Wednesday, July 8, 2015

[Paleontology • 2015] Babibasiliscus alxi • A New Eocene Casquehead Lizard (Reptilia, Corytophanidae) from North America


Babibasiliscus alxi  Conrad, 2015

Abstract

A new fossil showing affinities with extant Laemanctus offers the first clear evidence for a casquehead lizard (Corytophanidae) from the Eocene of North America. Along with Geiseltaliellus from roughly coeval rocks in central Europe, the new find further documents the tropical fauna present during greenhouse conditions in the northern mid-latitudes approximately 50 million years ago (Ma). Modern Corytophanidae is a neotropical clade of iguanian lizards ranging from southern Mexico to northern South America.


Fig 1. Holotype (UWBM 89090) specimen for Babibasiliscus alxi nov. taxon.
Photographs in (A) right lateral, (B) dorsal, and (C) ventral views. Digital reconstructions derived from HRXCT in (D) left lateral view and (E) transverse section. The vertical red line in (D) indicates the plane of section in (E).

Systematic paleontology

Squamata Oppel 
Iguania Cuvier 

Corytophanidae

Babibasiliscus gen. nov.
urn:lsid:zoobank.org:act:CB390F92-FDDC-4​CD8-B6A5-4E4C12836686

Babibasiliscus alxi, gen. et sp. nov.
urn:lsid:zoobank.org:act:F9FB7055-76FE-4​BBB-8DD6-7B795B01BB41

Holotype: UWBM 89090; a nearly complete skull with lower jaws and parts of first two cervical vertebrae (Fig 1).

Etymology: Babi- (Shoshoni) meaning “older male cousin” and Basiliscus, a corytophanid lizard. The generic name is meant to honor the Shoshone people who originally inhabited the areas in which the specimen was discovered and to refer to the relationship of the lizard with corytophanid lizards. At the request of Christian A Sidor, the species name honors John P. Alexander, who discovered the holotype.

Locality and Age: Lucky Lizard Locality (UWBM C1046), Uinta County, Wyoming. Blacks Fork Member of Bridger Formation (Bridger B), Green River Basin, late Early Eocene, approximately 48 Ma.

Fig 5. Photographs (A-C) and line drawings (D-F) of the skulls of selected corytophanid species in left lateral view.
 (A) Corytophanes cristatus (AMNH R 16390), (B) Laemanctus serratus (photograph; AMNH R 44982), (C) Basiliscus vittatus (AMNH R 147832), (D) Laemanctus serratus (line drawing), (E) Geiseltaliellus maarius, and (F) Babibasiliscus alxi taxon nov. (UWBM 89090). Note that it is unclear whether Babibasiliscus alxi taxon nov. had a parietal crest. Reconstructed areas are represented as semi-opaque areas and/or dotted lines.
Scale bars equal 10 mm. || doi: 10.1371/journal.pone.0127900

Fig 7. Phylogeny of corytophanids and distribution of anoles, para-anoles, corytophanids, and some malarial infection. (A) Time-calibrated phylogeny of the corytophanid genera with representative illustrations of their skull morphologies.

Jack L. Conrad. 2015. A New Eocene Casquehead Lizard (Reptilia, Corytophanidae) from North America. PLoS ONE. DOI: 10.1371/journal.pone.0127900


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