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A New Extinct Genus of Cavioidea (Rodentia, Hystricognathi) from the Miocene of Patagonia (Argentina) and the Evolution of Cavioid Mandibular Morphology

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Abstract

The family Caviidae is represented in modern faunas by cavies and maras, whereas the family Hydrochoeridae is represented by capybaras. The evolutionary origin of these families has been related to a diversity of plesiomorphic fossil forms (recorded from the late Oligocene up to the middle Miocene) traditionally grouped in the family “Eocardiidae”. These fossil forms were included, together with Caviidae and Hydrochoeridae, within the Cavioidea s.s. (sensu stricto), because they share high crowned cheek teeth, double-hearted occlusal surface, short lower incisors, and moderate hystricognathy. Within Cavioidea s.s., caviids and hydrochoerids were interpreted as forming its crown group, because they have unique craniomandibular and dental features. In this contribution, a new taxon of Cavioidea s.s. from the middle Miocene of central Patagonia, Argentina, is described, and its phylogenetic position is determined on the basis of a morphological cladistic analysis in which “eocardiids” were included. The study permits the understanding of the sequence of appearance of characters that originated the highly divergent morphology of crown-group cavioids. The analysis of the sequence of appearance of the characters that traditionally diagnosed the crown group indicates that these changes did not occur at the same time. On the contrary, many of these features seem to have appeared at different nodes of the evolutionary history of Cavioidea s.s. The remarkably derived morphology of modern cavioids is the result of a stepwise appearance of a mosaic of evolutionary innovations that originated gradually along the history of Cavioidea during the late-middle Miocene.

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Acknowledgments

We thank C. Deschamps (MLP) for improving the English version, P. Puerta (MEF) for his technical fieldwork, and L. Reiner (MEF) for laboratory work. Access to SEM lab was possible thanks to ALUAR Aluminio Argentino SAIC and the help of Mr. J. Groizard. We thank the curators E. Ruigómez (MPEF-PV), M. Reguero (MLP-PV), A. Kramarz (MACN-PV), D. Verzi (MLP), D. Romero (MMP), J. Flynn and J. Meng (AMNH), Christopher Norris and D. Brinkman (YPM PU), and K. Wellspring (ACM) for access to material under their care. We are especially thankful to D. Pol for his aid in the phylogenetic analysis. Fieldwork at Río Chico was supported by grants from the National Science Foundation to R. Kay. Fieldwork at El Petiso was funded by Fundación Egidio Feruglio, Ministerio de Educación (Chubut, Argentina). Comparisons with cavioid taxa for the phylogenetic analysis were made possible thanks to the Collection Study Grant (AMNH), an Ostrum Fund Grant (YPM, USA), PICT 38112 (M.G. Vucetich), and Fundación Egidio Feruglio.

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Authors and Affiliations

  1. Museo Paleontológico Egidio Feruglio, Av. Fontana 140, Trelew, U9100GYO, Chubut, Argentina

    María Encarnación Pérez

  2. Departamento Científico Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque s/n B1900FWA, La Plata, Argentina

    María Guiomar Vucetich

Authors
  1. María Encarnación Pérez
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  2. María Guiomar Vucetich
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Corresponding author

Correspondence to María Encarnación Pérez.

Appendices

Appendix 1. Description of Characters Used in Phylogenetic Analyses.

The following characters are treated as ordered: 12, 14, 16, 18-21, 23-25, 29, and 33

  1. (1)

    Length of the upper diastema: equal or longer then the molariform series (0); shorter than molariform series (1).

  2. (2)

    Mental foramen: absent (0); present (1).

  3. (3)

    Location of the mental foramen on the anterior region of the dentary: close to the dorsal margin of the dentary and opening dorsolaterally (0); at the dorsoventral midpoint of the lateral surface of the dentary and opening laterally (1).

  4. (4)

    Position of the mandibular foramen: behind the retromolar fossa (0); below the m3 (1).

  5. (5)

    Posteroventral projection of the posterior end of the mandibular symphysis: absent (0); present (1).

  6. (6)

    Development of posteroventral projection of the posterior end of the mandibular symphysis in lateral view: well developed, forming an elongate peg exposed in lateral view (0); moderately developed, only a low bulge projects ventrally and is marginally exposed in lateral view (1).

  7. (7)

    Labial edge of the condyle, that is the insertion point of m. masseter posterior, in posterior view: projecting laterally with respect to wall of the dentary, forming small knob (0); lacking a distinct knob, continuous with lateral wall of the dentary (1).

  8. (8)

    Medial edge of the condyle that is the insertion point of m. pterygoideus externus, in posterior view: projecting medially forming a shelf that overhangs the medial surface of the dentary (0); poorly developed projecting medially forming a small knob with respect to medial wall of the dentary (1).

  9. (9)

    Shape of the post-condylar process, in lateral view: squared-off, forming approximately a 90° angle (0); rounded (1).

  10. (10)

    Length of the post-condylar process: equal or longer than the anteroposterior length of the condyle (0); shorter than anteroposterior length of the condyle (1).

