, suggesting at least periodic drying of the habitat. A gradual increase in Najas and Scirpus remains coincides with the decrease in mollusks). Vegetation.--The early submergent flora was composed of pondweeds such as Potamogeton pusillus and Najas flexilis. Both are characteristic of mineral-rich waters. The Najas eventually became extremely abundant, at least as evidenced by the abundant remains of its achenes in the sediment. While Najas and additional submergent vegetation, such as Potamogeton praelongus, became important members of the flora, emergent vegetation began to appear. Nymphaea odorata, Nuphar advena and Brasenia schreberi, because of the shallow depth, probably grew across the entire water body. As vegetative vegetative /veg·e·ta·tive/ (vej?e-ta?tiv) 1. of, pertaining to, or characteristic of plants. 2. concerned with growth and nutrition, as opposed to reproduction. 3. remains and marl began to fill-in the shallower margins of Wilkinson Lake, bulrushes (Scirpus validus and Scirpus acutus) took hold and colonized Colonized This occurs when a microorganism is found on or in a person without causing a disease. Mentioned in: Isolation . While most were probably restricted to the marginal wetlands, many probably invaded the shallow waters of the open lake. It is this marsh environment where the giant beaver lived, died, and was buried. Eventually, the open water filled-in entirely, and a sedge- and bulrush-dominated wetland remained. Spring Creek maintained its presence in the area, and probably changed course many times as it traversed the sedge meadow. The creek carried sediments, and sometimes gravels, that were deposited along its course. During spring snowmelt snow·melt n. 1. The runoff from melting snow. 2. A period or season when such runoff occurs: streams that flood during snowmelt. , fast moving waters would carry large gravels into the wetland. This may explain the curious abundance of coarse gravel in strictly limnic sediments below the marl/peat interface. Mollusks.--Based on modern analogues, it is concluded that the molluscan fauna encountered in the marls of the Wilkinson site indicates the area was once a relatively small, shallow, wind-sheltered lake with moderate to heavy vegetation cover and the presence of muddy or marly marl n. A crumbly mixture of clays, calcium and magnesium carbonates, and remnants of shells that is sometimes found under desert sands and used as fertilizer for lime-deficient soils. tr.v. flats. The mollusks give some indication of the water quality in Wilkinson Lake. Based on ecological amplitudes provided by Harmen & Berg (1971) the composition of the mollusk assemblage at Wilkinson Lake suggests that the water probably maintained pH values of 7-8.5, alkalinity al·ka·lin·i·ty n. The alkali concentration or alkaline quality of a substance that contains alkali. alkalinity 1. the quality of being alkaline. 2. values of 100- 150 ppm, and dissolved oxygen values of 10-14 ppm. The decline of mollusks at the end of marl production is attributed to the closure of open water habitat and the transition to a sedge meadow. Given the position and age of the radiocarbon dates, Wilkinson Lake and the subsequent sedge meadow probably extinguished long before the demise of the boreal forest. By far the most abundant mollusks throughout the marls of the Wilkinson deposit were Valvata tricarinata, Gyraulus parvus, Amnicola limosa and Pisidium spp. Similarly, Swinehart (1995, unpubl. B.A. thesis, Goshen College) found these species to be the most abundant throughout the Bristol Fen deposit in Elkhart County, Indiana. Reynolds (1959) and Zimmerman (1960) also found Valvata tricarinata, A. leightoni (cf. G. limosa) and Gyraulus altissimus (cf. G. parvus) as being among the most abundant. All of these species indicate a shallow, weedy lake. The estimated number of mollusks for each 0.1 [m.sup.3] volume for each depth increased rapidly, then sharply at 120 cm to over 168,000 (Fig. 3) before decreasing again to zero near the 70 cm depth. The 120 cm depth also had the greatest richness of mollusks. It is assumed that the great abundance and richness of mollusk taxa at this level is a function of ample food and high habitat heterogeneity. As the water became shallower, aquatic vegetation, including algae ( an important food source), probably increased, creating both a variety of food items as well as structure (e.g., submergent, floating, and emergent vegetation). Continued shallowing of the water and closing of open water probably reduced light and oxygen levels sufficiently to rob many species of suitable food and habitat. A few conclusions can be made about conditions in the lake from some of the less abundant species. Valvata sincera dropped out of the assemblage early in the filling of Wilkinson Lake. Since this species has been noted as preferring deeper water, its demise may have been facilitated early by sediment in-filling. The appearance of Helicodiscus parallelus at the marl/peat interface is indicative of a transition from open water to wetland conditions. The near absence of unionid mussels from the deposit may indicate that few fishes were present, as unionids usually require fishes as hosts for their parasitic larvae Larvae, in Roman religion Larvae: see lemures. . Correspondingly, no fish scales or fish bones were recovered from the deposit. CONCLUSIONS Early post-glacial lakes.