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Fossil History of Chameleons

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Chameleons are a highly characteristic and morphologically specialized group of lizards, with more than 190 species in 11 accepted genera (Appendix). Apart from recent introductions, the group is mainly distributed across southern Europe, Africa, the Middle East, southern India, Sri Lanka, and Madagascar, reaching its greatest diversity in the latter (Chapter 7). Ingroup relationships of living chameleons are based strongly on molecular studies (e.g., Townsend and Larson, 2002, 2011a; Tolley et al., 2013), particularly at the species level, where morphological characters are less reliable (Tolley et al., 2004, 2011; Tilbury and Tolley, 2009; Townsend et al., 2009; Gehring et al., 2012). Uncertainties as to the relationships of chameleons with agamids, as well as conflicting ideas as to the position of Iguania as a whole, have hampered the study of their origin and early history and, again, much of the recent literature on this topic has also been based on molecular analyses (e.g., Macey et al., 2000a; Townsend et al., 2011a). Fossils have the potential to provide valuable information regarding the early evolution and paleobiogeography of the group but, unfortunately, the fossil record of chameleons is extremely limited (Tables 9.1, 9.2, Fig. 9.1), there are no complete specimens, and representatives of the group appear surprisingly late (Early Miocene, ca. 21 Mya) in contrast to other squamates.
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... Their relationships to other squamates, however, are yet not fully resolved, mostly because of the uncertainty of the position of Iguania, but it is widely accepted that Chamaeleonidae constitute a group within the iguanian clade Acrodonta (Estes et al. 1988;Townsend et al. 2004;Kumazawa 2007;Conrad 2008;Vidal and Hedges 2009;Gauthier et al. 2012;Wiens et al. 2012;Pyron et al. 2013; Communicated by: Sven Thatje Electronic supplementary material The online version of this article (doi:10.1007/s00114-016-1336-5) contains supplementary material, which is available to authorized users. et al. 2015), even if their affinities with Agamidae are a matter of debate, with different topologies arising on the basis of morphological and molecular data (Bolet and Evans 2013;Tolley and Menegon 2013). ...
... Despite the broad geographic distribution among extant taxa, the fossil record of Chamaeleonidae is rather patchy (Bolet and Evans 2013). A Cretaceous origin of the group is commonly accepted based on molecular data ), but with their first fossil record dating back to the early Miocene (Moody and Roček 1980;Pickford 1986), such molecular divergence date cannot be thoroughly tested. ...
... A Cretaceous origin of the group is commonly accepted based on molecular data ), but with their first fossil record dating back to the early Miocene (Moody and Roček 1980;Pickford 1986), such molecular divergence date cannot be thoroughly tested. The dispersal of chamaeleonids to Europe and Asia seems to have occurred later (Bolet and Evans 2013;); indeed, their Neogene record on the European continent is rather scanty with few, scattered occurrences only across the early to middle Miocene of Central Europe (Moody and Roček 1980;Böhme and Ilg 2003;Čerňanský 2010;Bolet and Evans 2013). ...
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The fossil record of Chamaeleonidae is very scarce and any new specimen is therefore considered important for our understanding of the evolutionary and biogeographic history of the group. New specimens from the early Miocene of Aliveri (Evia Island), Greece constitute the only fossils of these lizards from southeastern Europe. Skull roofing material is tentatively attributed to the Czech species Chamaeleo cf. andrusovi, revealing a range extension for this taxon, whereas tooth-bearing elements are described as indeterminate chamaeleonids. The Aliveri fossils rank well among the oldest known reptiles from Greece, provide evidence for the dispersal routes of chameleons out of Africa towards the European continent and, additionally, imply strong affinities with coeval chamaeleonids from Central Europe.
... Chameleons are a relatively recent family (Chamaeleonidae) of lizards that diverged from their sister group, the Agamidae, in the Late Cretaceous (ca. 90 My; Townsend et al. 2011;Bolet and Evans 2013;Tolley et al. 2013), whereas the divergence between most other lizard families occurred in the Jurassic to Middle Cretaceous (Vidal and Hedges 2009). Chameleons are thought to have originated in Africa and then dispersed to Madagascar, the Seychelles, the Comoros Islands, South India, Oman, Yemen, and the Mediterranean Coast (Tolley et al. 2013) where they are currently found. ...
... Chameleons are thought to have originated in Africa and then dispersed to Madagascar, the Seychelles, the Comoros Islands, South India, Oman, Yemen, and the Mediterranean Coast (Tolley et al. 2013) where they are currently found. Despite the fact that Chamaeleonidae have existed for about 90 My, the fossil register of chameleons only starts in the Lower Miocene (Townsend et al. 2011;Bolet and Evans 2013). Moreover, the number of fossils that can be assigned to genera (or species) within this family is rather limited. ...
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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.
... Using the combined four-gene dataset, a time-calibrated phylogeny was estimated in Bayesian Evolutionary Analysis Sampling Trees (BEAST2, Bouckaert et al., 2014), with five outgroup taxa from the genera Calumma, Furcifer, and Trioceros included. With a paucity of fossil data for Chamaeleo and uncertainty as to the taxonomic assignment of the few fossils available (Bolet and Evans, 2014), a secondary calibration point from Tolley et al. (2013) for the date of the split between Chamaeleo and other genera within the polytomy was incorporated. A lognormal distribution with an offset mean age of 43 Myr, and a standard deviation of 5 Myr, was applied to the root node. ...
