1Programa em Pós-graduação em Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Seção de Paleontologia, Museu de Ciências Naturais da Fundação Zoobotânica do Rio Grande do Sul, Rua Dr. Salvador França, 1427, 90690-0, Porto Alegre, RS, Brasil. 2Bolsista de Doutorado CNPq. 3Bolsista em aperfeiçoamento FAPEMA. 4Centro de Pesquisa de Historia Natural e Arqueologia do Maranhão, Rua do Giz, 59 - Praia Grande - 65010-
680, Centro Histórico de São Luís, São Luís, MA, Brasil. 5Departamento de Biologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal do Maranhão (UFMA), Avenida dos Portugueses, s/n0, Campus Universitário do Bacanga, 65085-580, São Luis, MA, Brasil.
First record of Madtsoiidae (Serpentes) from the Middle Cretaceous (Albian-Early Cenomanian) of Brazil
Annie Schmaltz Hsiou1,2, Ronny A. B. Santos3,4,5 & Manuel Alfredo Medeiros4,5
The extinct family Madtsoiidae (Late Cretaceous-Pleistocene) includes fossils mainly known by vertebral remains, although there are additional records of cranial elements in the
Paleogenous and Neogenous of Australia. There are several works about the systematic position of Matsoiidae. For many times the group was considered as being a Boidae, a lineage of very primitive snakes, or a basal alethinophidian monophyletic group. Recently, new hypothesis was proposed considering Madtsoiidae as archaic, non-alethinophidian snakes, or even belonging the extant clade Macrostomata. South American (Madtsoiidae?) fossils are represented in the Late Cretaceous of Argentina (Los Alamitos Formation) by three genera (Rionegrophis, Alamitophis and Patagoniophis) with four species, all of them consisting of isolated trunk vertebrae, also reported for the Late Cretaceous of Bolivia
(undetermined fragments). In the Paleogenous, the family is present in the Early Paleocene of Argentina (Rio Chico Formation) and Early Eocene of Brazil (Itaboraí Basin), represented by Madtsoia. Here we report the first Middle Cretaceous vertebral remains of Madtsoiidae, collected in Falésia do Sismito and Laje do Coringa fossiliferous sites, Cajual Island (early Cenomanian deposits of the Alcântara Formation, Itapecuru Group), northeastern Brazil. The material is housed at Centro de Pesquisa de História Natural e Arqueologia do Maranhão (CPHNAMA), in São Luiz, Maranhão State, and consists of two small isolated trunk vertebrae, probably belonging to the middle (VT-1222) and posterior
(VT-1116) trunk region. The fossils are assigned to Madtsoiidae by the following combination of characters: middle and posterior trunk vertebrae with moderately or well developed haemal keel; paracotylar and parazygantral foramina present; prezygapophyseal processes absent; and diapophyses relatively wide, exceeding the width across the prezygapophyses at least in posterior trunk vertebrae. This is the oldest Brazilian snake and the oldest South American record for the family Madtsoiidae.
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