More than one? the hidden diversity of the limbed snakes of La Buitrera (Candeleros Formation, early Late Cretaceous) Argentina

GARBEROGLIO, FERNANDO F.; CALDWELL, MICHAEL W.; APESTEGUÍA, SEBASTIÁN; RANDALL NYDAM

Salt Lake City

Congreso; Society of Vertebrate Paleontology 76th annual meeting; 2016

Society of Vertebrate Paleontology

Najash rionegrina, the only limbed snake described from La Buitrera, aorthemPagonia ArgtntUi.a , provides rare insights on the anatomy of Cretac:eous snake evolutioo in soutbero contintnts. It also addresses a number of impo11ant cha.racters and character states that havt traditlonatly beeu considered key synRpopm.ot´bits in supporting variou.s phylogenetic scheu1es for suakesand their kin. N. rfonegrfna VAS diagnosed from au a11iculnted postcranial skeleton with rear limb.s, and a.ssocinted c1·anla.l ffagu1ents. Subsequeut fieldwork has produced six ue.v.? skulls (7 total). so11le a$sociated Vith postcrania, from a series of locolities widely separated (up 10 30 l:m), aud aloag a stratigraphic iaterva l through the last 70 m of the Candeleros Formation. The sl-ulls and postcrania share a co1IUJ1oa general morphology; s -ull leagths range from small (-2cm) to large (-6-8 cm) and may well represen!an ontogenetic seri..withia the same sp&ies. Altematively. the range of sl´llll sizes, Vhen linked to variatioo in postcranial anatomy (e.g., overally´-enebral morphology, presettce or abseoce of hypapophyseal L-,,elslbaemall:eels, height of aeutal spiaes, etc.). also suggests that s -uU aad postcraaial -ariation might be plained by the presence of multiple specie> in the -u. BuitreraPaleoatological Area Assemblage" (LBPA). In short, the "LBPA Assemblage" is not necessarily an assemblage from a single population preserving juveniles and adults of a single species. bw may bt sugg.e!.1ive of a cluster of clostly rela1ed species. These species, form.ing tbe "Naja.sh-as-semblage", share numerous featutt.s of tht s.l and skeleton in conunoo Vitb the younger "´Dinilysia-assemblage ´" (Rio Colorado Formation. Argeatina). These data suppott the presence of a Gondwaaan lineage of closely related snakes.