First report of a derived abelisaurid theropod from the Bajo de la Carpa Formation (Late Cretaceous), Patagonia, Argentina

Abstract

An isolated anterior caudal vertebra of a medium-large sized theropod dinosaur is reported here. It comes from the Bajo de la Carpa Formation (Santonian, Late Cretaceous), Río Colorado Subgroup, Río Negro Province, northern Patagonia, Argentina. The specimen, MACN-PV-RN 1012, exhibits several derived characters that are diagnostic among theropods. Specifically, MACN-PV-RN 1012 is referable to Abelisauroidea because it possesses a centrodiapophyseal lamina on the ventral surface of the transverse processes, and to Abelisauridae due to the presence of transverse processes that are 1.4 times longer than the anteroposterior length of the centrum, a large median depression anterior to the base of the neural spine, and the lack of a prespinal fossa. MACN-PV-RN 1012 is included within Carnotaurinae, sharing with <i>Carnotaurus </i>and <i>Aucasaurus </i>transverse processes that are oriented dorsolaterally at an angle of 45° or more with regard to the horizontal axis of the vertebra. Thus, the specimen described here constitutes the first record of a derived abelisaurid from the Bajo de la Carpa Formation

Predation Bite-Marks on a Peirosaurid Crocodyliform from the Upper Cretaceous of Neuquén Province, Argentina

“…This observation points further towards the possibility that a large theropod dinosaur was responsible for the bite marks in MUCPv-27. As previously mentioned, several carnivorous dinosaurs are known from the Bajo de la Carpa Formation, although only some of them had large skulls, namely abelisaurids and carcharodontosaurids (Porfiri and Calvo, 2006;Coria and Arcucci, 2004;Porfiri et al, 2008;Ezcurra and Méndez, 2009). The predator that caused the bites did not swallow the tail section after the attack, possibly because of the difficulty of tearing apart and swallowing this armored body part.…”

“…The theropod dinosaur fauna is also diverse, including the small abelisauroid theropod Velocisaurus unicus Bonaparte, 1991, found in Neuquén (also in the Campus of the University of Comahue). Recently, the presence of carnotaurine abelisaurid theropods was reported from the top of the unit in the La Invernada region , in northern Neuquén (Porfiri and Calvo, 2006), and also at Paso Córdova (Río Negro Province) (Ezcurra and Méndez, 2009). Aditionaly, remains of indeterminate theropods coming from the Auca Mahuida region (Neuquén Province) were considered by Coria and Arcucci (2004) to be large basal tetanurans related to carcharodontosaurids.…”

A New Furileusaurian Abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), Northern Patagonia, Argentina

“…Regarding dinosaurs, the record from this unit is profuse. In its deposits, many taxa were found: the titanosaurian sauropods Bonitasaura salgadoi, Traukutitan eocaudata, Overosaurus paradasorum, and Rinconsaurus caudamirus (Apesteguía, 2004;Juárez Valieri and Calvo, 2011;Coria et al, 2013;Filippi, 2015); ornithopods, such as the elasmarian Mahuidacursor lipanglef and indeterminate forms (Cruzado-Caballero et al, 2018; and theropods, such as the noasaurids Velocisaurus unicus (Bonaparte, 1991), abelisaurids (Ezcurra and Méndez, 2009), the megaraptorid tetanuran Tratayenia rosalesi (Porfiri et al, 2018), the alvarezsaurids Alvarezsaurus calvoi and Achillesaurus manazonnei (Bonaparte, 1991;Martinelli and Vera, 2007), and the avialans Patagopteryx deferrariisi and Neuquenornis volans (Alvarenga and Bonaparte, 1992;Chiappe and Calvo, 1994). It should be noted that all these taxa come from different localities and different levels in the Bajo de la Carpa Formation.…”

Unexpected new lizard from the Late Cretaceous of southern South America sheds light on Gondwanan squamate diversity

“…The mesoeucrocodylian Cynodontosuchus rothi might have been found at this locality (Woodward, 1896), but a precise location is unknown. A caudal vertebra of a medium-sized indeterminate abelisaurid (Ezcurra & Méndez, 2009) was reported as possibly recovered at the "Paso Córdoba" locality. This specimen aside, the faunal content of the "Boca del Sapo" and "Paso Córdoba" localities is almost entirely composed of small-sized animals.…”