"Coelosaurus" antiquus ("antique hollow lizard") is a dubious species of theropod dinosaurs. It was named by Joseph Leidy in 1865 for two tibiae found in the Navesink Formation of New Jersey.
| "Coelosaurus" antiquus Temporal range: Late Cretaceous, | |
|---|---|
 | |
| Holotype tibia | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Ornithomimosauria |
| Family: | †Ornithomimidae |
| Species: | †"Coelosaurus" antiquus |
| Binomial name | |
| "Coelosaurus" antiquus | |
| Synonyms | |
| |
This species was later reclassified as a member of the genus Ornithomimus in 1979 by Donald Baird and John R. Horner as Ornithomimus antiquus,[1] and this was followed by some later researchers.[2] However, others have not followed this classification, and have noted that there is no justification for the classification of the New Jersey specimens in a genus known only from western North America. David Weishampel in 2004 considered "C." antiquus to be indeterminate among ornithomimosaurs, and therefore a nomen dubium.[3]
In 1979, Baird and Horner discovered that the name "Coelosaurus" was preoccupied by another dubious taxon (based on a single vertebra), named Coelosaurus by an anonymous author now known to be Richard Owen in 1854.[3]
Ornithomimid material known from the Severn Formation of Maryland and the Mooreville Chalk and Blufftown formations of Alabama and Georgia have also been assigned to this species.[4] A specimen once assigned to Coelosaurus that was discovered in the Merchantville Formation of Delaware during the 1970s has since been assigned to "Cryptotyrannus".[5]