Occurrence of Torvoneustes (Crocodylomorpha, Metriorhynchidae) in marine Jurassic deposits of Oaxaca, Mexico

Abstract

-IGM 9026 is a singular fossil collected at the beginning of the 20th century in an improperly documented site within the Tlaxiaco Basin, near to Tlaxiaco town, Oaxaca, Mexico. The age of the site was suggested as being early Cretaceous. This specimen is the holotype of Plesiosaurus (Polypticodon) mexicanus, which later was identified as a possible late Jurassic marine crocodylomorph of the family Metriorhynchidae, and consequently it was referred as ?Cricosaurus mexicanus. The present study provides a re-description of this fossil based on a microscopic analysis and the use of white and UV lights; these analyses led to the discovery of peculiar dental characters diagnostic of the genus Torvoneustes. This finding supports the re-classification of IGM 9026 under a new nominal combination as Torvoneustes mexicanus. Along the Tlaxiaco Basin, the fossil preservation mode and lithological composition observed in IGM 9026 only occur in the marine vertebrates recently discovered in Yosobé, a Kimmeridgian shale outcrop characterized by clay calcareous nodules that belong to the Sabinal Formation, near Tlaxiaco town. This peculiarity suggests that T. mexicanus could represent an additional element of the Kimmeridgian vertebrate assemblage recovered in this geological unit. The two nominal species of Torvoneustes were collected in Kimmeridgian marine deposits of England; hence, this finding expands the geographical distribution of Torvoneustes all along the Tethys Sea, from its Eastern/European to western/ Caribbean domains. Keywords:Torvoneustes, Plesiosaurus mexicanus, hispanic corridor, Kimmeridgian, Tlaxiaco Basin, Sabinal Formation. RESUMO -O exemplar IGM 9026 é um fóssil singular coletado no princípio do século 20 em um sítio pouco conhecido da Bacia Tlaxiaco, situado próximo a cidade de Tlaxiaco, Estado de Oaxaca, sul do México, cuja idade foi vagamente sugerida como do Eocretáceo. Originalmente, este único exemplar é holótipo do plesiossauro Plesiosaurus (Polypticodon) mexicanus. Mais tarde, ele foi identificado como um possível crocodilomorfo marinho do Jurássico Superior da família Metriorhynchidae, e portanto, foi referido como ?Cricosaurus mexicanus. O presente estudo proporciona uma nova descrição deste fóssil baseado em uma análise microscópica, uso de luzes brancas e UV, que levou à descoberta de caracteres dentários únicos neste exemplar, que coincidem com aqueles do gênero Torvoneustes. Este achado apoia a reclassificação de IGM 9026 a partir de uma nova combinação nominal como Torvoneustes mexicanus. Ao longo da Bacia de Tlaxiaco, o modo de conservação dos fósseis e a composição litológica observada em IGM 9026 somente se repetem nos vertebrados marinhos da Formação Sabinal, recentemente descobertos nas proximidades de Tlaxiaco. Esta peculiaridade sugere que T. mexicanus poderia representar um elemento adicional da associação de vertebrados fósseis do Kimmeridgiano da dita unidade geológica. As duas espécies nominais de Torvoneustes foram coletadas em jazimentos Kimeridgianos da Inglaterra, de f...

Evidence of thalattosuchian crocodylomorphs in the Portland Stone Formation (Late Jurassic) of England, and a discussion on Cretaceous teleosauroids

“…The isolated tooth crown described herein has a suite of morphological characteristics that are only known in two genera of thalattosuchians, the teleosauroid Machimosaurus and the metriorhynchid Torvoneustes (von Meyer 1837; Krebs 1967;Hua 1999;Lepage et al 2008;Andrade et al 2010;Barrientos-Lara et al 2016;Young et al 2013Young et al , 2014aYoung et al , 2014b):…”

Cranial and endocranial anatomy of a three‐dimensionally preserved teleosauroid thalattosuchian skull

“…However, it received less study during the latter part of the 20th century (but see Westphal, 1961, 1962; Buffetaut, 1980, 1982; Vignaud, 1995, Hua & de Buffrenil, 1996; Hua & Buffetaut, 1997). A renaissance of thalattosuchian research began in the early 21st century (e.g., Aiglstorfer, Havlik, & Herrera, 2020; Barrientos‐Lara, Alvarado‐Ortega, & Fernández, 2018; Barrientos‐Lara, Herrera, Fernández, & Alvarado‐Ortega, 2016; Buchy, Vignaud, Frey, Stinnesbeck, & Gonzalez Gonzalez, 2006; Buchy, Young, & Andrade, 2013; Cau & Fanti, 2011; Fernández & Gasparini, 2000, 2008; Fernández & Herrera, 2009; Foffa & Young, 2014; Gasparini, Cichowolski, & Lazo, 2005; Gasparini, Pol, & Spalletti, 2006; Gasparini, Vignaud, & Chong, 2000; Herrera et al, 2009, 2013a,b,c, 2015, 2017; Hua, 2020; Hua, Vignaud, Atrops, & Clément, 2000; Leardi, Pol, & Fernández, 2012; Mueller‐Töwe, 2006; Ösi, Young, Galácz, & Rabi, 2018; Parrilla‐Bel, Young, Moreno‐Azanza, & Canudo, 2013; Pierce, Angielczyk, & Rayfield, 2009a, 2009b; Pierce & Benton, 2006; Pierce, Williams, & Benson, 2017; Pol & Gasparini, 2009; Wilberg, 2015a, 2015b; Young et al, 2010, 2012; Young & Andrade, 2009; Young, Andrade, Cornée, Steel, & Foffa, 2014; Young, Andrade, Etches, & Beatty, 2013; Young, Bell, Andrade, & Brusatte, 2011), with a recent focus on the anatomy, taxonomy, and phylogenetic relationships of teleosauroids (Brusatte et al, 2016; Foffa, Johnson, Young, Steel, & Brusatte, 2019; Herrera, Leardi, & Fernandez, 2018; Johnson et al, 2017,…”

“…However, it received less study during the latter part of the 20th century (but see Westphal, 1961Westphal, , 1962Buffetaut, 1980Buffetaut, , 1982Vignaud, 1995, Hua & de Buffrenil, 1996Hua & Buffetaut, 1997). A renaissance of thalattosuchian research began in the early 21st century (e.g., Aiglstorfer, Havlik, & Herrera, 2020;Barrientos-Lara, Alvarado-Ortega, & Fern andez, 2018;Barrientos-Lara, Herrera, Fern andez, & Alvarado-Ortega, 2016;Buchy, Vignaud, Frey, Stinnesbeck, & Gonzalez Gonzalez, 2006;Buchy, Young, & Andrade, 2013;Cau & Fanti, 2011;Fern andez & Gasparini, 2000Gasparini, Cichowolski, & Lazo, 2005;Gasparini, Pol, & Spalletti, 2006;Gasparini, Vignaud, & Chong, 2000;Herrera et al, 2009Herrera et al, , 2013aHerrera et al, ,b,c, 2015Herrera et al, , 2017Hua, 2020;Hua, Vignaud, Atrops, & Clément, 2000;Leardi, Pol, & Fern andez, 2012;Mueller-Töwe, 2006;Ösi, Young, Gal acz, & Rabi, 2018;Parrilla-Bel, Young, Moreno-Azanza, & Canudo, 2013;Pierce, Angielczyk, & Rayfield, 2009a, 2009bPierce & Benton, 2006;Pierce, Williams, & Benson, 2017;Pol & Gasparini, 2009;Wilberg, 2015aWilberg, , 2015b…”