  11. (11)

    Height of the coronoid process compared to the position of the condyle: located at the same dorsoventral level as the condyle (0); located more ventrally than the condyle (1).

  12. (12)

    Anterior margin of the coronoid process: convex (0); straight (1); concave (2). This character treated as ordered.

  13. (13)

    Dorsal end of the coronoid process: pointed and posterodorsally projected (0); pointed and dorsally projected (1); blunt (2).

  14. (14)

    Dorsoventral position of the mandibular notch: located above the occlusal surface of the dental series (0); located at the same height as the occlusal surface of the dental series (1); located ventral to the occlusal surface of the dental series (2). This character treated as ordered.

  15. (15)

    Shape of the mandibular notch: concave (0); almost straight (1).

  16. (16)

    Dorsoventral position of the anteriormost point of the lunar notch: low, located ventral to the dorsoventral midpoint of the dentary (between the ventral edge of the dentary and the condyle) (0); located at the approximate dorsoventral midpoint of the dentary (1); high, located above the dorsoventral midpoint of the dentary (2). This character treated as ordered.

  17. (17)

    Posterior extension of the angular process: level with the post-condylar process (0); ending anterior to the post-condylar process (1); ending posterior to the post-condylar process (2).

  18. (18)

    Posterior extension of the root of the lower incisors: extending up to the level of m3 (0); extending up to the level of the posterior lobe of m2 (1); extending up to the level of the anterior lobe of m2 (2); extending up to the level of m1 (3). This character treated as ordered.

  19. (19)

    Location of the notch for the insertion of the tendon of the m. masseter medialis pars infraorbitalis with respect to the toothrow: located between p4 and m1 (0); located below m1 (1); located between m1 and m2 (2). This character treated as ordered.

  20. (20)

    Notch for the insertion of the tendon of the m. masseter medialis pars infraorbitalis: connected to the masseteric crest (0); isolated, located between the massteric crest and the horizontal crest (1); connected to the horizontal crest (2). This character treated as ordered.

  21. (21)

    Development of the masseteric crest: well developed, forming a shelf that projects laterally with respect to the lateral surface of the dentary (0); forming a well-developed ridge that fails to project with respect to the lateral surface of the dentary (1); absent or poorly developed as a thin and low ridge (2). This character treated as ordered.

  22. (22)

    Shape of the lateral crest (sensu Woods 1972): straight, projecting anteroventrally from the base of the coronoid process (0); curved, deflecting anteroventrally from the base of the coronoid process (1).

  23. (23)

    Anterior origin of the masseteric crest with respect to the toothrow: located below m1 (0); located below m2 (1); located below m3 or posterior to m3 (2). This character treated as ordered.

  24. (24)

    Posterior extension of the horizontal crest, in lateral view: extending up to the anterior margin of the mandibular condyle (0); approximately ending at the anteroposterior midpoint of the mandibular condyle (1); extending up to the posterior margin of the mandibular condyle (2). This character treated as ordered.

  25. (25)

    Development of the horizontal crest: absent or extremely reduced (0); present as a low and broad ridge (1); present as a conspicuous crest, forming a laterally projected shelf but lacking a dorsal fossa (2); well developed, forming a laterally projected shelf and bearing a fossa on its dorsal surface (3). This character treated as ordered.

  26. (26)

    Depth of the fossa located dorsal to the horizontal crest with respect to the dorsoventral depth of the notch for the insertion of the tendon of the m. masseter medialis pars infraorbitalis: notch deeper than fossa (0); fossa deeper than notch (1); notch and fossa equal in depth (2).

  27. (27)

    Alveolar protuberances (ventral outgrowth of the base of some molariform alveoli that projects ventrally from the ventral surface of the dentary): absent (0); present (1).

  28. (28)

    Development of alveolar protuberances: present as a small but distinct convexity on the ventral margin of the dentary (0); present as well-developed bulge on the ventral margin of the dentary (1).

  29. (29)

    Degree of hypsodonty: slightly hypsodont, having the root and the anteroposterior length of the occlusal surface longer than the height of the crown (0); mesodont, having the root and the anteroposterior length of the occlusal surface approximately equal to the height of the crown (1); protohypsodont, having the root and the anteroposterior length of the occlusal surface less than half the height of the crown (2); euhypsodont, lacking roots (3). This character treated as ordered.

  30. (30)

    Shape of the molars, in oclussal view: not forming lobes (0); formed by triangular lobes (1); formed by heart-shaped lobes (2); formed by two laminar lobes, the posterior one being formed by a single lamina (3); formed by two laminar lobes, the posterior one being formed by at least four laminae (4).

  31. (31)

    Constriction of the apex in each lobe of the molars: absent (0); present (1).

  32. (32)

    Development of constriction of the apex in each lobe of the molars: poorly developed, with the apex of the lobes bearing a minor constriction (0); well developed, the constriction is present in both lobes of each tooth (1).

  33. (33)

    Transverse extension of the hypoflexus/id: transversely shorter than half of the width of the crown (0); extending from the margin up to the transverse midpoint of the crown (1); extending beyond the transverse midpoint of the crown (2). This character treated as ordered.

