Sivaonyx sarwari, Mahmood & Morlo & Abbas & Babar & Khan, 2025

Sivaonyx sarwari n. sp.

(Fig. 2B1-B3)

urn:lsid:zoobank.org:act:123FFCDF-CE50-4AE6-AB31-1F563001A874

DERIVATION OF NAME. — After Dr Muhammad Sarwar, the second vertebrate palaeontologist of the Punjab University and who have done extensive field work during the 1963-1977 throughout Pakistan, that resulted in the identification and exploration of new localities and became a source of guidance for the field work for the future palaeontologists of Pakistan.

HOLOTYPE. — PUPC 17/64 , lP4.

TYPE LOCALITY. — Hasnot, Jhelum, Punjab, Pakistan.

DIAGNOSIS. — A small Sivaonyx species having P4 with round borders/external walls, basal lingual cingulum is straight at mesial border, postparacrista short and having less buccal concavity, lack a cusplet between proto- and hypocone, small mesial valley hence, less pinched mesial border, and very long posthypocrista, the crest that joins hypocone with metastyle/metacone.

DIFFERENTIAL DIAGNOSIS. — Differs from all Sivaonyx species being small in size, having round outline, basal lingual cingulum is straight at mesial border, and small mesial valley hence, less pinched mesial border. It differs from Sivaonyx bathygnathus in having short postparacrista, less spaced proto- and hypocone, and having no cusplet between proto- and hypocone; from Sivaonyx gandakasensis in short postparacrista, long posthypocrista, and more buccal concavity of postparacrista; from Sivaonyx hessicus Lydekker, 1890 in having weak buccal concavity of postparacrista, no cusplet between proto- and hypocone, very long posthypocrista; from Sivaonyx hendeyi Morales, Pickford & Soria, 2005 in lacking notch between paracone and metastyle, having very long posthypocrista, and weak buccal cingulum; from Sivaonyx ekecaman Werdelin, 2003 in having longer pre- and postparacrista, slightly distally positioned protocone, lack of notch between paracone and metastyle, weak buccal concavity of postparacrista, no cusplet between proto- and hypocone, large median valley, and very long posthypocrista; and from Sivaonyx soriae in having slightly distal position of protocone, weak buccal concavity of postparacrista, no cusplet between proto- and hypocone, very long posthypocrista. STRATIGRAPHIC RANGE. — Dhok Pathan Formation of the Middle Siwaliks (Late Miocene).

DESCRIPTION

PUPC 17/64 is nearly rectangular with round outline, well-preserved and slightly worn (Fig. 2B1-B3). All the cusps are well-developed and prominent. The paracone is the highest, massive, with a rounded external wall and a prominent parastyle. The parastyle is low in height and it is separated from paracone by a small notch. Three crests originate from the paracone, mesial crest (preparacrista) connects the paracone to the parastyle, distal (postparacrista) to the metacone and the metacrista, and the third (lingual crest) connects to the protocone through crista obliqua. The metacrista is small and the metastyle/metacone is bulbous. The paracone is connected to the metacone. A prominent slanting cingulum is also present between the paracone and metacone and is connected to metastyle. The coupled protocone and hypocone are well-developed and distinct, separated by only a small notch. The protocone is slightly higher than the hypocone. The hypocrista is extremely long and becomes slightly round distally, rendering tooth round outline. The median fossette is large, oval in shape and separates trigon and talon. A thick cingulum fully covers the base of the tooth that has three roots (Fig. 2B1-B3).

COMPARISON

The presence of a protocone far from the paracone and a large cingulum that covers the base of the tooth in PUPC 17/64 differentiate it from Paludolutra , and presence of a less developed hypocone, a protocone far from the paracone, a more sectorial paracone-metastyle, and that it is longer than wide in addition to its small size differentiate it from Enhydriodon . Vishnuonyx and Sivaonyx are the other two “enhydriodontine” genera present in the Siwaliks. PUPC 17/64 differs from the P4 of all Vishnuonyx species in having round outline, robust parastyle, short metacrista, very long posthypocrista, and wider central basin in addition to incomplete lingual shelf. Even the space between the protocone and hypocone is smaller in PUPC 17/64 than in Vishnuonyx while the space between the parastyle and paracone is wider in Vishnuonyx . Sivaonyx is represented by two species, a small, Sivaonyx gandakasensis and a large, S. bathygnathus ( Pickford 2007; Grohé et al. 2013; Ghaffar & Akhtar 2016). PUPC 17/64 is smaller than any known P4 of both of these species ( Table 2 View TABLE ). However, it shares more morphological similarity with the P4, GSI-D 157, of Sivaonyx bathygnathus first described and figured by Pilgrim (1932: pl. 2, fig. 16) and later figured by Pickford (2007: fig. 9A). These similarities include the large paracone with a round lingual wall, low but heavy parastyle, a large and bulbous metastyle/metacone, a large and wide median fossette, and a very long posthypocrista (Fig. 2B1-B3). Based on these similarities, we are allocating PUPC 17/64 to Sivaonyx . However, due to its minute size, its rounded outline, the short metacrista, small space between protocone and hypocone, the more developed cingulum, less pinched preprotocrista or anterotransverse wall of the tooth, we do not assign it to one of the known species but designate it as a new species, Sivaonyx sarwari n. sp. It differs from other Sivaonyx species as given in differential diagnosis.