Morphometric Analysis of Chameleon Fossil Fragments from the Early Pliocene of South Africa: a New Piece of the Chamaeleonid History
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Sci Nat (2015) 102:2 DOI 10.1007/s00114-014-1254-3 ORIGINAL PAPER Morphometric analysis of chameleon fossil fragments from the Early Pliocene of South Africa: a new piece of the chamaeleonid history Alexis Y. Dollion & Raphaël Cornette & Krystal A. Tolley & Renaud Boistel & Adelaïde Euriat & Elodie Boller & Vincent Fernandez & Deano Stynder & Anthony Herrel Received: 25 September 2014 /Revised: 1 December 2014 /Accepted: 3 December 2014 # Springer-Verlag Berlin Heidelberg 2015 Abstract The evolutionary history of chameleons has been pre- fragments are phenotypically dissimilar from the South African dominantly studied through phylogenetic approaches as the fossil endemic genus Bradypodion and are more similar to other cha- register of chameleons is limited and fragmented. The poor state meleon genera such as Trioceros or Kinyongia.However,close of preservation of these fossils has moreover led to the origin of phenetic similarities between some of the fragments and the Sey- numerous nomen dubia, and the identification of many chame- chelles endemic Archaius or the Madagascan genus Furcifer leon fossils remains uncertain. We here examine chameleon fos- suggest that some of these fragments may not contain enough sil fragments from the Early Pliocene Varswater formation, ex- genus-specific information to allow correct identification. Other posed at the locality of Langebaanweg “E” Quarry along the fragments such as the parietal fragments appear to contain more southwestern coast of South Africa. Our aim was to explore genus-specific information, however. Although our data suggest whether these fossil fragments could be assigned to extant gen- that the fossil diversity of chameleons in South Africa was po- era. To do so, we used geometric morphometric approaches tentially greater than it is today, this remains to be verified based based on microtomographic imaging of extant chameleons as on other and more complete fragments. well as the fossil fragments themselves. Our study suggests that the fossils from this deposit most likely represent at least two Keywords Chamaeleonidae . Early Pliocene . Geometric different forms that may belong to different genera. Most morphometrics . Varswater formation . Langebaanweg Communicated by: Sven Thatje Electronic supplementary material The online version of this article (doi:10.1007/s00114-014-1254-3) contains supplementary material, which is available to authorized users. A. Y. Dollion : A. Herrel (*) R. Boistel : A. Euriat UMR 7179 CNRS/MNHN, Département d’Ecologie et Gestion de la IPHEP, Université de Poitiers UMR CNRS 7262, 6 rue Michel Biodiversité, Muséum National d’Histoire Naturelle (MNHN), 57 brunet, 86073 Poitiers, France rue Cuvier, Case postale 55,75231, Paris Cedex 5, France e-mail: [email protected] E. Boller : V. Fernandez ESRF (European Synchrotron Radiation Facility), 71 avenue des R. Cornette Martyrs, 38000 Grenoble, France UMR 7205 CNRS/MNHN/UPMC/EPHE, Institut de Systématique, Évolution, Biodiversité (ISYEB), 45 rue Buffon, 75005 Paris, France D. Stynder K. A. Tolley Department of Archaeology, Faculty of Science, University South African National Biodiversity Institute, Claremont, of Cape Town, Rondebosch, Cape Town 7701, South Africa Cape Town 7735, South Africa K. A. Tolley A. Herrel Department of Botany and Zoology, Stellenbosch University, Evolutionary Morphology of Vertebrates, Ghent University, K.L. Matieland 7602, South Africa Ledeganckstraat 35, 9000 Ghent, Belgium 2 Page 2 of 14 Sci Nat (2015) 102:2 Introduction The fossils from “E” Quarry are primarily derived from the Varswater geological formation. Four members are recog- Chameleons are a relatively recent family (Chamaeleonidae) nized in the most recent lithostratigraphic review of this for- of lizards that diverged from their sister group, the mation: the early Late Miocene Langeenheid Sandy Clay Agamidae, in the Late Cretaceous (ca. 90 My; Townsend Member (LSCM) and Konings Vlei Gravel Member et al. 2011; Bolet and Evans 2013; Tolley et al. 2013), (KVGM), and the Late Miocene/Early Pliocene Langeberg whereas the divergence between most other lizard families Quartzose Sand Member (LQSM) and Muishond Fontein Pel- occurred in the Jurassic to Middle Cretaceous (Vidal and letal Phosphate Member (MPPM) (Roberts 2006). The LQSM Hedges 2009). Chameleons are thought to have originated and the MPPM are extremely rich and have thus far produced in Africa and then dispersed to Madagascar, the Seychelles, the bulk of the “E” Quarry fossils, including the chameleon the Comoros Islands, South India, Oman, Yemen, and the specimens studied here. The LQSM is construed as primarily Mediterranean Coast (Tolley et al. 