  34. (34)

    Shape of the hypoflexus/id in occlusal view: very narrow and short (0); V-shaped (1); narrow and very long (2); funnel shaped (3).

  35. (35)

    Longitudinal furrow on the labial wall of the upper molars and lingual wall of the lower molars: absent (0); present (1).

  36. (36)

    Position of the longitudinal furrow on the labial wall of the upper molars and the lingual wall of the lower molars: one furrow opposite the hypoflexus/id (0); one furrow on the posterior lobe (1); one furrow on each lobe (2).

  37. (37)

    Transverse dentine crest on the occlusal surface, located at the middle of each molar lobe: absent (0); present (1).

  38. (38)

    Length of p4-m1 with respect to the length of the m2-m3 (Wood and Patterson 1959): p4-m1 shorter than m2-m3 (0); p4-m1 approximately equal to m2-m3 (1).

  39. (39)

    Relative size of lower molars: m1 < m2 < m3 (0); m1 = m2 = m3 (1).

  40. (40)

    Relative size of the upper molars: P4 < M1 < M2 (0); P4 = M1 = M2 (1).

  41. (41)

    Replacement of deciduous premolar: unreplaced (0); with replacement (1).

  42. (42)

    Type of replacement: postnatal replacement (0); prenatal replacement (1).

  43. (43)

    Orientation of left and right molar series: parallel to each other (0); anteriorly convergent (1).

  44. (44)

    Cement in late ontogenetic stages: absent (0); present (1).

  45. (45)

    Cement in young-adult ontogenetic stages: absent (0); present (1).

  46. (46)

    Cement in juvenile ontogenetic stages: absent (0); present (1).

  47. (47)

    Lobes in p4: two incipient lobes (0); two well-developed lobes, but lacking an anterior projection; (1) two lobes and one incipient anterior projection that is not separated from the anterior lobe by an interprismatic furrow (2); two lobes and one developed anterior projection separated from the anterior lobe by a well-developed interprismatic furrow (3); three lobes (4).

  48. (48)

    Distribution of enamel in molars: covering the entire crown (0); interrupted at the base of the lingual wall (1); interrupted at the base and the corner of the lingual wall (2); interrupted at the base and in two strips (3); interrupted along the entire labial wall of the upper molars (lingual of the lower molars) except for the flexus/ids opposite to the hyopflexus/id (4); interrupted along the entire lingual wall and anterolingual and posterolingual walls (5).

  49. (49)

    Fossettes/ids in late ontogenetic stages: present (0); absent (1).

  50. (50)

    Fossettes/ids in young-adult ontogenetic stages: present (0); absent (1).

  51. (51)

    Fossettes/ids in juvenile ontogenetic stages: present (0); absent (1).

  52. (52)

    Shape of the fossettes/ids: elongated (0); subcircular (1).

  53. (53)

    Number of lobes in P4: two (0); one (1).

  54. (54)

    Posterior projection of M3: absent (0); present (1).

  55. (55)

    Development of posterior projection of M3: incipient (0); developed (1); M3 with multiple laminae (2).

  56. (56)

    Mesofossettid in young-adult stages: present (0); absent (1).

  57. (57)

    Fusion of the mesolophid with the anterolophid (metalophulid II and metalophulid I respectively sensu Marivaux et al. 2004): no (0); yes (1). (Kramarz 2005: character 15).

  58. (58)

    Reduction of the mesolophid (metalophulid II sensu Marivaux et al. 2004): complete (0), reduced (1). (Kramarz 2005: character 16).

  59. (59)

    Mesoflexid remains opened: no (0); yes (1). (Kramarz 2005: character 17).

  60. (60)

    Size of oval foramen: small (1); large (0). (Quintana 1998: character 1)

  61. (61)

    Apex of mesopterygoid fossa with respect to M2: level with M2 (0); apex in front of M2 (1). (Quintana 1998: character 2)

  62. (62)

    Articulation of nasals with respect to premaxillae: nasals articulate with premaxillae throughout their length (0); anterior half of nasals do not articulate with premaxillae (1). (Quintana 1998: character 6)

  63. (63)

    Interorbital width: longer or equal to braincase (0); shorter than braincase (1). (Quintana 1998: character 14)

  64. (64)

    Shape of frontals: markedly convex posteriorly (1); not convex (0). (Quintana 1998: character 15; Ubilla et al. 1999: character 14)

  65. (65)

    Extension of pterygoids: short (0); long and oriented posteriorly (1). (Quintana 1998: character 17).

  66. (66)

    Pterygoids: free (0); fused to the auditory bullae (1). (Quintana 1998: character 18).

  67. (67)

    Shape of the margins of the incisive foramina: with rounded margins (0); with straight and parallel margins (1). (Quintana 1998: character 21; Ubilla et al. 1999: character 6).

  68. (68)

    Position of the posterior margin of the upper diastema: not vertical (0); vertical (1). (Quintana 1998: character 23; Ubilla et al. 1999: character 23).

