As everyone knows, one Jurassic lizard, Bavarisaurus macrodactylus (Figs. 1-4, = Homoesaurus macrodactylus Wagner 1852, Hoffstetter 1964; length: ~20cm, (Lower Tithonian), Solnhofen), was found inside the belly of a small Jurassic dinosaur, Compsognathus (BSPHM AS-1-563). All curled up like the good meal it was, Bavarisaurus has been added to various lepidosaur phylogenetic analyses, but, to my knowledge, it has not been reconstructed in the literature. However, Tracy Ford did a good job here.
Not sure how much good this will do, but I took all the bones I could see and segregated from the dinosaur bones (Fig. 2), then rearranged them as well as I could (Fig. 3). Seems like Bavarisaurus had quite a long tail when it is all stretched out! Looking at the maxilla and mandible you’ll notice the teeth don’t match. Small triangle-shaped teeth are on the dentary, but posteriorly-oriented narrow, sharp teeth appear on the maxilla. The presumes that I have the maxilla correctly oriented.
The next step was to tentatively nest the elements phylogenetically, then clean them up in a better presentation in dorsal and lateral views (Fig. 4). A final scoring of elements nests Bavarisaurus more securely.
Bavarisaurus is another tritosaur.
And that’s why it nests uncertainly at the base of the Squamata in prior analyses that did not include any or many other tritosaurs — because it doesn’t nest in the Squamata. In the large reptile tree Bavarisaurus nests between Meyasaurus and the Dahugou lizard + Lacertulus, not far removed from Dalinghosaurus, which it resembles by convergence.
So based on the presence of Lacertulus in the Late Permian, something very much like Bavarisaurus originated in the Permian and continued to the Late Jurassic where we find the first and last of this genus inside the ribcage of Compsognathus.
Evans SE, Raia P and Barbera C 2004. New lizards and rhynchocephalians from the Lower Cretaceous of southern. Italy. Acta Palaeontologica Polonica 49:393–408.
Hoffstetter R 1964. Les Sauria du Jurassique supérieur et specialement les Gekkota de Baviére et de Mandchourie. Senckenberger Biologische 45, 281–324.
Nopcsa F 1903. Neues ueber Compsognathus. Neues Jahrbuch fur Mineralogie, Geologie und Palaeontologie 16: 476-494.
Wagner A 1852. Neu-aufgefundene Saurier, Uberreste aus dem lithographischen Schiefern und dem obern Jurakalke: Abhandlungen der Bayerischen Akademieder Wissenschaften Mathematisch-naturwissenschafliche Kl, 3(6): 661-710.