Procompsognathus

Credit: Gabriel Ugueto.

*Procompsognathus* is an extinct genus of theropod dinosaur that lived in Germany during the Late Triassic.

## History

*Procompsognathus* means 'before' and *Compsognathus*, 'elegant jaw'. The species epithet, '*triassicus*' refers to the Triassic period, where *Procompsognathus* lived.

## Description

*Procompsognathus* is known from several specimens. One of which, the holotype, consists of three blocks of sandstone. One of which preserves a 7 centimeter long, crushed, slim head and mandible. The other two, incomplete postcranial remains, including twenty nine vertebrae in total, ribs, a fragmented forelimb, the shoulder girdle, a pair of pubis, an ilium and both hindlimbs. This specimen represents an adult individual. *Procompsognathus* was originally classified a proto-bird, but was later moved to Coelophysidae. Material attributed to *Procompsognathus* also includes an isolated hand in one specimen and a fragmentary skull and mandible in the other. *Procompsognathus* prowled around on two legs, had slender hind legs, short arms bearing long clawed hands, an elongated snout packed with many small teeth and a stiff tail. The type femur measures about 93 millimeters long and the tibia measuring about 112 millimeters long. The tibia is roughly 20% longer than the femur occurring in *Procompsognathus*. This means that *Procompsognathus* had an adaptation for strongly correlated and developed hind limbs, which were able to run long distances at a good pace in its paleoecosystem.

In 1998, Chatterjee noted all the following features to be original to *Procompsognathus*. They included: an accessory to the maxillary fenestra, the vomers fuse, elongating towards the choana, a quadrate head receives the squamosal without paroccipital contact, the lateroshenoid has a transversal postorbital process and the orbitosphenoids fuse. It is also noted that Procompsognathus has a more slender scapula than *Coelophysis bauri*. The fragmentary nature of the holotype and attributed specimens makes study difficult. Some scientists interpret the holotype as non-dinosaurian, as a sort of Pseudosuchia. Another author attributes the remains as a chimera of *Segisaurus*, *Saltoposuchus*, with remains later attributed to *Syntarsus* and Coelophysidae indet.. With phylogenic analysis, it was determined the remains belonged to a single animal, sitting inside Coelophysidae. Other attributed material was also determined crocodylomorph and Tetanurae, basal archosaur, ornithodiran and ceratosaur remains. The most current research considers *Procompsognathus* to be a basal, non-dinosaurian ornithodiran. Further study must be conducted.

## Paleoecology

*Procompsognathus* lived in a semi-dry inland ecosystem, hunting small lizards, insects and small prey items. *Procompsognathus* lived alongside coelophysids *Halticosaurus* and *Dolichosuchus*, plateosaurs *Plateosaurus* and *Efraasia* alongside an unnamed herrerasaur ichnogenus.

## Notable Specimens

* SMNS 12591: The holotype, consisting of three slabs of sandstone, with crushed skull and postcranial remains. These remains may have belonged to several different animals.
* SMNS 12352: Attributed remains, may belong to another animal.
* SMNS 12352a: Attributed remains, may belong to another animal.

## References

https://en.wikipedia.org/wiki/Procompsognathus