Pachysuchus
Dubious Early Jurassic dinosaur originally misidentified as a phytosaur.
Pachysuchus is a dubious genus of early sauropodomorph dinosaur from the Early Jurassic of China. Its remains consist of a poorly preserved partial snout, first described in 1951 by paleontologist Yang Zhongjian (also known as C.C. Young) from the Lower Lufeng Series in Yunnan. The type and only species is Pachysuchus imperfectus. The genus name means "thick crocodile," while the species name translates to "imperfect" in Latin. Young originally identified the snout as belonging to a phytosaur, a group of crocodile-like reptiles with long snouts that were common in the Triassic but are otherwise unknown from the Jurassic, as they are thought to have gone extinct during the Triassic-Jurassic extinction event. The original snout was later lost, and Young's initial identification was questioned due to the specimen's poor preservation and its Jurassic age. In 2012, Paul M. Barrett and Xu Xing relocated the holotype (specimen IVPP V 40) and identified it as belonging to an indeterminate basal sauropodomorph dinosaur. They concluded that the holotype lacks any unique features or unique combination of features, and while it differs from the snouts of other Early Jurassic Chinese sauropodomorphs, these differences could be due to its poor preservation, making Pachysuchus a nomen dubium.
Quick Facts
- Taxon
- Pachysuchus
- Type Species
- Pachysuchus imperfectus
- Type Species Authority
- Young, 1951
Facts from the source article.
Lore & Background
Pachysuchus was originally described by Yang Zhongjian (C.C. Young) in 1951 based on a poorly preserved partial rostrum from the Lower Lufeng Series in Yunnan. Young identified the rostrum as that of a phytosaur, a long-snouted crocodile-like crurotarsan. Phytosaurs were common in the Triassic but are thought to have gone extinct during the Triassic-Jurassic extinction event, making their presence in Jurassic beds unusual.
Reader's Guide
The significance of Pachysuchus lies in its history of misidentification and its current status as a nomen dubium. The rostrum from which Young described the specimen had since been lost, and his first description had been questioned. In 2012, Paul M. Barrett and Xu Xing relocated the holotype (specimen IVPP V 40) and identified it as actually belonging to a taxonomically indeterminate basal sauropodomorph. According to Barrett and Xu, the holotype does not bear any unique features or a unique character combination; it differs from rostra of other Early Jurassic Chinese sauropodomorphs, but it cannot be ruled out that the differences are caused by its poor preservation. This makes Pachysuchus a nomen dubium, a name applied to a fossil that cannot be reliably assigned to a distinct taxon. Its legacy is a cautionary tale in paleontology about the challenges of identifying fragmentary fossils and the importance of re-evaluating historical specimens.
Did You Know?
- Pachysuchus was originally misidentified as a phytosaur by Yang Zhongjian in 1951.
- The generic name Pachysuchus translates to 'thick crocodile'.
- The holotype specimen, IVPP V 40, was relocated and reidentified as a basal sauropodomorph in 2012.
- Pachysuchus is considered a nomen dubium because its holotype lacks unique features.
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