Dental homologies and evolutionary transformations in Caviomorpha (Hystricognathi, Rodentia): new data from the Paleogene of Peruvian Amazonia Myriam Boivin, Laurent Marivaux To cite this version: Myriam Boivin, Laurent Marivaux. Dental homologies and evolutionary transformations in Caviomor- pha (Hystricognathi, Rodentia): new data from the Paleogene of Peruvian Amazonia. Historical Biology, Taylor & Francis, 2020, 32 (4), pp.528-554. 10.1080/08912963.2018.1506778. hal-01870927 HAL Id: hal-01870927 https://hal.umontpellier.fr/hal-01870927 Submitted on 17 Jun 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Page 1 of 118 Historical Biology 1 2 3 Dental homologies and evolutionary transformations in Caviomorpha (Hystricognathi, 4 5 Rodentia): new data from the Paleogene of Peruvian Amazonia 6 7 8 9 10 a* a 11 Myriam Boivin and Laurent Marivaux 12 13 14 15 a Laboratoire de Paléontologie, Institut des Sciences de l’Évolution de Montpellier (ISE-M), c.c. 16 For Peer Review Only 17 18 064, Université de Montpellier, CNRS, IRD, EPHE, place Eugène Bataillon, F-34095 19 20 Montpellier Cedex 05, France. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 *Corresponding author. Tel: 334 67 14 49 11. Email: [email protected]. 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 2 of 118 1 2 3 Abstract 4 5 6 Dental homologies and evolutionary transformations within caviomorph rodents have long been 7 8 disputed. Here, we join to these debates in providing new insights from the dental morphology of 9 10 11 Paleogene caviomorphs from Peruvian Amazonia (Contamana and Shapaja). Their analyses and 12 13 comparisons with many hystricognaths allows (1) to generalize some hypotheses previously 14 15 proposed about occlusal morphology of caviomorph cheek teeth, and (2) to propose new ones. In 16 For Peer Review Only 17 18 caviomorphs, the third crest of upper teeth would correspond either to a mesoloph or to a 19 20 mesolophule or to a combination of both. The transformation from a pentalophodont pattern to a 21 22 tetralophodont pattern would be explained by the disappearance of the metaloph. Likewise, the 23 24 25 transformation from a tetralophodont pattern to a trilophodont pattern is observed by the loss of 26 27 the third crest. A direct transformation from a pentalophodont pattern to a trilophodont pattern is 28 29 also observed. Concerning lower teeth, discrepancies of homologies are centered on the mesial 30 31 cristids, which can be notably distinguished depending on their compositions and connections 32 33 34 with other structures. The ancestral patterns of caviomorph lower molars and dp4s were likely 35 36 tetralophodont and pentalophodont, respectively. However, schemes with five and four (even 37 38 three) transverse cristids cannot be ruled out for the two loci, respectively. 39 40 41 Keywords: Caviomorph rodents, Peru, South America, dental morphology, hypotheses of 42 43 44 homologies. 45 46 47 48 49 50 51 52 53 54 55 56 57 2 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 3 of 118 Historical Biology 1 2 3 Introduction 4 5 6 Homology is usually considered as a fundamental concept in biology, which ‘occupies a central 7 8 position in comparative studies’, dixit de Pinna (1991). As part of morphological analyses, the 9 10 11 identification of structures corresponding to primary homology (sensu de Pinna 1991) is a 12 13 prerequisite, but is not always obvious and often a matter of debate. For instance, the case of the 14 15 distal crests of upper teeth in caviomorph rodents (Caviomorpha Wood, 1955 or New World 16 For Peer Review Only 17 18 hystricognaths) has long been the subject of intense discussions. The diverging proposed 19 20 homologies have resulted in competing hypotheses regarding the sister group identification of 21 22 caviomorphs and, hence, in diverging opinions about their geographic origin. Indeed, two main 23 24 25 hypotheses were proposed during the twentieth century: 26 27 (1) some authors have advocated that a tetralophodont pattern would be the ancestral 28 29 condition for caviomorph upper teeth, and that these rodents would be closely related to 30 31 North American rodents: Paramyidae or Sciuravidae (Wood 1949) and then Franimorpha 32 33 34 (Reithroparamyinae, Protoptychidae, Prolapsus, Guanajuatomys, and later 35 36 Cylindrodontidae; Wood 1980; see also Wood 1950, 1959, 1962, 1965, 1972, 1973, 1974, 37 38 1975, 1983, 1984, 1985a, b, 1993; Wood and Patterson 1959; Patterson and Wood 1982); 39 40 41 (2) in contrast, some others have defended the hypothesis according to which the upper teeth 42 43 of caviomorphs would be primitively pentalophodont, with a pattern similar to that of Old 44 45 World hystricognaths (Phiomorpha [Thryonomyidae, Bathyergoidea, and Hystricoidea] 46 47 48 sensu Lavocat 1967). On the basis of these hypotheses of morphological homologies, an 49 50 African origin of caviomorphs was postulated (Lavocat 1969, 1971, 1973, 1974a, b, 1976, 51 52 1977a, b, 1980; Hoffstetter 1971, 1972, 1975, 1976; Hoffstetter and Lavocat 1970). 