Patriarchus palmidens Ameghino, 1889

Fernández, Mercedes, Fernicola, Juan Carlos, Cerdeño, Esperanza & Reguero, Marcelo A., 2018, Identification of type materials of the species of Protypotherium Ameghino, 1885 and Patriarchus Ameghino, 1889 (Notoungulata: Interatheriidae) erected by Florentino Ameghino, Zootaxa 4387 (3), pp. 473-498 : 487-490

Patriarchus palmidens Ameghino, 1889

Holotype. MACN-A 9651a ( Figs. 3 A–C ), mandibular symphysis with right i1 –p1 and left i1–2 and the alveolus of i3.

Diagnosis ( Ameghino 1889: 481). “ Es la única especie de este género que conozco hasta ahora; y a juzgar por la parte anterior de la mandíbula, tuvo una talla bastante mayor que el Protypotherium antiquum . La sínfisis es muy comprimida lateralmente y sumamente angosta adelante, como que hasta el mismo par de incisivos anteriores están colocados no adelante en sentido transversal, según es de regla en la generalidad de los mamíferos, sino a los lados, en la misma línea longitudinal que todo el resto de la dentadura, lo que le da a esta región un aspecto completamente particular. Cada uno de estos incisivos tiene una corona cuyo diámetro anteroposterior aumenta desde la base a la cúspide, siendo ella sumamente comprimida en sentido transversal, con la cara interna bilobada por un surco perpendicular angosto y profundo en su parte superior, pero que se pierde hacia la base del diente y con la cara externa lisa y convexa. El canino tiene absolutamente la misma forma que los incisivos. Estos cuatro dientes están implantados en la mandíbula inclinados oblicuamente adelante de una manera cada vez más acentuada a partir del canino hasta los incisivos internos, los que se dirigen hacia adelante de una manera casi horizontal. Cada uno de estos dientes tiene una corona de 0m0 0 4 a 0m0 0 45 de diámetro anteroposterior, por 0m0 0 1 a 0m0 0 15 de diámetro transverso. El p.1, está implantado verticalmente, con los dos surcos opuestos colocados en los dos últimos tercios de cada cara, angostos y poco profundos. El lóbulo anterior es mucho mayor, más ancho y de forma elíptica; el lóbulo posterior mucho más pequeño, es también más angosto y de forma casi circular. Este diente tiene 0m0 0 45 de diámetro anteroposterior por 0m0 0 23 de diámetro transverso. Los tres incisivos, el canino y el primer premolar ocupan juntos en línea recta un espacio longitudinal de 25 milímetros. La sínfisis tiene 10 milímetros de largo y es profundamente excavada en su cara interna ”.

English translation. This is the only species of this genus so far known. Based on the size of the anterior part of the mandible, it was considerably larger than Protypotherium antiquum . The mandibular symphysis is very laterally compressed and notably narrow anteriorly, so that the anterior incisors are not transversally positioned as generally seen in mammals, but laterally in the same longitudinal line as the remaining teeth, a fact that gives a completely particular aspect to this region. Each incisor exhibits its anteroposterior diameter increasing from the base to the tip, the latter highly compressed transversely, with its internal face bilobed by means of a narrow and deep perpendicular groove that disappears towards the base, and with its external face smooth and convex. The canine has the same morphology as the incisors. These four teeth are obliquely implanted in the jaw obliquely inclined forward, mainly the internal incisors that are nearly horizontally placed. The crown of each of these teeth has 0.004 m to 0.0045 m of anteroposterior diameter and 0.001 m to 0.0015 m of transverse diameter. The p1 is vertically implanted, with two opposite narrow and shallow grooves placed in the last two thirds of each face. The anterior lobe is much larger, wider and elliptical; the posterior lobe is much smaller, also narrow and almost circular. This tooth has 0.0045 m of anteroposterior diameter and 0.0023 m of transverse diameter. The three incisors, the canine and the first premolar occupy together, in a straight line, a length of 25 mm. The symphysis is 10 mm long and is deeply excavated internally.

Comments. Ameghino (1889: 481) founded this taxon based only on a mandibular symphysis that was illustrated in his Atlas ( Ameghino 1889, plate 15: figs. 2–3) and herein reproduced ( Figs. 3 D–F ). According to Ameghino’s catalogue, MACN-A 37 (a complete skull), MACN-A 38 (a right mandibular branch associated to MACN-A 37), and MACN-A 4045 (a right mandibular ramus) are the type specimens of this species. Instead, after Mones (1986), only MACN-A 4045 is the type material. Nevertheless, none of these specimens matches the original description or the illustrated symphysis ( Ameghino 1889) and, as a result, they are discarded as the type of the species. In Ameghino’s catalogue there are 22 other specimens assigned to Pa. palmidens , nine of which are lost. Among the remaining, a symphysis located within the lot MACN-A 9651, and herein differentiated as MACN-A 9651a, matches the original description and the illustrated symphysis ( Ameghino 1889). Consequently, it is recognised as the holotype of Pa. palmidens . This lot includes other five fragmented mandibles (identified by us as MACN-A 9651b to MACN-A 9651f) that belong to different individuals. These specimens are discarded as part of the type series because, on the one hand, Ameghino (1889) used an unique specimen to erect the species and, on the other hand, none of them presents anterior dentition, but cheek teeth which would have been described by Ameghino in case he had had these teeth at hand.

Chronological and geographical distribution of the type specimen. “Notohippidian” ( Ameghino 1900 – 1902, 1906), Santacrucian SALMA, Santa Cruz Province.

Figures

FIGURE 3. Patriarchus palmidens, holotype MACN-A 9651a, mandibular symphysis with right i1–p1 and left i1–2 and the alveolus of i3, in labial (A), occlusal (B) and antero-labial (C) views; reproductions of figures 2 (D), 2a (E) and 2b (F) from Ameghino (1889, plate 15). Patriarchus furculosus, syntype MACN-A 3970, left maxillary fragment with P2–M3, in occlusal view (G); syntype MACN-A 3972, right mandibular fragment with p2–m3, in occlusal view (H); syntype MACN-A 3977, incomplete skull, dorsal view (I). Patriarchus distortus, holotype MACN-A 9634 to MACN-A 9638: MACN-A 9634, skull, ventral (J)and dorsal (K) views; MACN-A 9636, proximal epiphysis of right femur, in anterior view (L); MACN-A 9637 and MACN-A9638, proximal epiphyses of right tibia and fibula,articulated with the distal epiphysis of right femur, in lateral view (M). Patriarchus rectus, holotype MACN-A 4005, right maxillary fragment (vertically rotated) with alveolus of C and series P1–M3, in occlusal view (N); holotype MACN-A 4006, left maxillary fragment (vertically rotated) with M1–3, in occlusal view (O); holotype MACN-A 4007, mandibular fragment with incomplete symphysis, broken alveoli of left and right i1-2 and complete left i3–m3 series, in occlusal view (P). Patriarchus diastematus, holotypeMACN-A 4044, two maxillae with alveoli of C–P1 andright P2–M3 andleft P2–M2, in occlusal view (Q). Scale bar = 10 mm.