  69. (69)

    Shape of palate: concave (0); plane (1). (Quintana 1998: character 24; Ubilla et al. 1999: character 12)

  70. (70)

    Upper zygomatic process of the maxilla: not extended as plate-shaped in the rostrum (0); plate-shaped (1). (Quintana 1998: character 25; Ubilla et al. 1999: character 24)

  71. (71)

    Shape of upper margin of the infraorbital foramen: not straight (0); with straight upper margin (1). (Quintana 1998: character 26; Ubilla et al. 1999: character 5).

  72. (72)

    Incisive foramina: not reduced (0); reduced (1). (Quintana 1998: character 27).

  73. (73)

    Jugular and carotid foramina: fused (0); not fused (1). (Quintana 1998: character 28; Ubilla et al. 1999: character 36).

  74. (74)

    Position of lacrimal: totally interposed between maxilla and premaxilla (0); partially interposed between maxilla and premaxilla (1). (Quintana 1998: character 32; Ubilla et al. 1999: character 8).

  75. (75)

    Postfrontal spinous process of the jugal: absent (0); present (1). (Quintana 1998: character 33; Ubilla et al. 1999: character 31).

  76. (76)

    Orbital foramen: fused to the foramen rotundum (0); separated from the foramen rotundum (1). (Quintana 1998: character 34).

  77. (77)

    Position of upper incisors: orthodont (0); inclined (1). (Quintana 1998: character 35).

  78. (78)

    Enamel of upper and lower incisors: uncolored (0); with color (1). (Quintana 1998: character 36; Ubilla et al. 1999: character 13).

  79. (79)

    Shape of nasals: not anteriorly vaulted (0); greatly vaulted anteriorly (1). (Quintana 1998: character 38; Ubilla et al. 1999: character 3).

  80. (80)

    Shape of palatines: without posterior flat expansion (0); with posterior flat expansion (1). (Quintana 1998: character 39; Ubilla et al. 1999: character 11).

  81. (81)

    Position of parietals: in the same plane with respect to the nasals (0); in different plane with respect to the nasals (1). (Quintana 1998: character 40; Ubilla et al. 1999: character 25).

  82. (82)

    Position of the occipital condyles: below the lower limit of the auditory bullae (0); above the lower limit of the auditory bullae (1). (Quintana 1998: character 41; Ubilla et al. 1999: character 27).

  83. (83)

    Supraorbital foramen or notch: conspicuous (0); absent (1). (Quintana 1998: character 42).

  84. (84)

    Position of P4 alveolar prominence: near to the nasolacrimal foramen margin (0); far anterior to this margin (1). (Ubilla et al. 1999: character 4).

  85. (85)

    Masseteric fossa of the zygomatic arch: shallow and not well delimited (0); deep and well delimited (1). (Ubilla et al. 1999: character 9).

  86. (86)

    Position of the boundary between the mastoid and paraoccipital processes: at the same level or above the external auditory meatus (0); beneath the external auditory meatus (1). (Ubilla et al. 1999: character 15).

  87. (87)

    Shape of the squamosal process: straight (0); curved (1). (Ubilla et al. 1999: character 18).

  88. (88)

    Shape of the external auditory meatus: long and tube-shaped (0); short (1). (Ubilla et al. 1999: character 19).

  89. (89)

    Posterior apophysis of the squamosal: partially covering the epitympanic sinus (0); completely covering the epitympanic sinus (1). (Vucetich 1975, 1984).

Appendix 2

Table 3 Character-taxon matrix used for phylogenetic analysis. Characters between brackets represent polymorphic or uncertain scorings. Data matrix modified of Pérez 2010b
Full size table

Appendix 3. Analyzed Specimens of Taxa Used in Phylogenetic Analysis and Comparison

List of specimens of ingroup.

