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Revision and re‐evaluation of the Early Jurassic dinosaurian ichnogenus Otozoum
Author(s) -
Rainforth Emma C.
Publication year - 2003
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/1475-4983.00320
Subject(s) - paleontology , geology , taxon , holotype , cladistics , taxonomy (biology) , biology , zoology , phylogenetic tree , biochemistry , gene
Otozoum moodii Hitchcock, 1847 is one of the classic Connecticut Valley ichnotaxa established by Edward Hitchcock between 1836 and 1865. The taxon is redescribed, and AC 4/1a re‐established as the holotype specimen. Otozoum minus and O. caudatum are synonymised with O. moodii . The syntypes of Kalosauropus pollex ( nomen nudum ) are described as O. pollex sp. nov. Cladistic, quantitative, and comparative methods of trackmaker identification suggest that Otozoum was made by a prosauropod dinosaur. In quantitative analyses, only those phalanges likely to contribute to footprint morphology were considered; claws were also excluded due to their highly variable styles of impression. Several diagnostic characters distinguish Otozoum from Brachychirotherium , Chirotherium , Batrachopus , Tetrasauropus , and Pseudotetrasauropus ; these ichnotaxa are probably attributable to crurotarsan archosaurs. Otozoum is found primarily in Hettangian strata of the Hartford, Deerfield, and Fundy rift basins of eastern North America; it is also present in the Early Jurassic Navajo Sandstone (Colorado Plateau, USA) and Clarens Formation (Lesotho). The taxon is unknown in older strata; Triassic material previously referred to Otozoum (including O. grandcombensis ) instead belongs in Pseudotetrasauropus . Correlation of sediments and comparison of faunal assemblages, particularly within the Newark Supergroup, suggest that the Otozoum trackmakers were restricted to arid environments.