[D] Graculavus lentus [~/~]
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Ornithurae Cartinatae Ichtyornithiformes
Austin Chalk, Texas, US
Austinornis lentus (Cantino, Bryant, de Queiroz, Donoghue, Eriksson, Hillis and Lee 1999) > Graculavus lentus (Marsh, 1877) > Ichthyornis lentus (Marsh, 1880)
Unnamed ichthyornithiform (= Graculavus lentus)
YPM 1796 is a wellpreserved distal left tarsometatarsus.
Graculavus lentus (Marsh, 1877b) became Ichthyornis lentus in 1880 when Marsh also named two additional species, Ichthyornis validus and Ichthyornis tener (Marsh, 1880).
The name ‘‘lentus’’ Marsh, 1877b is converted and defined as the species that includes YPM 1796. With its clade address (sensu Cantino et al., 1999), the converted name of this species is ‘‘Austinornis lentus’’. The name was originally published in the combination ‘‘Graculavus lentus’’ (Marsh, 1877b) and later in the combination ‘‘ Ichthyornis lentus’’ (Marsh 1880).
Locality and horzion
Marsh (1880: 198) described the holotype specimen as collected by B. F. Mudge near Fort McKinney, Texas, in 1876. Brodkorb (1967: 178) specified that it was from the Austin Chalk from ‘‘Colling’’ County (misprint of Collin County; Parris and Echols, 1992) near Fort McKinney. There is no more precise stratigraphic or locality data available. Its provenance should be further investigated.
The holotype differs in nearly all anatomical features that could be compared between it and Ichthyornis dispar (as represented by referred YPM tarsometatarsi, i.e., YPM 1456, YPM 1464, YPM 1739, YPM 1771; see table 1 for the basis of referral). Unlike other specimens referred to Ichthyornis dispar, a slight groove extends proximally from the juncture of metatarsals II and III on the dorsal surface of the tarsometatarsus. (Clarke, 2004)