Asteromys punctus—MACN A 52-110 (holotype), R mandibular fragment with i, p4-m3; MLP 59-II-26-97, L mandibular fragment with i, dp4, p4-m3. Chubutomys simpsoni—AMNH 29557 (holotype), L mandibular fragment with m2-m3. Chubutomys leucoreios—MPEF-PV 1153 (holotype), L mandibular fragment with p4-m3. Luantus initialis—MACN A 52-164 (lectotype), L mandibular fragment with i, p4-m2; MPEF-PV 6056, R maxillary fragment with P4-M2; MPEF-PV 7979, R upper molar; MLP 85-VII-3-7, R lower molar; MLP 93-XI-18-28, L lower molar. Luantus minor—MPEF-PV 5007 (holotype), R mandibular fragment with m1-m2; MPEF-PV 1154a, L lower molar; MPEF-PV 5028, R M3; MPEF-PV 1154b, R upper molar. Luantus propheticus—MACN A 2018 (holotype), R mandibular fragment with p4-m3. And see Appendix in Kramarz (2006). Luantus toldensis—MACN Pv SC2574 (holotype), R lower molar. And see Appendix in Kramarz (2006). Phanomys mixtus—MACN A 2022 (neosintype): MACN A 11-302, R maxillary fragment with P4-M2; MLP 15-341, L maxillary fragment with P4-M2; MLP 15-217a, R mandibular fragment with m2-m3; MLP 91-II-25-3, R mandibular fragment with m2-m3 and L mandibular fragment with p4-m2. And see Appendix in Kramarz (2006). Phanomys vetulus—P4 superior isolated and M superior isolated (iconotype; Fig. 25, Ameghino 1891). Eocardia montana—(neosintype). MACN A 336, L mandibular fragment with i, p4-m2; MACN A 337, R mandibular fragment with p4-m2; MACN A 338, L maxillary fragment with M1-M2; MACN A 339 L mandibular fragment with p4; MACN A 340, L mandibular fragment with p4-m3 (holotype of Eocardia perforata); MACN A 446, R mandibular fragment with i, p4-m2 (holotype of Dicardia maxima); MACN A 4475 (holotype of Tricardia divisa); YPMPU 15323, L mandibular fragment with i, p4-m2 (holotype of Eocardia. petersoni); MLP 15-98, L mandibular fragment with m2-m3; MLP 15-112, L mandibular fragment with p4-m3; MLP 63-XII-19-44, L mandibular fragment with i, p4-m1; MLP 63-XII-19-46, R mandibular fragment with i, p4-m2; MLP 63-XII-19-47, R mandibular fragment with p4-m2; MLP 63-XII-19-49, R mandibular fragment with p4-m3; MLP 63-XII-19-51 R mandibular fragment with i, p4-m1; MLP 63-XII-19-54, R maxillary fragment with M1-M2; MLP 63-XII-19-56, L maxillary fragment with P4-M2; MLP 63-XII-19-71, R mandibular fragment with m1-m2; MLP 67-V-23-3, R mandibular fragment with m1-m3; MLP 68-I-16-5, L mandibular fragment with i, p4-m3; MACN A 341, L mandibular fragment with m1-m2; MACN A 2009, four M3 isolated; MACN A 2015 L mandibular fragment with i, p4-m3 and R mandibular fragment with i, p4-m2; MACN A 4455, L mandibular fragment with m1-m3; MACN A 4456, L mandibular fragment with p4-m3; MACN A 4457, R mandibular fragment with m2-m3; MACN A 4503, R mandibular fragment with p4-m1; MLP 15-325, R mandibular fragment with p4-m3; MLP 15-326, R mandibular fragment with m1-m2; MLP 15-327, L mandibular fragment with p4-m1; MLP 15-328, R mandibular fragment with m1; MPEF-PV 1349, L mandibular fragment with i, m2-m3; MACN A 10204, R mandibular fragment with dp4-m2; MACN A 10205, R mandibular fragment with dp4-m2; MACN A 10206a, R mandibular fragment with p4-m1; MACN A 10206b, R mandibular fragment with dp4-m1; MACN A 10207/8, Rdp4, Ldp4 and LM3; MACN A 10215, R mandibular fragment with p4 and m1; MACN A 10216, L mandibular fragment with p4-m1; MACN A 10227, L mandibular fragment with p4-m1; MACN A 10931, molar; MACN A 4483, L maxillary fragment with P4-M3; MLP 90.III.5.15, R mandibular fragment with m1-m2; MLP 90.III.5.37, L mandibular fragment with p4-m1; MLP 90.III.5.12, L mandibular fragment with dp4-m1; MLP, 91.I.10.8, three molars; MLP 91.I.10.1, R mandibular fragment with m1-m2; AMNH 97683, R mandibular fragment with m1-m3; AMNH 97733, L mandibular fragment with dp4-m1; AMNH 97748, L mandibular fragment with i, p4-m3; AMNH 99307, L mandibular fragment with m1; AMNH 99313, R mandibular fragment with p4-m1; R maxillary fragment with M2-M3; AMNH 9590, R mandibular fragment with p4-m3 and L mandibular fragment with i, p4-m3; AMNH 97656, m2 and m3; AMNH 97667, R mandibular fragment with P4-M2 and L P4-M1; AMNH 94594, R maxillary fragment with P4-M3 and L P4-M3; YPMPU 15058, R mandibular fragment with i, p4-m1; YPMPU 15574, R and L