New record of a Mesozoic gondwanatherian mammaliaform from Southern Patagonia
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ORIGINAL PAPER
New record of a Mesozoic gondwanatherian mammaliaform from Southern Patagonia Nicolás R. Chimento 1
&
Federico L. Agnolin 1,2 & Takanobu Tsuihiji 3 & Makoto Manabe 3 & Fernando E. Novas 1
Received: 11 April 2020 / Revised: 13 August 2020 / Accepted: 28 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Gondwanatheria is an enigmatic mammaliaform clade distributed in the Cretaceous and Paleogene of South America, Africa, Madagascar, India and Antarctica. The Mesozoic record in South America is restricted to the Latest Cretaceous of Río Negro and Chubut provinces, Argentina and Magallanes Region of southern Chile. The aim of the present contribution is to describe a new specimen of gondwanatherian mammaliaforms from beds belonging to the Maastrichtian Chorrillo Formation, cropping out 30 km SW of El Calafate, Santa Cruz Province, Argentina. It is represented by a single molariform referable to the species Magallanodon baikashkenke with which it shares a unique combination of characters. Analysis of the unique combination of characters exhibited by Magallanodon shed doubts on the monophyly of Ferugliotheriidae and suggest that South American taxa may be closely related to each other. The wide geographical distribution and occurrence of gondwanatherians on geological units of diverse origins suggest that they were capable of facing disparate environmental conditions. Keywords Gondwanatheria . Late Cretaceous . Santa Cruz province . Argentina
Introduction Gondwanatheria is one of the most enigmatic Late Mesozoic mammaliaform clades, whose phylogenetic relationships remain disputed. Gondwanatherians are mostly documented on isolated teeth and partial jaws, and just two taxa are represented by fairly complete remains (Krause et al. 2014, 2020). Gondwanatherians are characterized by their rodent-like, enlarged, open-rooted incisors, as well as multicusped molariform cheekteeth (Krause and Bonaparte 1993). Their
Communicated by: Aurora Grandal-d'Anglade * Nicolás R. Chimento [email protected] 1
Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” - CONICET, Av. Ángel Gallardo 470, Buenos Aires 1405DJR, Argentina
2
Fundación de Historia Natural “Félix de Azara”, Departamento de Ciencias Naturales y Antropología, Universidad Maimónides, Hidalgo 775, 1405BDB Buenos Aires, Argentina
3
National Museum of Nature & Science, 4-1-1 Amakubo, Tsukuba 305-0005, Japan
remains have been collected from Late Cretaceous beds of Argentina, India, Tanzania and Madagascar, as well as from the Paleogene of Argentina and the Antarctic Peninsula (Bonaparte et al. 1993; Krause and Bonaparte 1993; Goin et al. 2004, 2006, 2012, 2020; Gurovich 2005, 2008; Krause 2013; Krause et al. 1997, 2014, 2020; Wilson et al. 2007; Prasad et al. 2007; Rougier et al. 2009; Gurovich and Beck 2009; Verma et al. 2012; Chimento et al. 2015; O’Connor et al. 2019). Currently recorded gondwanatherian genera are sorted into two main
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