| Antrodemus | |
|---|---|
 | |
| Holotype tail vertebra (above) compared to same ofAllosaurus (below) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Allosauridae |
| Genus: | †Antrodemus Leidy, 1870 |
| Species: | †A. valens |
| Binomial name | |
| †Antrodemus valens (Leidy, 1870) Leidy, 1873 | |
| Synonyms | |
| |
Antrodemus ("chamber bodied") is adubiousgenus oftheropoddinosaur from theUpper Jurassic, probably theMorrison Formation, ofMiddle Park,Colorado. It contains one species,Antrodemus valens, first described and named as a species ofPoekilopleuron byJoseph Leidy in 1870.
The first describedfossil specimen was a bone obtained secondhand byFerdinand Vandeveer Hayden in 1869 (original discoverer unknown). It came from Middle Park, nearGranby, Colorado, probably from Morrison Formation rocks. Hayden reported that several similar fossils had been identified as petrifiedhorse hooves.[1] Hayden sent his specimen to Joseph Leidy, who identified it as half of a tail vertebra, and tentatively assigned it to the European dinosaur genusPoekilopleuron asPoicilopleuron [sic]valens, based on the shared presence of a large medullary cavity. He identified the presence oftrabeculae inP.valens as a distinguishing character fromP.bucklandii but also noted that should better remains show more characters that could sufficiently distinguish the two taxa, it might be namedAntrodemus.[1] In 1873, he amended his description and identified the species asAntrodemus valens.[2]
In 1920,Charles W. Gilmore concluded that the tail vertebra namedAntrodemus by Leidy was indistinguishable from those ofAllosaurus and thatAntrodemus should be the preferred name because, as the older name, it had priority.[3]Antrodemus became the accepted name for this familiar genus for over fifty years untilJames Madsen published on the Cleveland-Lloyd specimens ofAllosaurus and concluded that theAllosaurus name should be used becauseAntrodemus was based on material with poor, if any, diagnostic features and locality information (for example, thegeological formation that the single bone ofAntrodemus came from is unknown).[4] Subsequent authors have agreed with this assessment and have consideredAntrodemus anomen dubium.[5][6]
The paleontological site that still in the present day presents the highest concentration of fossilised individuals ofAllosaurus fragilis is the Cleveland-Lloyd Dinosaur Quarry, now part of theJurassic National Monument inUtah. The first skeletal mount obtained out of the Quarry was extracted in the late 1930s/early 1940s and finally mounted in 1961 in Guyot Hall,Princeton University,Princeton,New Jersey, where it remained on display until 2024. For years, that skeletal mount was presented to the visitors under the taxonomic nameAntrodemus, before the specimens from the Cleveland-Lloyd Quarry were attributed toAllosaurus.
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