--The discovery of limnic deposits from lakes and wetlands that have long ago extinguished (so long ago that their aquatic origins are often topographically obscured), not only emphasizes the reality of classic hydrarch hy·drarch adj. Originating in a wet habitat, such as a pond. Used of an ecological succession. succession (despite heated objections to it on the part of many ecologists), it also provides an invaluable archive for understanding the palaeoenvironments inhabited by extinct organisms. Moreover, such deposits help in reconstructing post-glacial biotic biotic /bi·ot·ic/ (bi-ot´ik) 1. pertaining to life or living matter. 2. pertaining to the biota. bi·ot·ic adj. 1. Relating to life or living organisms. migrations and successions. Based on studies of the Wilkinson deposit and other similar deposits in the southern Great Lakes region, it appears that several species of organisms were ubiquitous pioneers to newly created, late-glacial lakes and ponds. With regard to plants, members of the genus Potamogeton as well as Najas flexilis are particularly common. In marls, the mollusks, Valvata tricarinata, Gyraulus parvus, Amnicola limosa and Pisidium spp. are almost always present. While these species may be indicative of g eneral conditions in a given wetland, it is the infrequent or scattered taxa that may be of more ecological interest because they may indicate environmental thresholds or ecotones for their respective taxa. Descriptive and numerical investigations on the mollusk communities of the lakes and wetlands of Indiana are few and insufficient not only in terms of documenting extant taxa, but also as a resource for palaeoecological inference. Much research on the existing mollusk faunas and their relationship to vertebrate communities, predominating vegetation, wetland hydrology hydrology, study of water and its properties, including its distribution and movement in and through the land areas of the earth. The hydrologic cycle consists of the passage of water from the oceans into the atmosphere by evaporation and transpiration (or and morphometry mor·phom·e·try n. Measurement of the form of organisms or of their parts. mor  pho·met , substrate type, and water chemistry
is recommended. These data will not only add to our knowledge of extant
communities, but it will also facilitate inferences about
palaeoenvironments and their succession. Additionally, further research
on the sub-fossils in the marl deposits of Indiana, and elsewhere, would
provide more precise documentation and understanding of late-Pleistocene
and Holocene biogeography BiogeographyA synthetic discipline that describes the distributions of living and fossil species of plants and animals across the Earth's surface as consequences of ecological and evolutionary processes. . The habitat of Castoroides ohioensis. The Wilkinson beaver died near the time when its species went extinct, circa 10,000 years ago (see Caha 1932). The Wilkinson site at the time the specimen died was a mineral-rich, wet meadow, dominated by bulrushes. Cattails, although not evidenced by subfossils, were probably also present in appreciable numbers. The surrounding forest was dominated by white spruce, balsam fir, and tamarack, with birch and aspen probably occupying disturbed sites and lakeshores. Many authors believe that a reduction or loss of the preferred habitat of the giant beaver at the end of the Pleistocene and perhaps its overspecialization, including the inability to disperse readily and to build dams, contributed to its extinction (Stirton 1965; Kurten & Anderson 1980; Harington 1986; Holman 1995). The question of habitat loss can be addressed by studying palaeoenvironments and comparing the ancient habitats to potential modern analogues. Based on the subfossil analysis of the Wilkinson sight, functional analogues of the habitat of the giant beaver have existed from the time when it flourished to the present day. All of the taxa found at the Wilkinson site, are extant and common members of modern shallow-water wetlands. Only the boreal conifers have significantly changed their range and distribution, but even these are still found commonly in the northern Midwest. Moreover, suitable wetland habitats for giant beaver have increased, not decreased, since the retreat of the last glaciers, due in large part to colonization of barren outwash channels by emergent vegetation as well as ecological succession and consequent in-filling of deeper water bodies. At the time of settlement of Indiana, shallow wetlands were so plentiful that in the spring of the year one could put a canoe in at the area that is now Fort Wayne and travel all the way to Lake Michigan without having to portage Portage (1, 2 pôr`təj; 3 pôr`tĭj). 