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 : 4-9

TAYASSUIDAE Palmer, 1897

REFERRED MATERIAL: AMNH 55811 (holotype of Sylvochoerus woodburnei Frailey and Campbell, 2012 ), complete left mandible, lacking i1-3 ; LACM 150305 , right mandibular fragment with p4 ; UCMP 118779 , left mandibular fragment with p4–m1 ; USNM 205346 , palate with complete dentition and portion of left zygomatic arch ; USNM 205389 , right M3 ; USNM 513211 , left palatal fragment with M1–3 ; USNM 513212 , left palatal fragment with P2–4 ; USNM 513213 , right radio-ulna ; USNM 513214 , left palatal fragment with M2 ; USNM 513216 , right mandibular fragment with m1–2 ; USNM 513217 , left mandibular fragment with m3 ; USNM 513218 , isolated right m3 ; USNM 513219 , right P3 ; USNM 513220 , left P2 with palatal fragment ; USNM 513221 , partial left ramus with dp3–m2 ; USNM 513224 , right partial M2 .

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

According to Frailey and Campbell (2012), Sylvochoerus has the following diagnostic characters: mandible short and sturdy; postcanine diastema relatively short, deep, and with steep rise to p2; ascending ramus with posterior margin curved in lateral view; high placement of mandibular condyle; forward placement of mandibular condyle; and less procumbent mandibular symphysis.

All 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 noteworthy that the length of the postcanine diastema measured in this genus allows us to consider it as a short diastema (shorter than 50% and longer than 30% of the length of the toothrow; see Gasparini, 2007). Besides that, a short postcanine diastema represents one of the characters that allow grouping it into Tayassuini . This clade is composed of the three living species, Dicotyles tajacu (collared peccary), Tayassu pecari (white-lipped peccary), and Parachoerus wagneri (Chacoan peccary), in addition to the extinct taxa Brasiliochoerus stenocephalus , Parachoerus carlesi , Catagonus metropolitanus , and Catagonus bonaerensis ( Parisi Dutra et al., 2017) .

According to Frailey and Campbell (2012), the new genus Sylvochoerus is a medium- to large-sized peccary with a short snout and a broad cranium. These authors also considered this new taxon to resemble Tayassu but to differ from Dicotyles in the following characters: mandibular ramus with postdigastric sulcus shallower and extending anteriorly only to under m2 (as opposed to under m 1 in Dicotyles ); mandibular rami with inferior margin of diastema rounded mediolaterally (broadening laterally under diastema in Dicotyles ); mandibular condyle higher on ascending ramus; mandibular symphysis recurved anterior to canines (recurved ventral to canines in Dicotyles ); more complex dental pattern with an abundance of minor cuspids; weak lophodonty with wear (weak selenodonty in Dicotyles ); more advanced state of molarization of p4; heel of m3 complex (less integrated and more simple in Dicotyles ).

All these features correspond to those that characterize the genus Tayassu , except the tooth crown morphology, which other authors (Gasparini et al., 2011, 2014) have referred to as bunodont for all the species of Tayassu , Dicotyles , Catagonus , Brasiliochoerus and Parachoerus (teeth of Parachoerus wagneri are referred to as “zygodont,” which is bunodont with relatively high cuspids) ( Gasparini et al., 2009, 2011, 2013, 2019; Prothero and Grenader, 2012; Avilla et al., 2013; Parisi Dutra et al., 2017).

According to Frailey and Campbell (2012), Sylvochoerus differs from Tayassu and can be considered as a different genus, by having: mandibular ramus with nearly consistent depth below the toothrow (i.e., ramus does not lose depth anteriorly; a ramus with reduced depth anteriorly is present in Tayassu ); ascending ramus with anterior edge overlapping part of m3, in lateral view (m3 more exposed in lateral view in Tayassu ); angle of mandible gently curving anteriorly into shallow postdigastric sulcus and extending only slightly below lower margin of horizontal ramus (angle of mandible with abrupt change in curvature leading anteriad into deep postdigastric sulcus and extending well below lower margin of horizontal ramus in Tayassu ); alveoli for incisors more procumbent, directed more anteriad and less dorsad; digastric fossa well differentiated from pterygoid fossa by low, rounded ridge (ridge very low or absent in Tayassu ); digastric fossa more deeply concave, which is accentuated by medial edge of inferior margin of ramus extending mediad to form a shelf; teeth with lower part of crown taller, more broad based, bulbous, and with major cusps shorter and inclined toward long axis of tooth; alveolar margin of canines lying well below line drawn from alveolar margin of the p2–m1 (lies at or only slightly below line in Tayassu ); molars with ribbed furrowing on flanks of cusps, resulting in a sculpted appearance (absent in Tayassu ); dentition with multiple accessory crests and cuspids, producing a more complex occlusal surface than in Tayassu . However, all the characters listed by Frailey and Campbell (2012) fall within the variation range of the monotypic genus Tayassu (i.e., Tayassu pecari ), as we describe below (figs. 1, 2, 4).