mandibular fragment with incisors and L p4-m3; YPMPU 15583, R mandibular fragment with m2-m3; YPM PU 15372, R mandibular fragment with i, p4-m3; YPMPU 15635, L mandibular fragment with p4-m2; YPMPU 15874, maxillary fragment with L and R P4-M1 and L M2. Eocardia fissa—R mandibular fragment with i, p4-m3 (iconotype; Ameghino 1891: fig. 24). MACN A 4468, R mandibular fragment with p4-m1; MACN A 10407, R mandibular fragment with p4-m3; MACN A 4461, L mandibular fragment with p4-m1; MACN A 4463 R mandibular fragment with i, p4-m3; MACN A 4458, L mandibular fragment with p4-m2; MACN A R mandibular fragment with p4-m3; MACN A 2009, 15 M3; MACN A 2009, two molars; MACN A 10211, skull fragment with two molariforms series and L incisor; MACN A 10957a, palate fragment with two molar series; MACN A 10957b, maxillary fragment with two molar series; MACN A 10957c, maxillary fragment with two molar series; MACN A 10957d, maxillary fragment with two molar series; MACN A 10931, R mandibular fragment with m1-m2; MACN A 10931, R mandibular fragment with m1; MACN A 10931, upper molar, MACN A 10931, five molars; MACN A 10931, 40 molars; MACN A 10210, R mandibular fragment with p4-m3; MACN A 10210, maxillary fragment with L P4-M3 and R M1; MACN A 4485, maxillary fragment with L P4-M3 and R M2-M3; MACN A 10729, maxillary fragment with R P4-M2; MACN A 10203, skull fragment with R I, M1-M3; MACN A 4469, R mandibular fragment with p4-m1; MACN A 4470, R mandibular fragment with p4; MACN A 4471, L mandibular fragment with p4-m1; MACN A 4489, maxillary fragment with R P4-M3 and L M1-M3; MACN A 10212, maxillary fragment with two molar series; MACN A 4486, maxillary fragment with two molar series; MACN A 10957, L mandibular fragment with i, p4-m2; MACN A 10957, R mandibular fragment with p4-m1; MACN A 10957, L mandibular fragment with p4-m2; MACN A 10957, L mandibular fragment with m1-m2; MACN A 10957, R mandibular fragment with p4-m2; MACN A 10957, L mandibular fragment with p4-m2; MACN A 10957, R mandibular fragment with p4-m2; MACN A 10957, L mandibular fragment with p4-m1; MACN A 10957, maxillary fragment with L P4-M2; MACN A 4490, upper molar; MACN A 4493, maxillary fragment with L P4; MACN A 4497, maxillary fragment with L P4-M2; MACN A 4498, maxillary fragment with R P4-M2; MACN A 4499, maxillary fragment with L P4-M1 and R P4-M2; MPEF-PV 1507, R mandibular fragment with i, p4-m3; MPEF-PV 1659, maxillary fragment with two molar series; MPEF-PV 1621, fragment of skull with two dental series; MLP 15-97, L mandibular fragment with m1-m2; MLP 15-313, R mandibular fragment with i, p4-m2; MLP 15-316, maxillary fragment with L P4-M2; MLP 15-291, maxillary fragment with two molar series; MLP 15-394, L mandibular fragment with p4-m2; MLP 63-XII-19-70 L mandibular fragment with p4-m2; MACN A 2016, R mandibular fragment with p4-m2; MACN A 10214, L mandibular fragment with p4-m3; YPMPU 15010, fragment of skull with two dental series; YPMPU 15022, maxillary fragment with L P4-M3; YPMPU 15463, R mandibular fragment with p4-m2 and maxillary fragment with two molar series; YPMPU 15380, R mandibular fragment with p4-m2; YPMPU 15327, maxillary fragment with L and R M1-M3; YPMPU 15276, maxillary with two molar series. Eocardia excavata—MACN A 4472 (holotype) p4-m2; MACN A 107, L mandibular fragment with i, p4-m2; MACN A 4476 (holotype Tricardia gracilis), L mandibular fragment with p4-m2; MACN A 4467 (holotype Dicardia proxima), R mandibular fragment with i, p4-m3; MACN-A 10226, R mandibular fragment with p4-m3; MACN A 10219, L mandibular fragment with p4-m2; MACN A 10222, R mandibular fragment with m1-m2; MACN-A 10223, R mandibular fragment with p4-m2; MACN A 10225, L mandibular fragment with p4-m2; MACN A 4470, R mandibular fragment with p4; MACN A 4471, L mandibular fragment with p4-m1; MACN A 4460, R mandibular fragment with p4-m1; MLP 15-302, R mandibular fragment with p4-m3; MLP 15-114, R mandibular fragment with p4-m2; MLP 15-329, L mandibular fragment with m1-m2; MLP 15-383, L mandibular fragment with p4-m2; MLP 63-XII-19-48, R mandibular fragment with m1; MLP 15-303, maxillary fragment with R M2-M3; MACN A 4459, L mandibular fragment with p4-m1; MACN-A 10209, maxillary fragment with