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FIG. 6 in L'apport du registre paléogène d'Amazonie sur la diversification initiale des Caviomorpha (Hystricognathi, Rodentia): implications phylogénétiques, macroévolutives et paléobiogéographiques

FIG. 6. — Consensus strict de l'AG1 (Fig. 5) et indices de Bremer aux noeuds. Les taxons en gras sont les espèces découvertes dans le Paléogène de Contamana (Éocène et Oligocène) et à Tarapoto/Shapaja. Le code couleur est le même que celui de la Figure 3.

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FIG. 3 in L'apport du registre paléogène d'Amazonie sur la diversification initiale des Caviomorpha (Hystricognathi, Rodentia): implications phylogénétiques, macroévolutives et paléobiogéographiques

FIG. 3. — Arbre de contrainte employé pour les AG1-AG9, basé sur des données moléculaires. Modifié d'après Upham & Patterson (2015: 77, fig. 3). Les quatre super-familles de caviomorphes sont différenciées par des couleurs: Cavioidea (rouge), Chinchilloidea (bleu), Erehizontoidea (orange) et Octodontoidea (violet).

FIG. 2 in Two New Taxa (Caviomorpha, Rodentia) from the Early Oligocene Tinguiririca Fauna (Chile)

FIG. 2. Location map; Tinguiririca River valley, Termas del Flaco, Chile (modified from Wyss et al., 1994).

FIG. 1 in Two New Taxa (Caviomorpha, Rodentia) from the Early Oligocene Tinguiririca Fauna (Chile)

FIG. 1. The transitional Eocene-Oligocene portion of the SALMA sequence (based on Flynn and Swisher, 1995; as modified by Croft et al., 2008).

FIG. 6 in Two New Taxa (Caviomorpha, Rodentia) from the Early Oligocene Tinguiririca Fauna (Chile)

FIG. 6. (A) Scanning electron micrograph (from Vucetich, 1989), and (B) line drawing of right p4–m2 of Eoviscaccia boliviana MNHN BLV 158 (MNHN(P)). (C–F) Line drawings of the lower dentition of Eoviscaccia australis, (C) MACN CH 1883 (left m1 or m2); (D) MCN CH 1883 (left m1 or m2); (E) MACN CH 1877 (left p4); and (F) MACN CH 1878 (right p4) (after Kramarz, 2001). Multiple teeth of Eoviscaccia australis are shown to illustrate the variable presence of anterofossettids on p4 and shape variability of teeth presumably from the same locus. Abbreviations: Al, anterior lobe; Atfd, anterofossettid; Hfxd, hypoflexid; Pl, posterior lobe. The angled arrow indicates anterior and lingual directions. Scale bars = 1 mm.

FIG. 5 in Two New Taxa (Caviomorpha, Rodentia) from the Early Oligocene Tinguiririca Fauna (Chile)

FIG. 5. Holotype of Eoviscaccia frassinettii (SGOPV 2935): (A) photograph and (B) line drawing of right p4–m3 in occlusal view; (C) photograph and (D) line drawing in labial view. Abbreviations: Al, anterior lobe; Atfd, anterofossettid, E, entoconid; H, hypoconid; Hfxd, hypoflexid; M, metaconid; P, protoconid; Pl, posterior lobe.

FIG. 3 in Two New Taxa (Caviomorpha, Rodentia) from the Early Oligocene Tinguiririca Fauna (Chile)

FIG. 3. The holotype of Andemys termasi, SGOPV 2933. Photographs (opposite page) in (A) lateral, and (B) occlusal views, with shaded drawings in (C) lateral, and (D) occlusal views. Line drawings (above) in (E) lateral and (F) occlusal views illustrating dental terminology used in text (following in part the nomenclature of Frailey and Campbell, 2004; Marivaux et al., 2004; Jenkins et al. 2005; Pérez, 2010); scale bar applies to A–D. Abbreviations: Atfd, anterofossettid; Atld, anterolophid; E, entoconid; Etlp, ectolophid; Hd, hypoconid; Hfxd, hypoflexid; Hlpd, hypolophid; Hpfd, hypofossettid; Ic, incisor; M, metaconid; Mc, masseter crest; Mf, mental foramen; Msfd, mesofossettid; Mtfd, metafossettid; Mtld, metalophid; nMpi, notch for the insertion of the tendon of the pars maxillomandibularis; Prd, protoconid; Psld, posterolophid; Rt, root; tMpi, tubercle for the insertion of the tendon of the pars maxillomandibularis. The angled arrow indicates anterior and lingual directions for occlusal views. Mandibular nomenclature follows Pérez (2010).

Fig. 29. Character trace for Character 4 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 29. Character trace for Character 4: Absence/presence of pessulus traversing stapedial obturator foramen (0, white; 1, black; vertical striping, equivocality). The wide distribution of the pessulus indicates that it is probably a primitive feature in ctenohystricans. It is highly likely that there are many other occurrences of pessuli in taxa not investigated here. ''Echimyidae'' here refers to Proechimys and Dactylomys only.