1 Town (1990 pop. 29,060), Porter co., NW Ind., a suburb of Gary, on Lake Michigan; inc. 1959. more than a mile or two. It would seem then, that habitat and food loss are not likely factors in the extinction of the giant Beaver. The exact reason for the extinction of the giant beaver and the other North American "ice age" megafauna meg·a·fau·na n. (used with a sing. or pl. verb) Large or relatively large animals, as of a particular region or period, considered as a group. meg is not known. However, there are two changes that occurred at about the time the megafauna began to go extinct; climate and the immigration immigration, entrance of a person (an alien) into a new country for the purpose of establishing permanent residence. Motives for immigration, like those for migration generally, are often economic, although religious or political factors may be very important. of humans to North America. The changes associated with transitions from interglacial in·ter·gla·cial adj. Occurring between glacial epochs. n. A comparatively short period of warmth during an overall period of glaciation. climates to glacial climates, and back again, do not seem to be a logical explanation for the extinctions, because such glaciation cycles have occurred many times during the Quaternary quaternary /qua·ter·nary/ (kwah´ter-nar?e) 1. fourth in order. 2. containing four elements or groups. qua·ter·nar·y adj. 1. Consisting of four; in fours. with apparently no major effect on the populations of the North American megafauna Megafauna are animals whose average adult weight is over 100 pounds (44 kg). Extant and recently extinct (in the Pleistocene) megafauna of North America (north of Mexico) are listed here. . Therefore, the only apparent, new variable that occurred during the last glaciation is the appearance of humans. Whether people negatively affected the megafauna via hunting, introduction of disease, or both, is still a subject of much controversy. ACKNOWLEDGMENTS We thank Mr. Luke Hunt, Whitko High School, for bringing the Castoroides remains to our attention. Monte and his father Galen Wilkinson kindly allowed recovery on their property, assisted greatly with the operation of a backhoe, and donated all materials to the Indiana State Museum. We also thank numerous staff and volunteers of the Indiana State Museum for making the difficult recovery in sub-freezing weather possible. Volunteer Vein Swanson undertook considerable effort to rewash and sort the biotic concentrate that facilitated the present study. LITERATURE CITED Adams, WR. 1946. Archaeological survey of Martin County, Pp. 197-198, In Indiana History Bulletin 23(6). Baker, F.C. 1918. Post-glacial molluska from the marls of central Illinois. Journal of Geology 26: 659-671. Baker, F.C. 1920. Pleistocene mollusca from Indiana and Ohio. Journal of Geology 28:439-457. Baker, F.C. 1930. A new record of Castoroides ohioensis from Illinois. Science 71:389. 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Holman, J.A. 1975. Michigan's fossil vertebrates. Publications of the Museum, Michigan State University Michigan State University, at East Lansing; land-grant and state supported; coeducational; chartered 1855. It opened in 1857 as Michigan Agricultural College, the first state agricultural college. , Educational Bulletin No. 2. 54 pp. Holman, J.A. 1995. Ancient Life of the Great Lakes Basin The Great Lakes Basin consists of the Great Lakes and the surrounding lands of the states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin in the United States, and the provinces of Ontario and Quebec in Canada, whose direct runoff and . The University of Michigan (body, education) University of Michigan - A large cosmopolitan university in the Midwest USA. Over 50000 students are enrolled at the University of Michigan's three campuses. The students come from 50 states and over 100 foreign countries. Press, Ann Arbor. 287 pp. Jackson, S.T. & D.R. 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Figure 3
Approximate number of mollusk shell sper 0.1 [m.sup.3] of bulk
sediment at 10 cm intervals throughout the Wilkinson sediment
profile.
Depth interval Estimated number of
(10 cm increments) molluscs
per 1.0 x
[10.sup.5] [cm.sup.3]
of sediment
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 50
9 7680
10 18872
11 43545
12 168,780
13 30764
14 26761
15 20600
16 3794
17 10
18 0
Note: Table made from bar graph
[Figure 2 omitted] |
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