Wednesday, December 10, 2014

[Paleontology • 2014] Titanochelon • New Generic proposal for the European Neogene Large Testudinids (Cryptodira) and the First Phylogenetic Hypothesis for the medium and large representatives of the European Cenozoic record

Titanochelon bolivari  (Hernández-Pacheco, 1917)
Titanochelon, a new genus of giant tortoise that lived in Europe and western Asia between 20m and 2m years ago. 
Illustration: Mauricio Antón | DOI: 10.1111/zoj.12183

Fossil testudinids are known in Europe since the Eocene, with several taxa of medium size (from more than 0.3 m to less than 0.7 m) recognized in the Palaeogene record, most of them being poorly known. The size of several European Neogene taxa was larger (between 1 and 2 m). These large testudinids were relatively abundant and diverse, ranging from the early Miocene to the Pleistocene. However, there is a nomenclatural gap at the generic level for the Neogene forms, as their generally used assignment to the more primitive Eocene Cheirogaster cannot be sustained. This is because relatively little material has been assigned to the described species, and also because of the absence of a detailed study comparing all of the European taxa. Here, the European Cenozoic taxa are incorporated for the first time in a data matrix, so that a hypothesis on their phylogenetic relationships is justified. This study identified the large testudinids from the Neogene of Europe as belonging to a monophyletic clade, assigned to the new genus Titanochelon. The hitherto poorly understood ‘Testudobolivari, proposed nearly a century ago but lacking diagnosis, is analysed in detail. It is recognized as the best-represented large testudinid from the European record, and is identified as the type species of Titanochelon gen. nov. Its comparison with the other Neogene species allowed a detailed study of the new genus and an analysis of its phylogenetic relationships with the other European taxa.

Keywords: Cheirogaster; Europe; Palaeogene; phylogenetic relationships; Testudinidae; ‘Testudo’ bolivariTitanochelon gen. nov.

giant tortoise Titanochelon bolivari
1) reconstruction by paleoartist Mauricio Antón; 2) - 7) fossil of Titanochelon
| Source: MNCN et culturacientifica

Figure 2. Historical photographs of the shell of the lectotype of Titanochelon bolivari (‘Alcalá 2’), from the MN6 zone (late Aragonian, middle Miocene) of Cerro del Viso, in Alcalá de Henares (Madrid, Spain). Specimen collected in 1917.
A, right lateral view. Modified version of ACN 6553, photograph corresponding to plate XXXIV in Royo y Gómez (1928b). B, left lateral view. Modified version of the unpublished photograph ACN 6554. C, anteroventral view. Modified version of the unpublished photograph ACN 6555. D, dorsoposterior view. Modified version of ACN 6556, photograph corresponding to plate XXXV in Royo y Gómez (1928b).
Original photographs taken by Eduardo Hernández-Pacheco.


Type species: Titanochelon bolivari (Hernández-Pacheco, 1917a)

Included species: Titanochelon bolivari comb. nov., Titanochelon eurysternum (Gervais, 1848–1852) comb. nov., Titanochelon ginsburgi (de Broin, 1977) comb. nov., Titanochelon vitodurana (Biedermann, 1862) comb. nov., Titanochelon steinbacheri (Karl, 1996) comb. nov., Titanochelon leberonensis (Depéret, 1890) comb. nov., Titanochelon schafferi (Szalai, 1931) comb. nov., Titanochelon perpiniana (Depéret, 1885) comb. nov., Titanochelon bacharidisi (Vlachos et al., 2014) comb. nov. 
Probably included species: cf. Titanochelon gymnesicus (Bate, 1914) comb. nov

Adán Pérez-García and Evangelos Vlachos. 2014. New Generic proposal for the European Neogene Large Testudinids (Cryptodira) and the First Phylogenetic Hypothesis for the medium and large representatives of the European Cenozoic record. Zoological Journal of the Linnean Society. 172, 653–719. DOI: 10.1111/zoj.12183

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