53 54 55 56 57 3 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 4 of 118 1 2 3 Since then, the reassessment of the potential links between North American reithroparamyids 4 5 and hystricognaths (Dawson 1977; Korth 1984; Meng 1990), as well as the formalization of the 6 7 8 caviomorph-phiomorph relationships via phylogenetic analyses based on morphological (e.g., 9 10 George 1993; Luckett and Hartenberger 1993; Marivaux et al. 2002, 2004) and molecular data 11 12 (e.g., Nedbal et al. 1996; Huchon et al. 2000, 2002, 2007; Huchon and Douzery, 2001; 13 14 15 Montgelard et al. 2008; Fabre et al. 2012) marked the end of this hotly debated biogeographic 16 For Peer Review Only 17 issue. The hypothesis of an African origin for caviomorphs, put forward by Lavocat (and 18 19 collaborators), is now a well-accepted consensus within the scientific community. However, 20 21 22 critical factors such as the mode and precise timing of the Afro-South-American dispersal(s), and 23 24 the pathways by which this (these) dispersal(s) occurred remain still entirely unknown. 25 26 Over the past decades, many authors have studied dental homologies and evolutionary 27 28 patterns in caviomorphs (e.g., Jaeger 1989; Vucetich and Verzi 1994; Verzi et al. 2018), notably 29 30 31 in erethizontoids (e.g., Candela 1999, 2002) and in octodontoids (e.g., Carvalho and Salles 2004; 32 33 Candela and Rasia 2012; Candela 2015; Verzi et al. 2014, 2016, 2017, 2018). The debates 34 35 regarding the dental homologies in caviomorphs have then shifted to other structures, such as the 36 37 38 mesial cristids of lower teeth (Candela 2002; Carvalho and Salles 2004; Candela and Rasia 2012; 39 40 Candela 2015; Verzi et al. 2014, 2016, 2017, 2018). 41 42 Despite the modern and Neogene high diversity of caviomorphs, the early evolutionary history 43 44 45 of these rodents has long remained obscure. Until recently, most of the Paleogene caviomorph 46 47 assemblages were primarily concentrated at middle (Bolivia, Brazil, Chili, southern Peru, and 48 49 Uruguay) and high (Argentina) latitudes of South America (15/19; see Boivin et al. 2017b and 50 51 citations therein). By contrast, lower latitudes have long remained poorly documented (Santa 52 53 54 Rosa and Lircay, Peru; Foz do Breu and Cachoeira São Salvador, Brazil; Hartenberger et al. 55 56 57 4 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 5 of 118 Historical Biology 1 2 3 1984; Frailey and Campbell 2004; Ribeiro et al. 2013, Kerber et al. 2017). During the last 4 5 decade, the continuing field efforts in Peruvian Amazonia (Contamana and Tarapoto areas) have 6 7 8 led to the discovery of about twenty Paleogene localities yielding many fossils of caviomorphs 9 10 (mainly dental remains; Antoine et al. 2016; Boivin et al. 2017a, b, 2018). They document three 11 12 South American Land Mammal Ages (SALMA): Barrancan (late Middle Eocene; Contamana), 13 14 15 Tinguirirican (Early Oligocene; Tarapoto, Shapaja section) and Deseadan (Late Oligocene; 16 For Peer Review Only 17 Contamana). The late Middle Eocene localities have so far yielded the oldest known 18 19 representatives of the group in South America (Antoine et al. 2012; Boivin et al. 2017a). The 20 21 22 studies of these fossils have revealed a rich specific diversity, most of the species being new for 23 24 science (Antoine et al. 2012; Boivin 2017; Boivin et al. 2017a, b, 2018). These ancient fossils 25 26 have provided unusual dental morphologies for caviomophs, the descriptions and detailed 27 28 comparisons of which have led us to formulate new hypotheses regarding some structural 29 30 31 homologies, and also to further our understanding regarding some aspects of their evolutionary 32 33 trends. All these observations were at the origin of an updated dental nomenclature, which was 34 35 proposed in Boivin et al., 2017a, b, 2018). In this paper, we propose a detailed overview of the 36 37 38 dental homology and evolutionary transformation hypotheses that we have formulated in light of 39 40 the dental material from the Paleogene rodent-bearing localities of Contamana and 41 42 Tarapoto/Shapaja.