TAYASSUIDAE Palmer, 1897

Gasparini, Germán M., Dutra, Rodrigo Parisi, Perini, Fernando A., Croft, Darin A., Cozzuol, Mario A., Missagia, Rafaela V. & Lucas, Spencer G., 2021, On the Supposed Presence of Miocene Tayassuidae and Dromomerycinae (Mammalia, Cetartiodactyla) in South America, American Museum Novitates 2021 (3968), pp. 1-28 : 9-12

TAYASSUIDAE Palmer, 1897

REFERRED MATERIAL: LACM 154877 (holotype of Waldochoerus bassleri Frailey and Campbell, 2012 ), partial left mandibular ramus with p3–m3 ; USNM 513215 , partial right mandible with p4, m2–3 ; USNM 513222 , isolated right m1 ; USNM 513223 , partial right mandible with m1–m3 ; USNM 515225 , right palatal fragment, with P4–M3 (M2 damaged) .

IDENTITY OF Waldochoerus bassleri: For a better understanding of our analysis, we organize the morphological and morphometric remarks on every character considered by Frailey and Campbell (2012) in the following order: (1) diagnosis of the genus; (2) similarities of Waldochoerus to Dicotyles and differences from Tayassu ; (3) differences of Waldochoerus from Dicotyles ; and (4) diagnosis of the species Waldochoerus bassleri (figs. 3, 4).

According to these authors, Waldochoerus has the following diagnostic characters: mandible short and sturdy; high placement of mandibular condyle; and forward placement of mandibular condyle. All of these features characterize both extant genera of peccaries, Tayassu and Dicotyles ( Gasparini, 2007; Gasparini et al., 2011, 2014; Parisi Dutra et al., 2017). It is notable that mandibles in Dicotyles are smaller than those observed in Tayassu (see measurements in Gasparini, 2007; Gasparini et al., 2011, 2014).

According to Frailey and Campbell (2012), the new genus Waldochoerus is a medium- to small-sized peccary with a short snout that resembles Dicotyles and differs from Tayassu in having: posterior margin of ascending ramus below mandibular condyle straight or only slightly curved; dental crown pattern simple; labial conids with weak selenodonty; metaconid and hypoconid with reduced lophate connection; and quadrangular molar outline interrupted by deep indentations at transverse valleys.

In both genera, Dicotyles and Tayassu , the posterior margin of the vertical ramus extends posteriorly beyond the mandibular condyle, usually describing a pronounced curve in both genera. However, this outline is variable in both genera, and the posterior margin of the ascending ramus below the mandibular condyle can be a pronounced curve or slightly curved or even a straight line, as is present in W. bassleri .

The tooth crown morphology observed in the specimens from Peru is typically bunodont (fig. 3); the metaconid and hypoconid are well defined and contact each other via minor cuspids, as occurs in the bunodont morphology (the lophate connection mentioned by Frailey and Campbell does not correspond to this morphology). Lower molar teeth, in fact, have a rectangular outline in Waldochoerus bassleri as well as in Tayassu and Dicotyles (instead of a quadrangular molar outline referred to by these authors).

According to Frailey and Campbell (2012), Waldochoerus differs from Dicotyles and can be considered a distinct genus by having: temporal and digastric fossae deeper; coronoid process with central axis close to vertical and mandibular notch wide (versus coronoid process with anterior tilt to vertical axis and mandibular notch narrow in Dicotyles ); higher placement of mandibular condyle; posterior margin of ascending ramus below condyle straight for more than half the height of the ramus before curving smoothly anteriad (posterior margin smoothly curved, beginning at base of condyle in Dicotyles ); mandibular angle without ventral extension below ramus (significant ventral extension in Dicotyles ); extremely shallow postdigastric sulcus (ventral extension of mandibular angle results in deep postdigastric sulcus in Dicotyles ); ascending ramus and angle strongly curved medially, in posterior view (comparatively straight in Dicotyles ); ascending rami diverge sharply laterad from vertical plane of horizontal rami posterior to m3, in superior view (little or no divergence in Dicotyles ); smooth lateral surface of horizontal ramus (horizontal ramus bulges laterad at m 2–3 in Dicotyles ); slight medial rotation of m3 (versus greater rotation involving m 1–3 in Dicotyles ); and teeth with taller bases and rounded, bulbous conids. Nevertheless, all the characters listed by Frailey and Campbell (2012) fall within the variation range of Dicotyles tajacu , as we describe below (figs. 3, 4).

Higher placement of mandibular condyle: This feature is commonly observed in both Tayassu and Dicotyles .

Posterior margin of ascending ramus below condyle straight for more than half height of ramus before curving smoothly anteriad (posterior margin smoothly curved beginning at base of condyle in Dicotyles ): This character is quite different from most specimens of Dicotyles ; however, some Brazilian specimens of this genus have this characteristic.

Ascending ramus and angle strongly curved medially, in posterior view (comparatively straight in Dicotyles ): The ascending ramus and angle are also strongly curved medially in both Tayassu and Dicotyles (fig. 4B).

Ascending rami diverge sharply laterad from vertical plane of horizontal rami posterior to m3, in superior view (little or no divergence in Dicotyles ): This feature observed in Waldochoerus bassleri is similarly developed in both Tayassu and Dicotyles .

Slight medial rotation of m3 (versus greater rotation involving m 1–3 in Dicotyles ): This character is not clear. However, it is noteworthy that the tooth series observed in Waldochoerus bassleri are quite similar to those observed in both extant peccaries.

Teeth with taller bases and rounded, bulbous conids: This feature is the same as observed in Dicotyles . However, taking into account the variability of this feature in both Tayassu and Dicotyles , we consider it a nondiagnostic character and therefore not useful to differentiate taxa.

Features of the diagnosis of Waldochoerus bassleri given by Frailey and Campbell (2012: 866–869) correspond in fact to diagnostic features of the species Dicotyles tajacu , such as: short to medium-sized peccary, short snout, p4 submolariform and lower molars multicuspidate with minor cuspids ( Gasparini, 2007). The teeth observed in the specimens from Peru are typically bunodont instead of the selenodont crown morphology referred to by Frailey and Campbell (2012). These authors also mention as a diagnostic character the presence of lower premolars with trigonids only slightly taller than talonids, but, as already stated, the height of the trigonid is variable in tayassuids with bunodont teeth.

The species Dicotyles tajacu has the largest geographic distribution of any living tayassuid, recorded from north-central Argentina to the southwestern United States ( Gasparini et al., 2006; Gasparini, 2013), and occupies diverse habitats (forests and woodlands, savannas, and deserts) throughout this distribution. Taking into account the morphological and morphometric characters observed in the Peruvian specimens and comparing them with other fossil and living Tayassuidae specimens, we conclude Waldochoerus bassleri is based on specimens of Dicotyles tajacu . Therefore, we consider W. bassleri a junior subjective synonym of D. tajacu .

CETARTIODACTYLA Montgelard, Catzeflis and Douzery, 1997

RUMINANTIA Scopoli, 1777