Falseryx, SZYNDLAR & RAGE, 2003

Szyndlar, Zbigniew, Smith, Richard & Rage, Jean-Claude, 2008, A new dwarf boa (Serpentes, Booidea, ‘ Tropidophiidae’) from the Early Oligocene of Belgium: a case of the isolation of Western European snake faunas, Zoological Journal of the Linnean Society 152 (2), pp. 393-406 : 394-395

FALSERYX SZYNDLAR & RAGE, 2003

Type species: Falseryx petersbuchi Szyndlar & Rage, 2003 .

Emended diagnosis of the genus (modified from Szyndlar & Rage, 2003): A small member of the ‘Tropidophiidae’. Known from vertebrae coming from all major portions of the column. Dimensions of trunk vertebrae do not change significantly, regardless of their position in the trunk portion of the column. Dimensions of caudal vertebrae diminish toward the end of the tail.

Vertebrae from the middle trunk portion of the column are somewhat longer than high in lateral view. The interzygapophyseal constriction is moderately well marked. The neural arch is strongly depressed. The posterior border of the neural arch is moderately to weakly notched. The neural spine is very low; it occupies usually one-third of the neural arch length and it reaches the posterior border of the neural arch; the spine is often thickened dorsally. The centrum is longer than wide. The haemal keel is broad, widening and becoming flattened posteriorly; in lateral view, the ventral margin of the keel is straight. The zygosphene is straight or slightly concave in anterior view and three-lobed or two-lobed (with central lobe absent or reduced) in dorsal view. The prezygapophyses are located clearly above the floor of the neural canal and are weakly inclined. The prezygapophyseal processes are acute and short (but clearly seen in dorsal view). The prezygapophyseal articular facets are relatively large; their long axis is clearly oblique in dorsal view. The prezygapophyseal buttresses are expanded anteriorly into moderately to strongly developed tubercles. The paradiapophyses are stout, higher than long, weakly divided into para- and diapophyseal portions; they do not project downwards beyond the cotyle lip. The cotyle is circular. The paracotylar foramina are absent.

Posteriormost trunk, cloacal and anterior caudal vertebrae bear a short hypapophysis instead of haemapophyses. Middle caudal vertebrae bear haemapophyses, reduced to a haemal keel in posterior caudal vertebrae.

Differential diagnosis: Differs from the remaining Booidea (except for the Erycinae , Ungaliophis , Dunnophis , Messelophis and Rottophis ) by having neural spine distinctly restricted posteriorly. Differs from the Erycinae by not having complex caudal vertebrae and by having hypapophysis in anterior caudal vertebrae. Differs from Ungaliophis by having caudal vertebrae provided with hypapophyses and haemapophyses. Differs from all snakes except for the Tropidophiinae (and perhaps Rottophis ) by having caudal portion of the vertebral column provided with hypapophysis in anterior caudals, haemapophyses in middle caudals and haemal keel in posterior caudals. Differs from Rottophis , Platyspondylia and Messelophis by having larger and more heavily built trunk vertebrae. Differs from Platyspondylia by having distinct prezygapophyseal processes.

For differences in vertebral morphology between Falseryx and several North American fossil booids (in some aspects resembling Falseryx ) see Szyndlar & Rage (2003).