Fig. 28 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 28. Character traces for, on left, Character 2: Absence/presence of posttympanic foramen (0, white; 1, grey; 2, black; vertical striping, equivocality), and, on right, Character 3: Absence/presence of posttympanic canal (0, white; 1, black; vertical striping, equivocality). ''Canal present'' implies a visible, distinguishable structure. These characters are difficult to score in the absence of adequate comparative documentation on basicranial vasculature in ctenohystricans. In any case, the posttympanic foramen/canal complex (C2:1/ C2:2 + C3:1) broadly characterizes erethizontoids and chinchilloids but no other ctenohystricans, as far as is now known. The topology utilized in the diagrams favors the conclusion that the complex is a convergence between New World porcupines and chinchillas and their relatives. However, if the ramus posttympanicus is in fact related to the ramus posterior of the placental morphotype, then the resemblances are either primitive retentions or the result of de novo reacquistions.

Fig. 26 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 26. Theoretical interpretation of developmental interconnections among internal carotid, stapedial, and posterior auricular arteries in the ctenohystrican Bauplan, based on evidence discussed in the text. All diagrams are idealized for interpretative purposes; actual ontogeny is unknown. A, Hypothetical, fully elaborated arrangement, with proximally intact, medially positioned internal carotid providing blood to stapedial system exhibiting all three rami. Note anastomotic link or continuity between ramus posterior and posterior auricular via ramus posttympanicus. Note also small distributaries to stapedius muscle, inferred to be ramus inferior's primitive area of supply on basis of conditions in several tenrecs and eulipotyphlans Erinaceus and Solenodon (MacPhee, 1981). Whether, and to what degree, this arrangement is primitive for placentals more generally is not known. B, Example of a derived arterial arrangement, partly based on conditions in Amblyrhiza. For this taxon there is firm evidence only for the presence of the ramus posttympanicus; other parts of the internal carotid/stapedial system may have completely involuted by adult stage, or never formed. Blood supply to ramus posttympanicus here interpreted to have been retrograde, from posterior auricular. Pattern also applies to Dinomys, but may be inferred for Eumegamys and possibly certain other caviomorphs (including chinchillids and erethizontids).

Fig. 27. Character trace for Character 1 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 27. Character trace for Character 1: Absence/presence of tympanic fenestra (0, white; 1, grey; 2, black). With this topology, C1:2, isolated, suture-delimited aperture emerges as a diagnostic feature of extant Chinchillidae + Amblyrhiza, with no examples of convergence and with Dinomys and Eumegamys showing an alternative state. Placing Amblyhiza among octodontoids as a relative of Geocapromys, as some authors have suggested, seems unparsimonious in light of the fact that in this superfamily neither this state nor (with the exception of Octodon) the less derived state, C1:1, notch only (bridged or unbridged), is known to occur. In this and the following figure ''Echimyidae'' refers to the four representative taxa of spiny rats selected for study (Echimys, Proechimys, Lonchothrix, Dactylomys), which are invariant for the characters traced.

Fig. 24. Dasyprocta punctata AMNHM 41394 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 24. Dasyprocta punctata AMNHM 41394, left auditory region in lateral aspect. Both the notched and bridged conditions are widespread in caviomorphs, and represent different endpoints along the same ontogenetic pathway. In this young specimen the fenestra is widely open and plugged with meatal soft tissues (asterisk) that include, or are derived from, the fibrous membrane of the tympanic cavity (see MacPhee, 1981). Older specimens and adults show the same morphology, indicating that an ectotympanoectotympanic suture is never formed in this taxon.

Fig. 25 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 25. Development of the tympanic fenestra: inferred ontogenetic pathways for patterns culminating in C1:0, C1:1, and C:2 (top to bottom, then left to right). Cartoons are highly diagrammatic. Small arrows figuratively suggest major growth directions along meatal margin. Indifferent (youngest) stage, shown as primitive for all three character states, is based on known aspects of ectotympanic development in mammals (MacPhee, 1981). Intermediate and advanced stages partly based on these specimens: C1:0, Myocastor coypus AMNHM 80097, Bathyergus sp. AMNHM 168284; C1:1, Dasyprocta punctata AMNHM 41394, Hydrochoerus hydrochaeris AMNHM 98631; C1:2, Lagostomus maximus AMNHM 70222, Lagidium viscacia AMNHM 38981. For character state distribution in extant ctenohystricans, see appendix 2. In C1:0 (fenestra absent), ventral meatal margin (asterisk) may ossify more slowly than surrounding areas, but a proper tympanic fenestra is not normally present in adult. However, meatal innominate vessels may become enclosed where they cross the ossification front, leading to the definition of one or more small foramina. In C1:1 (tympanic fenestra present as a notch), the region of the bullar wall ventral to the presumptive meatus remains persistently unossified, leaving a narrow, distally expanded cleft. The cleft may stay in permanent communication with the true meatus, or a small tab of bone may grow out from one of the meatal borders and close it off (bridged condition). Fusion may follow, but occurs late in development. In C1:2 (tympanic fenestra isolated from meatus by suture), the anterior crus and body of the ectotympanic grow at a much faster pace than the posterior crus. Contact between the tips of the two crura occurs early, forming a true (ectotympano-ectotympanic) suture that separates the presumptive tympanic fenestra from the porus meatus. Meatus is typically greatly elongated in taxa displaying this pathway; at least in Lagostomus and close relatives, the anterior crus extends posteriorly to press against the mastoid region. Suture normally fused by late fetal or juvenile stage.

