Friday, May 25, 2018

[Paleontology • 2018] Parahenodus atancensis • A New Placodont from the Upper Triassic of Spain provides New Insights on the Acquisition of the Specialized Skull of Henodontidae


Parahenodus atancensis
 de Miguel Chaves, Ortega & Pérez‐García, 2018

   DOI: 10.1002/spp2.1218 
Illustration: Eloy Manzanero  divulgauned.es

Abstract
Henodus chelyops Huene is considered to be a highly autapomorphic cyamodontoid placodont with specialized trophic adaptations relative to all the other members of Placodontia. It has been exclusively found in the Carnian (Upper Triassic) of Tübingen (Germany). Here we present a partial skull identified as a new cyamodontoid placodont from the Upper Triassic of El Atance (Guadalajara Province, Spain), Parahenodus atancensis gen. et sp. nov. It is recognized as the sister taxon of H. chelyops, both taxa composing the clade Henodontidae. An emended diagnosis for H. chelyops and Henodontidae is given here. Parahenodus atancensis shares with H. chelyops several cranial characters considered until now to be autapomorphic for the latter, but it also retains some states common in most cyamodontoids. Thus, the discovery of P. atancensis provides new information on the acquisition process of the highly specialized skull of the Henodontidae.

Key words: Placodontia, Cyamodontoidea, Henodontidae, Parahenodus atancensis, El Atance.


SYSTEMATIC PALAEONTOLOGY

SAUROPTERYGIA Owen, 1860
PLACODONTIFORMES Neenan et al., 2013
PLACODONTIA Cope, 1871
CYAMODONTOIDEA Nopcsa, 1923
CYAMODONTIDA Nopcsa, 1923
HENODONTIDAE Huene, 1936

Type species. Henodus chelyops Huene, 1936.

Included species. Henodus chelyops, Parahenodus atancensis gen. et sp. nov.


Emended diagnosis. Clade of Cyamodontida characterized by the following exclusive characters: flat skull; maxillae without tooth plates but with a deep ventral longitudinal groove; palatines with a single posterior tooth plate; upper temporal fenestrae reduced to absent; parietals broad and fan-shaped; presence of contact between the jugals and the squamosals; palatines separated from one another by long pterygoids; cephalic condyle of the quadrates posteriorly expanded and abutting a ventral flange of the squamosals.

Distribution. Upper Triassic (Carnian to Norian) of Europe (southern Germany and central Spain).

Genus HENODUS Huene, 1936 
Type species. Henodus chelyops Huene, 1936.

....




FIG. 1. Skull MUPA ATZ0104, holotype of the cyamodontoid placodont Parahenodus atancensis gen. et sp. nov., from the Upper Triassic of El Atance.
A, dorsal view. B, ventral view. C, schematic interpretation of the skull in dorsal view. D, schematic interpretation of the skull in ventral view.
Scale bars represent: 20 mm (A–D) 

Genus PARAHENODUS nov. 
Type species. Parahenodus atancensis sp. nov. 

Parahenodus atancensis sp. nov. 

Derivation of name. Para (paqa), Greek for ‘near’ or ‘beside’, implying morphological closeness to Henodus Huene, 1936; atance, from El Atance, the fossil site; and ensis, a Latin adjectival suffix meaning ‘pertaining to’.

FIG. 2. Strict consensus tree obtained from our phylogenetic analysis based on the cranial data matrix of Neenan et al. (2015) showing the position of the cyamodontoid placodont Parahenodus atancensis gen. et sp. nov., from the Upper Triassic of El Atance. Bootstrap frequencies that exceed 50% (top) and Bremer support values (bottom) are indicated.

  


Carlos de Miguel Chaves,  Francisco Ortega and Adán Pérez‐García. 2018. A New Placodont from the Upper Triassic of Spain provides New Insights on the Acquisition of the Specialized Skull of Henodontidae.  Papers in Palaeontology.  DOI: 10.1002/spp2.1218

Describen una nueva especie de placodonto que habitó en Guadalajara durante el Triásico Superior  divulgauned.es/placodonto/ via @divulgauned


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