Vertebrate footprints and invertebrate traces from the Chadronian (Late Eocene) of West Texas

An assemblage of footprints from a late Eocene (Chadronian) tuff in Presidio County, west Texas, constitutes the richest terrestrial ichnofauna yet to be reported from the North American Tertiary. It consists largely of the tracks of vertebrates, including turtles, large and small birds, and a variety of large and small mammals. In addition, two types of invertebrate traces are present. The turtle tracks
are attributed to two new ichnospecies, Chelonipus chadronicus and C. parvus, and are placed in the new morphofamily Chelonipedidae. Proposals are advanced for the overhaul of the present classification of avian tracks. The new morphofamilies Gruipedidae, Charadriipedidae, Avipedidae, and Anatipedidae are proposed. Emended diagnoses are formulated for the ichnogenera Gruipeda Panin and Avram, oArdeipeda Panin and Avram, Charadriipeda Panin and Avram, Avipeda Vialov, and Anatipeda Panin and Avram, and their type species. The new genus Fuscinapeda is proposed and its type species, OF. sirin (Vialov), emended. Three new species, Gruipeda calcarifera, OFuscinapeda meunierii and F texana, are proposed, and two other avian footprint morphotypes are also described.
Nineteen morphotypes of mammalian foo prints are distinguished. The majority are placed in new ichnogenera and species. These include Schyromorphipus oxypages, probably an insectivore; Zanclonychopus cinicalcator, a creodont; five carnivores, one (Tetrastoibopus pharos) surely and another (Falcatipes flori- formis) probably miacids, one probably a mus- telid (Phacelopus therates), and two probably amphicyonids (Axiciapes ferox and A. curuidigitatus); a likely mesonychian (Corymbipes superstes ); three types of perissodactyls, including a tapiroid (Apoxypus tessellatus ) and a
rhinocerotoid (Thrinaxopus hoplephoreus ); a problematic footprint, possibly also a perissodactyl or a creodont (Palimmecopus praecursor) two artiodactyls, a probable entelodont (Anoplotheriipus
zeuctus ) and camel-like tracks (Gamhapes hastatus ); four types of rodent tracks, of which two (Tricorynopus elaphrus and Ptyariopus aichmanticheirus, the latter considered to be an ischyromyid) are named. One footprint morphotype remains of uncertain systematic affinity. We emend the ichnogenus Bestiopeda Vialov and propose a new ichnogenus, Chelipus, to accommodate one of Vialov’s species no longer attributable to Bestiopeda. We offer emended diagnoses for the artiodactyl ichnogenera Pecoripeda Vialov, Odocoileinichnium Aramayo and Bianco, and oLamaichnium