two molar series; MACN A 4454, skull; MACN A 10931, three molars; MACN A 10931, five upper molars and three lower molars; MACN A 2008, L mandibular fragment with; MACN A 2009, L mandibular fragment with p4-m1; MACN A 2009, 11 M3; MACN A 2011, R mandibular fragment with i, m1; MACN A 2012, L mandibular fragment with p4; MACN A 425-434, 10 molars; MACN A 2020, R mandibular fragment with M2-M3; MACN A 2020, two upper molars; MACN A 342, L mandibular fragment with p4-m1; MACN A 343, L mandibular fragment with m1-m2; MACN A 4500, maxillary fragment with R P4-M3; MACN A 4501, maxillary fragment with R P4-M2; MACN A 10957, L mandibular fragment with p4-m3; MACN A 10957, R mandibular fragment with p4-m1; MACN A 10957, R mandibular fragment with p4-m2; MACN A 10957, R mandibular fragment with p4-m1; MACN A 10957, L mandibular fragment with m2-m3; MACN A 10220, L mandibular fragment with m1-m2; MACN A 4496, L mandibular fragment with m2-m3; MACN A 10213, p4-m1; MACN A 10221, R mandibular fragment with p4-m3; AMNH 97665, R mandibular fragment with p4-m3; AMNH 97682, R mandibular fragment with p4-m1; AMNH 99308, R mandibular fragment with m2-m3; AMNH 99309, L mandibular fragment with m1-m2; AMNH 99310, R mandibular fragment with p4-m1; AMNH 99311, R mandibular fragment with p4-m1; AMNH 99312, L mandibular fragment with p4-m2; YPMPU 15126, L mandibular fragment with m1-m3; YPMPU 15205, maxillary fragment with R and L M1-M2 and R mandibular fragment with i, p4-m1; YPMPU 15326, R mandibular fragment with m1-m3; YPMPU 15383, fragment of skull with R DP4-M3 and L DP4-M2; YPMPU 15550, R mandibular fragment with i, p4-m2; YPMPU 15810, maxillary fragment with R M1-M2; YPMPU 15977, R mandibular fragment with m2-m3; YPMPU 15054, maxillary fragment with R P4-M3; YPMPU 15621, maxillary fragment with R and L P4-M3; AMNH 99330, maxillary fragment with R M1-M3. Eocardia robusta—MLP 15-414 (holotype), skull with two molar series; MLP 74-II-1-7, maxillary fragment with L DP4-M3; MLP 15-417, L mandibular fragment with i, p4-m3; MLP 91-IX-2-93, skull with R P4-M3 and L P4-M2; MLP 92-V-10-3, L mandibular fragment with m1-m2; MLP 91-IX-2-81, R mandibular fragment with i, p4-m3; MLP 91-V-1-89, R mandibular fragment with m1-m3; MLP 92-V-10-67, L mandibular fragment with p4-m2; MLP 92-V-10-68, R mandibular fragment with m2-m3; MLP 92-V-10-70, R mandibular fragment with p4-m2; MLP 92-V-10-71, L mandibular fragment with m1 and m2 isolated; MLP 92-V-10-73, R mandibular fragment with m3; MLP 92-V-10-74, R mandibular fragment with incisor; MLP 92-V-10-75, maxillary fragment of; MLP 91-V-1-73, R maxillary fragment with DP4?-M2; MLP 91-V-1-74, R mandibular fragment with p4-m1; MLP 91-V-1-75, L mandibular fragment with m2-m3; MLP 92-V-10-69, R mandibular fragment with p4-m1; MLP 91-IX-2-1, L mandibular fragment with p4-m1; MLP 74-II-1-34, maxillary fragment with M1-M3; MJHG 76-III-1-1, rostral region with L dental series and two incisors. Eocardia robertoi—MLP 80-VII-1-1 (Holotype), maxillary fragment L P4-M3 and R M1-M3. Matiamys elegans—MACN Pv 14565 (holotype), skull with two dental series; MLP 90-XII-25-I, maxillary fragment with L DP4-M3 and R P4-M3. Schistomys erro—MLP 68-I-16-7, maxillary fragment with L I, P4-M3, R I, P4-M1; MACN A 4479 (holotype of Schistomys crassus), skull with two dental series; MACN A 2019 (holotype of Procardia elliptica), R mandibular fragment with i, p4-m3; MACN A 4480b, maxillary fragment with L and R P4; MLP 63-XII-19-50, R maxillary fragment with P4-M3; MLP 63-XII-19-55, L maxillary fragment with P4-M2; MLP 63-XII-19-58, L maxillary fragment with M1-M3; YPMPU 15648, skull and mandible; MLP 15-330, R maxillary fragment with M1-M3; YPMPU 15420, fragment of skull with R dental series; YPMPU 15620, fragment of skull with L P4-M3 and R M1-M3; YPMPU 15587, fragment of skull with R P4-M2; AMNH 9539, fragment of skull with R M1-M3 and L M3. Schistomys rollinsii—YPM 15969 [SIC] = YPMPU 15959 (holotype), skull with two molariforms series. Guiomys unica —MPEF-PV 3504 (Holotype), R mandibular fragment of with p4-m3; MPEF-PV 3505, R mandibular fragment; MPEF- PV 3506, L mandibular fragment with p4-m3; MPEF-PV 3508, L mandibular fragment with p4-m2; MPEF-PV 3513, L