据加拿大《世界日报》8月8日讯：加拿大古生物学家近日在巴西小镇Minas Gerais发现一种活跃在7000万年前的新物种头骨化石，并将它命名为Pissarrachampsa sera。该物种属于波罗鳄，它有着狗一样的头颅，巨大的犬齿，和适合在陆地行走的四肢，猎食对象包括恐龙等大型动物，可以说是“恐龙杀手”。
波罗鳄属于鳄形动物中的中真鳄家族（Mesoeucrocodylia），中真鳄一族目前仅有帕切克波罗鳄（Baurusuchus pachecoi）为代表，学界尚无这一族群内部成员关系的资料。发现上述新物种的头骨化石，对了解已灭绝的帕切克波罗鳄有很大的帮助。
上述发现发表在近期出版的《公共科学图书馆—综合》（PLoS ONE）上。
生物探索推荐英文论文摘要：
Background
Baurusuchidae is a group of extinct Crocodyliformes with peculiar, dog-faced ***s, hypertrophied canines, and terrestrial, cursorial limb morphologies. Their importance for crocodyliform evolution and biogeography is widely recognized, and many new taxa have been recently described. In most phylogenetic analyses of Mesoeucrocodylia, the entire clade is represented only by Baurusuchus pachecoi, and no work has attempted to study the internal relationships of the group or diagnose the clade and its members.
Methodology/Principal Findings
Based on a nearly complete *** and a referred partial *** and lower jaw, we describe a new baurusuchid from the Vale do Rio do Peixe Formation (Bauru Group), Late Cretaceous of Brazil. The taxon is diagnosed by a suite of characters that include: four maxillary teeth, supratemporal fenestra with equally developed medial and anterior rims, four laterally visible quadrate fenestrae, lateral Eustachian foramina larger than medial Eustachian foramen, deep depression on the dorsal surface of pterygoid wing. The new taxon was compared to all other baurusuchids and their internal relationships were examined based on the maximum parsimony analysis of a discrete morphological data matrix.
Conclusion
The monophyly of Baurusuchidae is supported by a large number of unique characters implying an equally large morphological gap between the clade and its immediate outgroups. A complex phylogeny of baurusuchids was recovered. The internal branch pattern suggests two main lineages, one with a relatively broad geographical range between Argentina and Brazil (Pissarrachampsinae), which includes the new taxon, and an endemic clade of the Bauru Group in Brazil (Baurusuchinae).
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