2013) where they are a floodplain and salt marsh deposit, while the MPPM is currently found. Despite the fact that Chamaeleonidae have interpreted as primarily a river channel deposit (Hendey existed for about 90 My, the fossil register of chameleons 1982;Roberts2006; Roberts et al. 2011). Two river channels, only starts in the Lower Miocene (Townsend et al. 2011; beds 3aS and 3aN, have been identified. While the temporal Bolet and Evans 2013). Moreover, the number of fossils relationship between these two beds remains unclear, bed 3aS that can be assigned to genera (or species) within this fam- appears to be the earlier of the two (Hendey 1981, 1984). In ily is rather limited. There are only seven described fossil any event, both river channels are thought to reflect a progres- species and two subfossil species from the Lower Miocene sive northward shift of the lower course of the proto-Berg to the Upper Pleistocene: Chamaeleo bavaricus (Schleich River. 1983;Böhme2003, 2010), Chamaeleo caroliquarti (Moody The LBW chameleon fossils studied here largely consist of and Roček 1980; Čerňanský 2010), Chamaeleo pfeili fragmented cranial bones. Although the taxonomic identifica- (Schleich 1984; Čerňanský 2011), Chamaeleo simplex tion of such fossils is difficult, these fossils were previously (Schleich 1994), Chamaeleo andrusovi (Čerňanský 2010), assumed to belong to the genus Bradypodion, the most wide- Chamaeleo sulcodentatus (Schleich 1994), Trioceros spread extant chameleon genus in South Africa. However, by jacksonii (Leakey 1965), and Chamaeleo chamaeleon the Early Oligocene, all chameleon genera had diverged from (Talavera and Sanchíz 1983). Furthermore, many of these one another (Tolley et al. 2013). Because all extant genera fossils are fragmented and correct identification has proven were present in the Early Pliocene, the fragments could poten- to be difficult, leading to the presence of some nomina tially belong to any African genus. They cannot, however, dubia (Čerňanský 2010, 2011). The only exception to those belong to any Malagasy genus, as the divergence between fragmented fossils is an intact skull from the Early Miocene African and Malagasy genera substantially predates the Early of Kenya dated at about 18 My (Hillenius 1978; Rieppel Pliocene (Tolley et al. 2013). Yet, the likelihood that these et al. 1992) and called Chamaeleo intermedius. fossils effectively belong to Bradypodion is high given that The evolutionary history of chameleons as documented by they are the dominant chameleon fauna across southern Africa the fossil record is fragmentary and scattered, and some pieces and probably have been in place since the mid-Miocene appear to be lacking as illustrated by the time gap of approx- (Tolley et al. 2008). During that period, an episodic global imately 67 My between the estimated origin of the temperature increase (mid-Miocene optimum) (Zachos et al. Chamaeleonidae and the first fossils recorded. Langebaanweg 2001;Böhme2003) probably facilitated the expansion of cha- “E” Quarry (LBW) (32° 58′ S, 18° 7′ E), located on the west meleons across southern Africa. Potentially, the ancestral for- coast of South Africa, is one of the few sites in the world to est habitat of chameleons dominated the landscape at this have produced chameleon fossils. This important fossil local- point in time (Tolley et al. 2008, 2013). Thereafter, declining ity was discovered accidentally during phosphate mining op- temperatures and a decrease in CO2 concentration favored the erations in the early nineteenth century. Although the LBW expansion of C4 vegetation (Rossouw et al. 2009), allowing fossils elicited interest from the scientific community from the for open habitats such as grassland and fynbos (typical shrub- time that they were discovered, their great antiquity was only land or heathland vegetation occurring in the Western Cape realized once systematic analyses began to be carried out on region) to expand, while forests contracted (see Tolley et al. them in the 1960s. Today, LBW is internationally recognized 2013). Bradypodion are known to occur in both forest and as one of the most faunally diverse Mio-Pliocene fossil local- open habitats, and given that the west coast habitat at the start ities in the world. Beyond the fossils of chameleons and other of the Pliocene would have been a mosaic of forest and more squamates, notable fossil representatives of mammalian or- open environments, it may thus have been suitable for ders such as Proboscidea, Carnivora, Artiodactyla, and Bradypodion and potentially other chameleons. Perissodactyla are also present (Hendey 1970a, b; Roberts Until now, the poor state of preservation and the degree of et al. 2011). fragmentation of the LBW chameleon fossils have prevented Sci Nat (2015) 102:2 Page 3 of 14 2 their precise identification to the genus level. Even so,