mandibular fragment with p4-m2; MPEF-PV 3514, L mandibular fragment with p4-m2; MPEF-PV 3512, R mandibular fragment with m1-m2; MPEF-PV 3519, R mandibular fragment with m1-m2; MPEF-PV 3524, R mandibular fragment with p4-m1; MPEF-PV 3526, R mandibular fragment with p4-m1; MPEF-PV 3529, R mandibular fragment with p4-m1; MPEF-PV 3527, L mandibular fragment with p4-m1; MLP 91-IX-4-3, L mandibular fragment with p4-m1; MPEF-PV 3533, maxillary fragment with L P4-M2 and R P4-M1; MPEF-PV 3534, maxillary fragment with R P4-M1 and M3; MPEF-PV 3535, R maxillary fragment with M2-M3; MPEF-PV 3537, R maxillary fragment with M2-M3; MPEF-PV 3536, R maxillary fragment with M2-M3; MPEF-PV 3538, L maxillary fragment with M1-M2; MPEF-PV 3539, L maxillary fragment with M3; MPEF-PV 3540, L maxillary fragment with P4; MPEF-PV 3541, L maxillary fragment with P4; MPEF-PV 3542, R maxillary fragment with P4; MPEF-PV 3543, R maxillary fragment with M1; MLP 91-IX-4-2, R mandibular fragment with p4-m2; MLP 91-IX-4-1, maxillary fragment with both dental series. Prodolichotis pridiana—skull and mandible have been scored from the literature (Fields 1957: holotype UCMP 38761). Orthomyctera chapadmalense—MLP 15-229 (holotype), skull and mandible. Dolicavia minuscula—MLP 34.V.10.10, skull; MLP 91.IV.5.333, skull and mandible; MLP 95.IX.4.1 L mandibular fragment with p4-m2; MPEF-PV 1398a, fragment of skull with I, R P4-M3 and L P4-M1; MPEF-PV 1398b, R mandibular fragment with p4-m3, L p4 and incisors.; MPEF-PV 1398c, maxillary fragment with L M2-M3 and R M1-M2; MPEF-PV 1398d, maxillary fragment with L P4-M2; MPEF-PV 1398e, L M2-M3; AMNH 98823, L mandibular fragment with I, p4-m2. Cardiomys cavinus— MLP 55.IV.28.11, skull; MLP 76.VI.12.18, L mandibular fragment with p4-m1. Phugatherium novum—Fcs 92-5-15/1, skull; Fcs 92-5-15/2, skull; Fcs 92-5-15/3, R mandibular fragment with I, p4-m2. Dolichotis salinicola—MLP 672, skull and mandible; MLP 673, skull and mandible. Dolichotis patagonum—MLP 640, skull and mandible; MPEF-PV 41, skull and mandible; MPEF-PV 42, skull and mandible. Cavia aperea—MLP 1.XI.95.7, skull and mandible; MLP 12.II.92.4, skull and mandible; MMPMa 2239, skull and mandible; MMPMa 2318, skull and mandible; MMPMa 2319, skull and mandible; MMPMa 2320, skull and mandible; MMPMa 2322, skull and mandible; MMPMa 2324, skull and mandible; MMPMa 2367, skull and mandible; MMPMa 3233, skull and mandible; MMPMa 144, skull and mandible; MMPMa 4099, skull and mandible. Galea musteloides—MLP 738, skull and mandible; MLP 14.IX.98.4, skull and mandible; MMPMa 2698, skull and mandible. Microcavia australis— MLP 518, skull and mandible; MLP 684(1), skull and mandible; MLP 684(2), skull and mandible; MLP 684(3), skull and mandible; MLP 684(5), skull and mandible; MLP 684(11), skull and mandible; MLP 684(12), skull and mandible; MLP 684(13), skull and mandible; MLP 684(14), skull and mandible; MLP 684(18), skull and mandible; MLP 13.IX.95.7, skull and mandible. Kerodon rupestris—MMPMa 1257, skull and mandible; MMPMa 1470, skull and mandible. Hydrochoerus hydrochoeris— MLP 1.XII.008, skull and mandible; MLP 5.V.99.1, skull and mandible; MLP 4.X.94.5, skull and mandible; MLP 8.X.97.3, skull.

List of specimens of outgroup.

Neoreomys australis—MPEF-PV 1651, skull; MPEF-PV 1636, L mandibular fragment with i, p4-m3; MPEF-PV 1348, R mandibular fragment with p4-m3; MPEF-PV 1346, R mandibular fragment with p4-m2; MPEF-PV 1727, L mandibular fragment with m1-m2; MPEF-PV 1726, R mandibular fragment with m1-m3; MPEF-PV 1725, R mandibular fragment with I and p4. Dasyprocta azarae— MLP 1420, skull and mandible; MLP 1421, skull and mandible; MLP 05.IX.97.02, skull and mandible. Cuniculus paca—MLP 24.IX.01.24, skull and mandible; MLP 1105, skull and mandible. Proechimys poliopus—MLP 22.II.00.7, skull and mandible; MLP 22.II.00.8, skull and mandible.

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Pérez, M.E., Vucetich, M.G. A New Extinct Genus of Cavioidea (Rodentia, Hystricognathi) from the Miocene of Patagonia (Argentina) and the Evolution of Cavioid Mandibular Morphology. J Mammal Evol 18, 163–183 (2011). https://doi.org/10.1007/s10914-011-9154-1

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