First discovered in the 1850s, Compsognathus longipes was the first theropod dinosaur known from a fairly complete skeleton, and also the smallest known non-avian dinosaur for over 130 years.
(A second specimen was also, briefly, the “first” aquatic non-avian dinosaur, but that’s another story.)
Living in what is now Europe during the late Jurassic, about 150 million years ago, it was a lightly built animal with long legs and a long tail, growing to around 1.2m long (~4′). Its hands seem to have had only two functional fingers, with the third being vestigial and possibly not even having a claw.
Skin impressions from about a third of the way along its tail show small bumpy scales – but since other compsognathids like Sinosauropteryx are known to have been covered in fur-like feathers, this likely means that just that particular region of Compsognathus’ body wasn’t fluffy.
Some of Compsognathus‘ diet is known for certain, since preserved gut contents show it fed on smaller vertebrates like lizards and rhynchocephalians. The remains of a lizard in the stomach of one specimen were even identified as belonging to a previously-unknown species, Schoenesmahl dyspepsia, with the dismembered nature of the skeleton suggesting Compsognathus tore its prey into bite-sized chunks in a similar manner to modern predatory birds.
References:
- Conrad, Jack L. “A new lizard (Squamata) was the last meal of Compsognathus (Theropoda: Dinosauria) and is a holotype in a holotype.” Zoological Journal of the Linnean Society 183.3 (2018): 584-634. https://doi.org/10.1093/zoolinnean/zlx055
- Gishlick, Alan D., and Jacques A. Gauthier. “On the manual morphology of Compsognathus longipes and its bearing on the diagnosis of Compsognathidae.” Zoological Journal of the Linnean Society 149.4 (2007): 569-581. https://doi.org/10.1111/j.1096-3642.2007.00269.x
- Peyer, Karin. “A reconsideration of Compsognathus from the Upper Tithonian of Canjuers, southeastern France.” Journal of Vertebrate Paleontology 26.4 (2006): 879-896. https://www.jstor.org/stable/4524640
- Wikipedia contributors. “Compsognathus.” Wikipedia, 17 Jun. 2024, https://en.wikipedia.org/wiki/Compsognathus
A note on the scales on the tail of Compsognathus: in the supporting information of “Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs” they say that the scales are “not integumentary in origin” I also wonder since the “scales” are found in the larger specimen from France while the smaller holotype is from Germany I wonder if there is a reanalysis in the future regarding validity of both specimens belong to the same genus or species (this is much more of wild speculation and both specimens belonging to the same genus/species still seems very much possible and is probably the case, just something to think about).