Department of Biological Sciences, Northern Illinois, University, DeKalb, Illinois United States of America.
Domaine des Sciences et Technologies, Mention Bassins Sédimentaires Evolution Conservation, Université d'Antananarivo, Antananarivo, Madagascar.
PLoS One. 2019 Feb 27;14(2):e0211789. doi: 10.1371/journal.pone.0211789. eCollection 2019.
We report here the first neoselachian fossil fauna from Eocene nearshore marine deposits of the Mahajanga Basin, northwestern Madagascar. The fauna includes seven species of shark: Nebrius blankenhorni, Brachycarcharias koerti, Galeocerdo eaglesomei, two species of Carcharhinus (one of which is described as a new species), Physogaleus, Rhizoprionodon and Sphyrna. Three species of rays were also recovered: Pristis, Myliobatis and an undetermined dasyatid ray. This fauna represents the first Cenozoic neoselachian fossil record from the Eocene of Madagascar and broadens our understanding of their evolutionary and biogeographic history in the southern hemisphere during this time. Although the diversity of the genera and species of the fauna is very low, the age and similarity of genera to those in Congo, west Africa, Arabia, Asia, Europe, and North, Central, and South America suggests that these genera were broadly distributed and diverse within the shallow marine settings of the Tethyan and southern provinces during middle and late Eocene.
我们在这里报告了第一个来自马达加斯加西北部马任加盆地始新世近岸海洋沉积物的新鲨鱼类化石动物群。该动物群包括 7 种鲨鱼： Nebrius blankenhorni、Brachycarcharias koerti、Galeocerdo eaglesomei、两种 Carcharhinus（其中一种被描述为新种）、Physogaleus、Rhizoprionodon 和 Sphyrna。还回收了三种鳐鱼：Pristis、Myliobatis 和一种未确定的长尾鲨科鳐鱼。该动物群代表了马达加斯加始新世新生代新鲨鱼类化石的第一个记录，拓宽了我们对它们在南半球这段时间进化和生物地理历史的理解。尽管该动物群的属和种的多样性非常低，但与非洲刚果、西非、阿拉伯、亚洲、欧洲以及北美、中美洲和南美洲的属的年龄和相似性表明，这些属在中晚始新世的特提斯和南部海域的浅海环境中广泛分布且多样。