Mandibular ramus with nearly consistent depth below toothrow: In their description, Frailey and Campbell (2012) point out that Sylvochoerus has an almost constant depth below the toothrow and claim that in Tayassu pecari , the ramus loses depth anteriorly. In fact, some specimens of Tayassu pecari display slight differences in depth from the anterior to the posterior part of the dentary bone below the toothrow (fig. 1B: arrow); however, these differences are minor (almost imperceptible) in some specimens.

Ascending ramus with anterior edge overlapping part of m 3 in lateral view: This character probably is the most variable feature in the dentary bone (fig. 1B: arrow). In some specimens of Tayassu pecari from Argentina, the anterior part of the ascending ramus overlaps part of m3 as occurs in Sylvochoerus , but in several specimens from central and northern Brazil, the ascending ramus does not overlap the m3. Besides that, this character also varies depending on the ontogenetic age of the specimen (see Margarido et al., 2007).

Angle of mandible gently curving anteriad into shallow postdigastric sulcus and extending only slightly below lower margin of horizontal ramus: Frailey and Campbell (2012) suggest that the postdigastric sulcus in Sylvochoerus is a gently anteriorly curved structure, whereas in Tayassu pecari it is a deep sulcus that abruptly changes the direction of the horizontal ramus of the dentary bone. The holotype of Sy. woodburnei, AMNH 55811, and the two paratypes, USNM 513217 and USNM 513221, as stated by Frailey and Campbell (2012), are damaged due to the fossilization process. These features may be a result of this process; however, some living and fossil individuals of T. pecari show the same shape of the postdigastric sulcus as Sy. woodburnei . This sulcus represents the insertion of the digastric muscle. When contracted, this muscle elevates the hyoid bone and depresses the mandible, a movement involved with opening the mouth. Thus, the shape of the postdigastric sulcus might be related to dietary habits.

Alveoli for incisors more procumbent, directed more anteriad and less dorsad: This character is highly variable in North and South American tayassuid species, so it is not a diagnostic feature useful to differentiate species.

Digastric fossa well differentiated from pterygoid fossa by low, rounded ridge: In Tayassu pecari , this ridge is quite variable (low, very low, or absent), and thus is a nondiagnostic character. This feature, as developed in Sy. woodburnei , is also commonly observed in T. pecari .

Digastric fossa more deeply concave, accentuated by medial edge of inferior margin of ramus extending mediad to form a shelf: The digastric fossa is also deeply concave in Tayassu pecari . The development of a medial edge of the inferior margin of the ramus is variable in specimens of T. pecari .

Teeth with lower part of crown taller, more broad based, bulbous, and with major cusps shorter and inclined toward long axis of tooth: These characters are also observed in Tayassu pecari (fig. 2D).

Alveolar margin of canines lying well below line drawn from alveolar margin of p2–m1 (lies at or only slightly below line in Tayassu ): This feature is developed in tayassuids in general.

Dentition with multiple accessory crests and cuspids, giving a more complex occlusal surface than in Tayassu: Teeth of Sy. woodburnei have the same crown morphology, dental pattern (e.g., placement of major cusps and accessory cuspids and multiplicity of minor crown features), and tooth size observed in Tayassu pecari (fig. 2).

Features listed in the diagnosis of Sylvochoerus woodburnei given by Frailey and Campbell (2012: 854–857) correspond in fact to diagnostic features of Tayassu pecari , such as: medium to large-sized peccary, with a short snout and a broad cranium, p4 molariform, molars multicuspidate with minor cuspids between major cusps ( Gasparini, 2007; Gasparini et al., 2011, 2014). Instead of “indications of lophation resulting from wear in teeth,” we note that the bunodont crown morphology developed in the specimens of Sy. woodburnei shows a transversely oval surface due to wear. Frailey and Campbell also mention as a diagnostic character of Sy. woodburnei the presence of lower premolars with a trigonid much taller than the talonid. It is true that the trigonid is taller than the talonid; however, the height of the trigonid represents a nondiagnostic morphometric feature because it varies in tayassuids with bunodont tooth morphology.

The monotypic genus Tayassu is widely distributed across the Neotropical region from northern Argentina to southern Mexico (Gasparini, 2013; Gasparini et al., 2014), occupying several types of habitats along this distribution. This species has a great ecological tolerance, but it is generally associated with bodies of water. Some authors ( Beck, 2006; Reyna-Hurtado et al., 2009; Sicuro et al., 2011; Hendges et al., 2016, 2019) have pointed out that this animal has a large range of morphological variability due to food habit, sexual dimorphism and ontogenetic age factors.

Taking into account the morphological and morphometric characters observed in specimens described in Frailey and Campbell (2012) and comparing them with other fossil and living Tayassuidae specimens, we conclude Sy. woodburnei is based on specimens of Tayassu pecari . Therefore, we consider Sy. woodburnei a junior subjective synonym of T. pecari .

CETARTIODACTYLA Montgelard, Catzeflis and Douzery, 1997