NEW MATERIAL OF DADADON ISALOI (CYNODONTIA, TRAVERSODONTIDAE) FROM THE TRIASSIC OF MADAGASCAR
NEW MATERIAL OF DADADON ISALOI (CYNODONTIA, TRAVERSODONTIDAE) FROM THE TRIASSIC OF MADAGASCAR
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DOI：
10.1080/02724634.2011.618154
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发表时间：
2011-01-01
影响因子：
1.4
通讯作者：
Wyss, Andre R.
中科院分区：
文献类型：
--
作者：
Ranivoharimanana, Lovasoa;Kammerer, Christian F.;Wyss, Andre R.
本文记述了马达加斯加西南部三叠纪的横齿类Cnodondon Dadadon isaloi的新材料。新材料包括一个完整的、保存完好的头骨(FMNH PR2232)和一个不相关的部分下颌骨(UA 10608)。新材料揭示了达达顿形态的几个新方面。新发现的诊断Dadadon的自身形态包括具有后副尖端的第四上切牙，局限于额部的深眶间凹陷，以及非常高、坚固的额中隆起。Dadadon可以进一步区别于类似的脊齿类和Santacruzodon类，因为它们的前额较短、较宽，具有明显的背侧凹陷，坚固的前外侧突起悬在眼眶上方，上后尖牙的前扣带中有一个尖端，以及相对拉长的、有条纹的圆锥形上门牙。在结合了新标本数据的修改后的系统发育分析中，Dadadon被发现与Massetogna和Santacruzodon属于一个支系。这支是支持良好的横齿亚支Gomphodontosuchinae的姊妹分类群。马达加斯加的‘基本Isalo II’狗牙科动物群在组成上更类似于南美洲，而不是非洲大陆，尽管这可能是因为大陆上缺乏拉迪安-卡尼安疗法化石，而不是实际的生物地理模式。
New material of the traversodontid cynodont Dadadon isaloi from the Triassic of southwestern Madagascar is described. The new material consists of a complete, well-preserved skull (FMNH PR 2232) and an unassociated, partial lower jaw (UA 10608). The new material reveals several novel aspects of Dadadon's morphology. Newly recognized autapomorphies that diagnose Dadadon include a fourth upper incisor with posterior accessory cusp, deep interorbital depressions confined to the frontals, and a very tall, robust mid-frontal ridge. Dadadon can further be distinguished from the similar traversodontids Massetognathus and Santacruzodon by the presence of shorter, broader prefrontals with prominent dorsal depressions, robust anterolateral processes overhanging the orbits, a single cusp in the anterior cingulum of the upper postcanines, and relatively elongate, striated, conical upper incisors. In a revised phylogenetic analysis incorporating data from the new specimens, Dadadon is recovered in a clade with Massetognathus and Santacruzodon. This clade is the sister taxon to the well-supported traversodontid subclade Gomphodontosuchinae. The 'basal Isalo II' cynodont fauna from Madagascar is more similar in composition to that of South America than to mainland Africa, although this is probably attributable to the lack of Ladinian-Carnian therapsid fossils on the mainland rather than an actual biogeographic pattern.