Article
Molecular phylogenetics and the application of species delimitation methods have proven useful in addressing limitations associated with morphology based taxonomy and have highlighted the inconsistencies in the current taxonomy for many groups. For example, the genus Chamaeleo, which comprises 14 species with large distributions across mainland Africa and parts of Eurasia, exhibits relatively minor phenotypic differentiation between species, leading to speculation regarding the presence of cryptic diversity in the genus. Therefore, the aims of the present study were to construct a robust and comprehensive phylogeny of the genus and highlight potential species-level cryptic diversity. Additionally, we sought to ascertain the most likely biogeographic origin of the genus and understand its spatio-temporal diversification. Accordingly, we made use of species delimitation methods (Bayesian and divergence based) to investigate the extent of cryptic diversity in Chamaeleo, and applied an ancestral area reconstruction to examine the biogeographic origin of the group. Our phylogenetic analysis suggested the presence of at least 18 taxa within Chamaeleo. Notably, three taxa could be recognised within C. dilepis, none of which are equivalent in context with any of the currently described subspecies. There were also three taxa within C. gracilis and two within C. anchietae. The single available tissue specimen identified as C. necasi was embedded within the C. gracilis clade. Our ancestral area reconstruction points to a southern African/Zambezian origin for Chamaeleo, with diversification beginning during the cooling and aridification of Africa that characterised the Oligocene Epoch, ca. 23-34 Mya (Million years ago). Species-level diversification began in the Miocene Epoch (ca. 5-23 Mya), possibly tracking the aridification that triggered the shift from forest to more open, mesic savanna for most clades, but with tectonic events influencing speciation in a Palearctic clade. These findings lay the foundation for a future integrative taxonomic re-evaluation of Chamaeleo, which will be supported with additional lines of evidence before implementing any taxonomic changes.
... European fossil chamaeleons are rather important in the context of the poor fossil record of this family, since this area is one of the richest worldwide in term of remains attributable to these lizards (Böhme and Ilg 2003;Bolet and Evans 2013a;Georgalis et al. 2016a). Central Europe, in particular, has yielded an unexpectedly high number of Neogene chamaeleon fossils, if compared with the very scanty palaeontological record of the family in the rest of the world (even though this can be caused simply by a less extensive systematic research activity in Africa and Asia). ...
Article
Lizards were and still are an important component of the European herpetofauna. The modern European lizard fauna started to set up in the Miocene and a rich fossil record is known from Neogene and Quaternary sites. At least 12 lizard and worm lizard families are represented in the European fossil record of the last 23 Ma. The record comprises more than 3000 occurrences from more than 800 localities, mainly of Miocene and Pleistocene age. By the beginning of the Neogene, a marked faunistic change is detectable compared to the lizard fossil record of Palaeogene Europe. This change is reflected by other squamates as well and might be related to an environmental deterioration occurring roughly at the Oligocene/Miocene boundary. Nevertheless, the diversity was still rather high in the Neogene and started to decrease with the onset of the Quaternary glacial cycles. This led to the current impoverished lizard fauna, with the southward range shrinking of the most thermophilic taxa (e.g., agamids, amphisbaenians) and the local disappearance of other groups (e.g., varanids). Our overview of the known fossil record of European Neogene and Quaternary lizards and worm lizards highlighted a substantial number of either unpublished or poorly known occurrences often referred to wastebasket taxa. A proper study of these and other remains, as well as a better sampling of poorly explored time ranges (e.g., Pliocene, Holocene), is needed and would be of utmost importance to better understand the evolutionary history of these reptiles in Europe.
... This interpretation was followed by Estes (1983) who noted that the quadrate in Anqingosaurus appeared vertical and columnar, as in chameleons, and that the postdentary region of the mandible is enlarged. However, a recent review of chameleon history (Bolet and Evans, 2014) concluded that Anqingosaurus did not show any definitive characteristics of Chamaeleonidae. ...
... This interpretation was followed by Estes (1983) who noted that the quadrate in Anqingosaurus appeared vertical and columnar, as in chameleons, and that the postdentary region of the mandible is enlarged. However, a recent review of chameleon history (Bolet and Evans, 2014) concluded that Anqingosaurus did not show any definitive characteristics of Chamaeleonidae. ...
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Although the Late Cretaceous lizard fauna of China and Mongolia is relatively well-known, information on Paleocene lizards from the same region is currently limited. Several species of lizards have been reported from the Paleocene Wanghudun and Doumu formations of Qianshan Basin on the basis of fragmentary specimens, namely Agama sinensis Hou, 1974, Anhuisaurus huainanensis Hou, 1974, Anqingosaurus brevicephalus Hou, 1976, Changjiangosaurus huananensis Hou, 1976, Qianshanosaurus huangpuensis Hou, 1974, and Tinosaurus doumuensis Hou, 1974. In this paper, we review all the reported material of these taxa with the aid of new technology, including CT scanning, and according to current views of squamate relationships and classification. Revised descriptions and classifications are given for each taxon, leading to changes in our understanding of faunal composition. This, in turn, reveals greater morphological and ecological diversity among the Paleocene lizards of the Qianshan Basin, including the occurrence of a varaniform (IVPP V 22767), and the reinterpretation of Anqingosaurus as a possible burrower. Further work on the Paleocene Qianshan lizards is ongoing and the discovery of new specimens may help to solve the puzzles these strange lizards have posed.
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The genus Chamaeleo, currently subdivided into two sub-genera, Chamaeleo (Chamaeleo) and Chamaeleo (Trioceros) (Klaver & Böhme 1986), is reviewed from both a morphological and genetic basis and it is concluded that the two subgenera are sufficiently distinct as to warrant their formal elevation to seperate and distinct genera. Evaluation of the soft anatomy and several other characters provide sufficient basis for making this distinction. The proposed change is supported by the demonstration of monophyletic groupings (based on two mitochondrial and one nuclear gene) consistent with distinct genera.
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