New cynodonts (Therapsida, Eucynodontia) from the Late Triassic of India and their significances

Abstract

The Upper Triassic Tiki Formation of India has yielded several new cynodont taxa, which are described on the basis of multiple isolated teeth and a jaw fragment. A new species of dromatheriid, Rewaconodon indicus, is defined by a tri- and tetracuspid asymmetric crown, long anterior edge of the major cusp a, cingular cusps d and f, and marked constriction at the crown-root junction. Another new dromatheriid, Inditherium floris n. gen. n. sp., is characterized by a broad, flower-shaped pentacuspid crown, multiple cingular cusps, and a weak lingual cingulum is also described from the same horizon. In addition, a new mammaliamorph taxon, Tikiodon cromptoni n. gen. n. sp., is established on a tooth specimen, which has a shovel-shaped crown, three closely spaced main cusps, a pronounced lingual cingulum with multiple cingular cusps, and a root of incomplete root bifurcation. Such a tooth morphology occupies an intermediate position between the non-mammalian cynodonts and the early mammals, as is evident from the co-occurrence of various cynodont dental morphotypes in the Tiki Formation. Moreover, Late Triassic cynodonts occurred along narrow belts demarcated by paleolatitudes, though the Indian fauna shows both Laurasian and Gondwanan affinities. UUID: http://zoobank.org/c2c575ad-ee23-4f33-8a30-661c548a5b17

Bone‐bearing coprolites from the Upper Triassic of India: ichnotaxonomy, probable producers and predator–prey relationships

“…In addition, Bhat et al . (2021) reported several non‐mammalian cynodonts from the same bonebed, which were the probable producers of these coprolites. The coprolites of NSC‐V possess a prominent triangular–subtriangular cross‐section with prominent edges. As in other non‐spiral coprolites, these contain numerous fish scales, teeth and other skeletal fragments as inclusions, suggesting carnivory for the producers.…”

“…1C) as an important component of a metoposaurid‐dominated, multitaxic and mixed bonebed (Rakshit & Ray 2020), which has yielded a highly diverse vertebrate assemblage (Bhat et al . 2018 a , b , 2021; Rakshit et al . 2018; Bhat & Ray 2020; Datta et al .…”

A “Mammalian-like” Pycnodont Fish: Independent Acquisition of Thecodont Implantation, True Vertical Replacement, and Carnassial Dentitions in Carnivorous Mammals and a Peculiar Group of Pycnodont Fish

“…1, 2: generation of a tooth. The oldest age of each taxon is followed by these data [Chondrichthyes, the earliest Devonian: [36]; Actinopterygii, the early Devonian: [37]; Amphibia, early Middle Devonian: [38]; Reptilia, the early Pennsylvanian, the late Carboniferous: [39]; Archosaur, the latest Permian: [40]; Synapsida, the early Pennsylvanian, the late Carboniferous: [41]; Mammalia, the late Carnian to the early/middle Norian, the late Triassic: [42]]. The images have the following credits: Eutheria by Synapsida by Dmitry Bogdanov (Dimetrodon: [43] under CC BY-SA 3.0 license), Archosauromorpha by Maija Karala (Tyrannosaurus rex: [44] under CC BY-SA 3.0 license), Repenomamus by Mateus Zica (Repenomanus: [45] under CC BY-SA 3.0 license), Mesonychia by Zimices (Mesonyx: [46] under CC BY-SA 3.0 license), Sparassodonta by Zimices (Cladosictis: [47] under CC BY-SA 3.0 license).…”

A New Cynodont from the Late Triassic Los Colorados Formation (Argentina, South America) Reveals a Novel Paleobiogeographic Context for Mammalian Ancestors

“…It is in China where the origin of Mammaliaformes is expected (52.03%). However, it must be noted that we did not include Gondwanodon and Tikitherium, from the Late Carnian-Early Norian Tiki Formation (Madhya Pradesh, India), in our analysis as they are both represented by an isolated tooth which is even incompletely preserved in the case of Gondwanodon [45][46][47]. Although never tested phylogenetically, Gondwanodon has been considered to be closely related to Morganucodon [48,49].…”

“…Most scholars agree on the putative probainognathian nature of dromatheriids, a group of small cynodonts represented by isolated teeth or fragments of mandible, mostly discovered in the Laurasia subcontinent and India [47], yet its placement was not cladistically tested. Unfortunately, removal of Microconodon (one of the wildcard taxa in the complete analysis) from our second analysis, does not allow us to inspect the relationship of this lineage.…”