The large French Compsognathus specimen

Updated May 23, 2016 with a new mandible. M. Mortimer pointed out correctly that I had traced two coincident mandibles as one. 

The less well-known
French specimen of Compsognathus corallestris (Bidar et al. 1972b; Peyer 2006; CNJ79) is a bit larger with a different morphology (Fig. 1) than the coeval smaller Bavarian Solnhofen specimen, Compsognathus longipes (Fig. 1 right). Dr. Peyer considers these two Late Jurassic theropods conspecific and representative of ontogenic rather than phylogenetic variation.

Figure 1. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

Figure 1. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

From the Peyer abstract:
“The absence of an external mandibular fenestra, dorsally fan-shaped dorsal neural spines with hook-shaped ligament attachments, and a  very short McI and a PhI-1, which is stouter than the radius distinguish compsognathids from other coelurosaurs. Anatomical and morphological characters of the Bavarian specimen of Compsognathus are nearly identical to those of the French specimen. The differences are related to ontogenetic or within-species variation or are caused by preservational factors. Therefore this study proposes that C. corallestris is a subjective junior synonym of Compsognathus longipes from Bavaria.”

You’ll note that “compsognathids” sensu Peyer are scattered throughout this large reptile tree subset of the Theropoda (Fig. 2). Sinocalliopteryx and Juravenator are widely considered compsognathids, yet both nest far from one another here.

I tested the ontogenetic hypothesis of Peyer
in the large reptile tree. Indeed, the two Compsognathus specimens do nest next to one another, but at the bases of two different clades.

The smaller Compsognathus specimen
nested with Struthiomimus, Ornitholestes, Microraptor and T-rex, among others.

The large Compsognathus specimen
nested with the oviraptorid, Khaan, Limusaurus, therizinosaurs, Sinosauropteryx and others. More derived clades include Eotyrannosaurus and other paravians such as dromareosaurids, troodontids and birds.

Figure 2. Compsognathus corrallensis nests close to the holotype smaller specimen, but at the base of the next clade, which includes oviraptors, therizinosaurs, Juravenator and Sinosauropteryx.

Figure 2. Compsognathus corrallensis nests close to the holotype smaller specimen, but at the base of the next clade, which includes oviraptors, therizinosaurs, Juravenator and Sinosauropteryx. That means it is not the adult version of the smaller specimen.

The new reconstruction
of the large Compsognathus skull is relatively shorter. Both the premaxilla and the dentary tip are oriented slightly down. The bones of the mandible slid apart during taphonomy. Put them back together to match the skull length and you might get a mandibular fenestra, as also seen in the smaller Compsognathus. The new skull reconstruction (Fig. 1) was created using DGS, not freehand as in the Peyer reconstruction.

Figure 3. DGS tracing of large French Compsognathus skull. These parts were used to make the reconstruction in figure 1. Only the left side and top elements were colorized.

Figure 3. DGS tracing of large French Compsognathus skull. These parts were used to make the reconstruction in figure 1. Only the left side and top elements were colorized.

Current traditional compsognathids include the following taxa

  1. Compsognathus
  2. Sinocalliopteryx
  3. Juravenator (some say yes, others say no)
  4. Sinornithosaurus
  5. Huaxiagnathus

In the large reptile tree the clade that includes Compsognathus now include the following taxa

  1. Compsognathus
  2. all ornithomimids, including Struthiomimus

References
Bidar AL, Demay L and Thomel G 1972b. Compsognathus corallestris,
une nouvelle espèce de dinosaurien théropode du Portlandien de Canjuers (Sud-Est de la France). Annales du Muséum d’Histoire Naturelle de Nice 1:9-40.
Ostrom JH 1978. T
he osteology of Compsognathus longipes. Zitteliana 4: 73–118.
Peyer K 2006.
A reconsideration of Compsognathus from the upper Tithonian of Canjuers, southeastern France, Journal of Vertebrate Paleontology, 26:4, 879-896,
Wagner JA 1859. Über einige im lithographischen Schiefer neu aufgefundene Schildkröten und Saurier. Gelehrte Anzeigen der Bayerischen Akademie der Wissenschaften 49: 553.

wiki/Compsognathus

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4 thoughts on “The large French Compsognathus specimen

  1. I sent you Peyer’s paper, hoping it would help, but you didn’t actually use her info. Do you really think your tracings of a low res photo are better than someone’s detailed drawings who had the specimen’s redescription as their thesis? For instance, your dentary is actually both dentaries, with one in dorsal view. You can even see the alveoli lining the bottom edge of the dentary in your figure above. Or how your articular is a mismash of both articulars that projects ventrally like no other theropod. Thus your skull reconstruction doesn’t actually represent the fossil.

    • Thank you for pointing out that error. As I’ve said on many occasions, I make errors all the time and correct them when I find them or am alerted to them. Mickey, your tone has unnecessary venom attached. You’ll be a better scientist when you more professionally say, “the dentary you traced is actually both dentaries” and leave it at that. But I’ll take the venom if that gets the job done.

      • But _why_ do you make these errors when you have the paper right in front of you? Don’t you use the author’s illustrations to help you interpret the specimen? I could point out more errors in your reconstruction (e.g. your prefrontals are parts of the frontal, matrix and small fragments, while you made the actual prefrontal part of the frontal…), but the easier thing to say is- “Use Peyer’s illustration.” She got basically everything right.

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