A new ornithuromorph bird from the Lower Cretaceous of South America

The fossil record of Early Cretaceous birds in South America has been restricted to members of Enantiornithes from the Crato Formation (Aptian) of Brazil. Here we describe a new genus and species of bird discovered at Pedra Branca Mine, Nova Olinda County, Ceará State, Brazil, which adds to the avian fossil record from the Crato Formation. The specimen is represented by an isolated foot that is exposed in plantar view. A plantarly displaced metatarsal III with a well-developed hypotarsus supports its referral to Ornithuromorpha, representing the oldest member of the clade reported for Gondwana. Its unique foot conformation indicates that it may belong to an unknown ornithuromorph clade with some cursory similarities to extant flightless ratites. The presence of Early Cretaceous ornithuromorphs in Brazil indicates that the clade was widespread in Gondwana during the Mesozoic. http://zoobank.org/urn:lsid:zoobank.org:pub:08333BA3-F231-4E61-9E89-105C7478AE31

南美洲早白垩世鸟类的化石记录此前仅局限于巴西克拉托组（Crato Formation，阿普第阶[Aptian]）的反鸟亚纲（Enantiornithes）成员。本文描述了一件发现于巴西塞阿拉州新奥林达县佩德拉布兰卡矿点的鸟类新属新种，该发现丰富了克拉托组的鸟类化石记录。该标本为一件孤立的足部化石，以跖面视图（plantar view）保存。一件具有发育良好的下距突（hypotarsus）的跖面移位第三跖骨，支持其归入今鸟亚形类（Ornithuromorpha），该类群代表冈瓦纳大陆（Gondwana）目前报道的该演化支最古老成员。其独特的足部构造表明，它可能隶属于一个此前未被发现的今鸟亚形类演化支，该类群与现存不会飞行的平胸总目（ratites）存在些许粗略的形态相似性。巴西早白垩世今鸟亚形类化石的发现，表明该演化支在中生代时期曾广泛分布于冈瓦纳大陆。http://zoobank.org/urn:lsid:zoobank.org:pub:08333BA3-F231-4E61-9E89-105C7478AE31