This article was downloaded by:[Columbia University] On: 17 September 2007 Access Details: [subscription number 769970891] Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Historical Biology An International Journal of Paleobiology Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713717695 Osteology and phylogeny of a new species of Araripesuchus (Crocodyliformes: Mesoeucrocodylia) from the Late Cretaceous of Madagascar Alan H. Turner a a Department of Geoscience, University of Iowa, Iowa City, IA, USA Online Publication Date: 01 January 2006 To cite this Article: Turner, Alan H. (2006) 'Osteology and phylogeny of a new species of Araripesuchus (Crocodyliformes: Mesoeucrocodylia) from the Late Cretaceous of Madagascar', Historical Biology, 18:3, 255 - 369 To link to this article: DOI: 10.1080/08912960500516112 URL: http://dx.doi.org/10.1080/08912960500516112 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Historical Biology, 2006; 18(3): 255–369 Osteology and phylogeny of a new species of Araripesuchus (Crocodyliformes: Mesoeucrocodylia) from the Late Cretaceous of Madagascar ALAN H. TURNER Department of Geoscience, University of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242, USA Abstract A new species of Araripesuchus present in the Maevarano Formation of Madagascar is described. The taxon is known from at least five individuals, including a nearly complete animal, three partial skulls and associated post-cranial remains, as well as disarticulated post-cranial elements. This large sample, coupled with CT-scans, allows a detailed description of its morphology. The new form shares a number of derived characters with Araripesuchus gomesii and Araripesuchus patagonicus, but is distinguished from them by the presence of four autapomorphies. Additionally, the new form lacks a number of derived features present in A. gomesii and A. patagonicus. Phylogenetic relationships of Araripesuchus are evaluated using a parsimony analysis including 29 mesoeucrocodylian taxa. In all of the most parsimonious trees the new taxon is recovered as sister group to A. gomesii þ A. patagonicus. Araripesuchus is Downloaded By: [Columbia University] At: 05:34 17 September 2007 diagnosed by five unambiguous synapomorphies and forms a clade with the Malagasy crocodyliform Mahajangasuchus insignis and peirosaurids. This group is depicted as more closely related to neosuchians than to notosuchians. When Araripesuchus wegeneri is included in the analysis, it is recovered as a member of the Araripesuchus clade. Although, its position in the clade is unresolved and character support is weak, this finding supports A. wegeneri as a valid species of Araripesuchus. Keywords: Crocodyliformes, osteology, Araripesuchus, Late Cretaceous, Madagascar, Maevarano formation Institutional Abbreviations: AMNH, American Museum of Natural History, New York; FMNH, Field Museum of Natural History, Chicago; GDM-DNPM, Divisao de Mineralogia e Geologia do Departmento Nacional da Produc¸ao Mineral, Rio de Janeiro, Brazil; GSP-UM, Geological Survey of Pakistan-University of Michigan collection, Quetta; IVPP, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, People’s Republic of China; MACN RN, Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina. Rio Negro Collection; MNN, Muse´e National de Niger, Niamey, Republic of Niger; MUC PV, Museo de Geologı´a y Paleontologı´a de la Universidad Nacional del Comahue, Neuque´n, Argentina; TMM, Texas Memorial Museum, Austin; UA, University of Antananarivo, Madagascar Introduction 1997, Asher and Krause 1998, Gottfried et al. 1998, Sampson et al. 1998, Buckley and Brochu 1999, Ongoing fieldwork in the Mahajanga Basin of Buckley et al. 2000, 2003, Forster and O’Connor northwestern Madagascar is expanding our 2000, Carrano et al. 2002, Whatley and Buckley knowledge of an unusual Late Cretaceous 2004). To this point, the described dinosaurian Gondwanan fauna. Part of this work has focused component is entirely saurischian, including on the Campanian to Maastrichtian age Maevarano armored sauropods, abelisaurid theropods, and Formation, which preserves a terrestrial and fresh- several birds (Forster et al. 1996, 1998, Sampson water assemblage including fish, amphibians, snakes, et