Fig. 23. Hydrochoerus hydrochaeris AMNHM 15468 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 23. Hydrochoerus hydrochaeris AMNHM 15468, left auditory region of a juvenile specimen; steropair view (with key) in oblique posterolateral aspect. Ventral floor of bulla partly removed (hatchure); dorsal portion of petrosal, inflated from epitympanic recess, forms prominent bulge externally (asterisk). Note widely communicating tympanic fenestra and external acoustic meatus via patent ventral cleft. In older animals the cleft is relatively narrower, thanks to continued bone growth, but generally remains open.

Fig. 15. Ctenodactylus gundi USNMM 325852 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 15. Ctenodactylus gundi USNMM 325852, right auditory region (rev.), in ventromedial aspect. The lateral wall is intact, with many perforations for meatal innominate vessels but no tympanic fenestra or posttympanic foramen. Also partly visible in this aspect is the unusual partial septum just inside the aperture of the external acoustic meatus, which forms a kind of ''secondary'' meatus (asterisk). It is not the crista tympani, which is situated more medially (and not visible in this aspect).

Fig. 1. Amblyrhiza inundata AAHS 95044 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 1. Amblyrhiza inundata AAHS 95044, left auditory region after removal of tympanic floor; stereopair view (with key, opposite page) in ventromedial aspect, showing tympanic collar and posttympanic canal.

Fig. 22. Myocastor coypus AMNHM 80097 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 22. Myocastor coypus AMNHM 80097, right (rev.) auditory region, before (A) and after (B, opposite page) removal of bullar floor; stereopair views (with key) in lateral and posteroventral aspects. In this juvenile nutria, the region of the lateral bullar wall beneath the external acoustic meatus is smooth and unnotched, suggesting that the ectotympanic develops in such a way that a tympanic fenestra is never developed as such. Barely visible in A is a foramen for a large meatal innominate vessel, the track of which scores the floor of the meatus just inside the porus (asterisk). Similar conditions are found in Capromyidae and Echimyidae, close relatives of Myocastor. Resemblances extend to middle ear with respect to conformation of cochlea, size of tympanic collar (slightly damaged in this specimen), and details of tympanic roof and epitympanic recess. Asterisk in B: sulcus crossing promontorium (? for tympanic nerve).

Fig. 19. Erethizon dorsatum AMNHM 20773 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 19. Erethizon dorsatum AMNHM 20773, (A) left and (B) right (rev.) isolated tympanopetrosals. A, oblique lateral aspect; B, stereopair in posteroventral aspect with bullar floor removed (posterior end toward top) and key on following page. Foramen visible on posterior bullar wall in A is the posttympanic foramen, through which, in B, a bristle (single asterisk) can be passed into a hemicanal (double asterisks). Hemicanal is inferred to have carried the ramus posttympanicus. The tympanic fenestra is absent in this species, as in other erethizontids, although meatal innominate foramina are conspicuous.

Fig. 5. Amblyrhiza inundata AMNHVP 11842 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 5. Amblyrhiza inundata AMNHVP 11842, left auditory region; stereopair view (with key, opposite page) in oblique lateral aspect. Asterisk, raised seam of ectotympano-ectotympanic suture continued onto floor of external acoustic meatus. Position of the posttympanic foramen is hidden by the projecting external acoustic canal. Paroccipital process is heavily pneumatized, in contrast to conditions in Eumegamys (see text).

Fig. 14. Dinomys branickii AMNHM 201638 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 14. Dinomys branickii AMNHM 201638; dissection of right side, oblique ventrolateral aspect. Structures superficial to the plane of the caudal belly of the digastric, including the gonial portion of the mandible, have been transected or removed to provide an unimpeded view of the auditory bulla and route of the superficial temporal/posterior auricular artery. (In the case of the mandible, cut extended into molar roots, as is evident here.) Tough meatal tissues occlude the tympanic fenestra; these were left in place so as not to damage the branch (asterisk) that gives off the ramus posttympanicus.