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Early evolution, diversification, and geographic distribution of the suborders constituting the mammalian order artiodactyla.

97 EARLY EVOLUTION, DIVERSIFICATION, AND GEOGRAPHIC DISTRIBUTION OF THE SUBORDERS CONSTITUTING THE MAMMALIAN ORDER ARTIODACTYLA

Artiodactyla comprises three extant suborders and perhaps five unnamed extinct ones.

1 (basalmost artiodactyls [paraphyletic]: diacodexid, primitive [unassigned, some dichobunine] dichobunid dichobunoids): Ml-3 (Ms) bunodont, triangular; metaconule unenlarged; no hypocone (Old World [OW] origin).

2 (some more-derived dichobunines plus lantianiine, some eurodexine dichobunids): Ms quadrate, incipiently selenodont; hypocone distinct; metaconule in latter two groups still connected to protocone by postprotocrista, interrupting transverse valley (TV) (OW).

3 (most-derived dichobunoids [dichobunine Dichobune, hyperdichobunine dichobunids; might include other dichobunids with quadrate hypoconiferous Ms] plus caenotheriids); Ms relatively selenodont, quadrate; tritubercular distal lobe with distinct metacone, metaconule, and hypocone; TV continuous; paraconule reduced/lost (OW).

4 (entelodondds): Ms bunodont, quadrate, with tritubercular distal lobes, uninterrupted TVs, but paraconules unreduced (OW origin).

Bunodonta/Suiformes (raoellids, cebochoerids, choeropotamids [inc. haplobunodontids], palaeochoerids, sanitheriids, suids, tayassuids, hippopotamids, anthracotheriids, anoplotheriids [inc. dacrytheriids], mixtotheriids, dichodontids, xiphodontids, amphimerycids, maybe some dichobunines): Ms primitively bunodont, quadrate, each with bitubercular distal lobe bearing enlarged metaconule as distolingual cusp. (OW origin, except tayassuids).

Primitively, those suborders lack coossified hind-limb elements.

Tylopoda (oromerycids, camelids, oreodontoids, protoceratids): Ms primitively bunoselenodont, quadrate, each with mesostyle plus bitubercular distal lobe bearing enlarged metaconule as distolingual cusp; ectomesocuneiform (North American origin).

5 (Diacodexis secans, D. minutus, leptochoerids, helohyids [inc. achaenodontids], homacodontids, bunomerycids, hypertragulids [inc. Simimeryx, Parvitragulus, hypisodontids]): Ms primitively bunodont; tibia, fibula coossified distally; ectomesocuneiform (North America).

Pecora/Ruminantia (Limeryx, Asiohomacodon, praetragulids, archaeomerycids, lophiomerycids, leptomerycids, tragulids, "pecorans"): Ms primitively bunoselenodont, but (unlike hypertragulids) with mesostyles; tibia, fibula primitively unfused or coossified proximally; cubonavicular; primitively, no ectomesocuneiform (OW origin, except leptomerycids).

E.B. Lander. Paleo Environmental Associates, Inc., 2248 Winrock Avenue, Altadena, CA 910013205, and Research Associate, Natural History Museum of Los Angeles County Department of Vertebrate Paleontology, 900 Exposition Boulevard, Los Angeles, CA 90007

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Title Annotation:SATURDAY ABSTRACTS IN PROGRAM ORDER
Author:Lander, E.B.
Publication:Bulletin (Southern California Academy of Sciences)
Article Type:Author abstract
Geographic Code:1USA
Date:Aug 1, 2014
Words:300
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