al. 1998, 2001, Forster and O’Connor 2000, crocodyliforms, mammals, and dinosaurs (Krause Carrano et al. 2002, Curry-Rogers 2002, Curry- and Grine 1996, Forster et al. 1996, Krause et al. Rogers and Forster 2004). Correspondence: A. H. Turner, Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA. E-mail: [email protected] ISSN 0891-2963 print/ISSN 1029-2381 online q 2006 Taylor & Francis DOI: 10.1080/08912960500516112 256 A. H. Turner Figure 1. DGM-DNPM 432-R, Araripesuchus gomesii. Line interpretation of cranial sutures. A, Dorsal view. B, Ventral view. The crocodyliform component is extremely diverse, (Michard et al. 1990, Kellner 1994, Ortega et al. Downloaded By: [Columbia University] At: 05:34 17 September 2007 including at least seven separate taxa (Buckley et al. 2000, Prasad and Lapparent de Broin 2002). The 1997). These include large taxa, such as Tremato- contaxonomic status of Araripesuchus wegeneri, champsa (Buffetaut and Taquet 1979, Rasmusson described by Buffetaut (1981), with the South 2002) and Mahajangasuchus insignis (Buckley and American species of Araripesuchus has been ques- Brochu 1999, 2001), a long-snouted form (Buckley tioned. These hypotheses, however, were not tested et al. 2003), as well as smaller forms such as phylogenetically. This study will test this hypothesis by Simosuchus clarki (Buckley et al. 2000). Also recovered including A. wegeneri in the phylogenetic analysis with from these beds are crocodyliform remains that show other Araripesuchus species and a broad sample of a suite of derived features present in the small- mesoeucrocodylian taxa. bodied taxon Araripesuchus. This material has been referenced by previous authors (Buckley et al. 1997, Araripesuchus systematics and review of membership Buckley and Brochu 1999) and is described here as it This section is not intended to provide a thorough represents a new species of Araripesuchus.This redescription of each of these taxa. Rather, it discusses conclusion is based on a number of autapomorphic and comments on the other species referred to characteristics as well as the retention of some Araripesuchus and reviews our understanding of these plesiomorphic traits not exhibited in the South members of the taxon. American taxa, Araripesuchus gomesii, Araripesuchus patagonicus and Araripesuchus buitreraensis (Pol and Araripesuchus gomesii Price 1959 Apesteguı´a 2005). Since the taxon was first described, Araripesuchus The holotype of A. gomesii (DGM-DNPM 432-R; has been placed within, or sister to, a number of Figure 1) from the Early Cretaceous (Albian) Santana mesoeucrocodylian groups (Price 1959, Gasparini Formation of Brazil was initially described by Price 1971, Gasparini et al. 1991, Clark 1994, Wu et al. (1959). It consists of a nearly complete, but poorly 1997, Buckley and Brochu 1999, Pol 1999, 2003, preserved, skull lacking much of the skull table and Buckley et al. 2000, Ortega et al. 2000, Pol and Norell occiput posterior to the left orbit and right supra- 2004). Although its membership in Mesoeucrocodylia temporal fenestra. A nearly complete mandible is is unquestioned, at present its taxonomic and preserved in near articulation, but displaced to the left phylogenetic status remains unclear. Inclusion of new lateral side. The palatal region is well preserved and information from the Malagasy taxon clarifies aspects most of the sutures on the snout and preserved skull of Araripesuchus morphology and phylogenetic analysis table can be discerned. places it in a clade that is the sister group to Neosuchia. An almost complete skeleton of A. gomesii was later Additionally, a number of authors have raised recovered from the same formation (AMNH 24450; doubts regarding the membership of Araripesuchus Hecht 1991). The specimen is preserved on two slabs New Araripesuchus from Madagascar 257 Figure 2. MUCPV 269, Araripesuchus patagonicus. Skull in dorsal view (A) and ventral view (B). Scale ¼ 1 cm. showing both dorsal and ventral aspects. AMNH of a nearly complete skull and the anterior half of the 24450 has been acid prepared from both sides postcranium. The anterior-most end of the rostrum is revealing extraordinary preservation and detail. missing in the type and the dorsal