Dollion Alexis Y, Cornette Raphaël, Tolley Krystal A, Boistel Renaud, Euriat Adelaïde, Boller Elodie, Fernandez Vincent, Stynder Deano, Herrel Anthony
UMR 7179 CNRS/MNHN, Département d'Ecologie et Gestion de la Biodiversité, Muséum National d'Histoire Naturelle (MNHN), 57 rue Cuvier, Case postale 55,75231, Paris Cedex 5, France.
Naturwissenschaften. 2015 Feb;102(1-2):1254. doi: 10.1007/s00114-014-1254-3. Epub 2015 Jan 21.
The evolutionary history of chameleons has been predominantly studied through phylogenetic approaches as the fossil register of chameleons is limited and fragmented. The poor state of preservation of these fossils has moreover led to the origin of numerous nomen dubia, and the identification of many chameleon fossils remains uncertain. We here examine chameleon fossil fragments from the Early Pliocene Varswater formation, exposed at the locality of Langebaanweg "E" Quarry along the southwestern coast of South Africa. Our aim was to explore whether these fossil fragments could be assigned to extant genera. To do so, we used geometric morphometric approaches based on microtomographic imaging of extant chameleons as well as the fossil fragments themselves. Our study suggests that the fossils from this deposit most likely represent at least two different forms that may belong to different genera. Most fragments are phenotypically dissimilar from the South African endemic genus Bradypodion and are more similar to other chameleon genera such as Trioceros or Kinyongia. However, close phenetic similarities between some of the fragments and the Seychelles endemic Archaius or the Madagascan genus Furcifer suggest that some of these fragments may not contain enough genus-specific information to allow correct identification. Other fragments such as the parietal fragments appear to contain more genus-specific information, however. Although our data suggest that the fossil diversity of chameleons in South Africa was potentially greater than it is today, this remains to be verified based on other and more complete fragments.
由于变色龙的化石记录有限且不完整,其进化历史主要通过系统发育方法进行研究。此外,这些化石保存状况不佳,导致大量存疑名称的出现,许多变色龙化石的鉴定仍然不确定。我们在此研究了上新世早期瓦尔兹瓦特组的变色龙化石碎片,这些碎片出土于南非西南海岸兰格班维格“E”采石场。我们的目的是探讨这些化石碎片是否可以归为现存的属。为此,我们基于现存变色龙以及化石碎片本身的显微断层成像,采用了几何形态测量方法。我们的研究表明,该矿床的化石很可能至少代表两种不同的形态,它们可能属于不同的属。大多数碎片在表型上与南非特有属侏儒变色龙不同,而与其他变色龙属如三角变色龙属或肯尼亚变色龙属更为相似。然而,一些碎片与塞舌尔特有属古变色龙或马达加斯加属叉角避役属之间存在密切的表型相似性,这表明其中一些碎片可能没有足够的属特异性信息来进行正确鉴定。不过,其他碎片,如顶骨碎片,似乎包含更多的属特异性信息。虽然我们的数据表明南非变色龙的化石多样性可能比现在更大,但这仍有待基于其他更完整的碎片进行验证。