Traversodontid Cynodont Research Articles

Biostratigraphic significance of a new record of Protuberum cabralense, a bizarre traversodontid cynodont from the Middle‑Late Triassic of Southern Brazil

ABSTRACT Traversodontid cynodonts are one of the most abundant and diverse groups of tetrapods in the Triassic assemblages of Brazil. These cynodonts are distributed across four Brazilian Assemblage Zones (AZ), ranging from the late Ladinian to the early Norian. The most taxonomically diverse record comes from the Dinodontosaurus AZ, which has so far yielded at least six traversodontid genera. Among these taxa, Protuberum cabralense represents one of the most bizarre forms. This cynodont is characterised by the presence of enlarged and rounded protuberances along the dorsal surface of the ribs, the vertebral neural spines and dorsal portion of the iliac blades. These structures have been suggested to serve as a defensive mechanism or related to burrowing/digging habits. We report the first occurrence of P. cabralense at the Linha Várzea 1 site, located in the municipality of Paraíso do Sul, Brazil. This site is considered late Ladinian to early Carnian in age. The new material consists of five rib fragments, which possess the characteristic protuberances on their dorsal surface. A biostratigraphic investigation demonstrates the absence of P. cabralense in fossiliferous sites that yielded the cynodonts Luangwa. This observation contributes to the discussion regarding a potential subdivision within the Dinodontosaurus AZ.

Stranger in the nest: On the biostratigraphic relevance of a new record of a traversodontid cynodont in southern Brazil (Candelária Sequence, Upper Triassic)

The Várzea do Agudo is an Upper Triassic site of the Candelária Sequence of Southern Brazil that boasts an extensive fossil record. It is assigned to the Exaeretodon subzone of the Hyperodapedon AZ (mid-late Carnian) mainly due to the prevalent presence of the traversodontid Exaeretodon riograndensis — up to now the sole traversodontid discovered at the site. In this study, we report the first record of the traversodontid Siriusgnathus niemeyerorum in the Várzea do Agudo site. The new specimen was excavated from the upper layers of the outcrop. Its identification as S. niemeyerorum is substantiated by diagnostic features such as a poorly developed interorbital depression, an inconspicuous suborbital process of the jugal, a not deeply concave base of the lambdoidal crest, the distal accessory labial cusp of the upper postcanines more labially oriented than E. riograndensis, and two upper incisors — so far, a trait autapomorphic to the species among traversodontids. The age of the type locality of S. niemeyerorum has been a subject of debate. Whereas the Siriusgnathus-bearing sites had been associated with younger levels than those of the Hyperodapedon AZ, the absence of index fossils hampered proper biostratigraphic approaches. The finding of a S. niemeyerorum specimen in the same site as E. riograndensis poses a challenging scenario for the biostratigraphy of the fossiliferous outcrops of the municipality of Agudo. It is noteworthy, however, that the new specimen was excavated above the layers yielding E. riograndensis. This raises the question of whether the fossiliferous stratum of the Várzea do Agudo site was deposited in a single event or in a short period, or if it reflects two different time horizons. In the case of the latter, the existence of early Norian sites with distinct faunal composition near the Siriusgnathus-bearing sites could imply the existence of an intermediate fauna between this AZ and the Exaeretodon subzone of the Hyperodapedon AZ, of which S. niemeyerorum would be a constituent. Considering this context, this study discusses the possible biostratigraphic implications of the new record for the biostratigraphy of the sites of the Candelária Sequence.

3D models related to the publication: Old fossil findings in the Upper Triassic rocks of southern Brazil improve diversity of traversodontid cynodonts (Therapsida, Cynodontia)

3D models related to the publication: Old fossil findings in the Upper Triassic rocks of southern Brazil improve diversity of traversodontid cynodonts (Therapsida, Cynodontia)

Old fossil findings in the Upper Triassic rocks of southern Brazil improve diversity of traversodontid cynodonts (Therapsida, Cynodontia).

In this contribution we describe a new genus and species of gomphodontosuchine cynodont from the Late Triassic Hyperodapedon Assemblage Zone (AZ) of the Santa Maria Supersequence of southern Brazil, based on material collected 20 years ago. The new taxon, Santagnathus mariensis gen. et sp. nov., is based on numerous cranial and postcranial remains, which altogether provide data on several parts of the skeleton. Santagnathus mariensis is closely related to Siriusgnathus niemeyerorum and Exaeretodon spp. and expands the knowledge about gomphodontosuchine cynodonts. Morphologically, the new species has a skull bauplan particularly similar to S. niemeyerorum and E. riograndensis, differing from them by a unique combination of traits such as three upper incisors, the absence of a descending process in the jugal, a more posterior position of the postorbital bar and a preorbital region larger than the temporal one. The new traversodontid was found associated with the rhynchosaur Hyperodapedon sp., corroborating the assignment of the cynodont fossils to the Hyperodapedon AZ. We also provide comments on the status of the Argentine traversodontid cynodont Proexaeretodon vincei, typically considered a junior synonym of Exaeretodon argentinus, and here accepted as a valid taxon.

A new ‘rauisuchian’ archosaur from the Middle Triassic Omingonde Formation (Karoo Supergroup) of Namibia

The Middle Triassic uppermost Omingonde Formation of Namibia records a fossil tetrapod fauna including stahleckeriid dicynodonts and probainognathian and traversodontid cynodonts, similar to other contemporary Gondwanan deposits. GSN F382 is a large predatory ‘rauisuchian’ archosaur from the uppermost Omingonde Formation that was originally identified as an erythrosuchid archosauriform. In this study, we provide a detailed anatomical description and phylogenetic analysis of the specimen and diagnose it as a new taxon, Etjosuchus recurvidens. Etjosuchus is a non-crocodylomorph loricatan, branching earlier than Rauisuchidae and Crocodylomorpha. The addition of this large-bodied carnivorous pseudosuchian archosaur to the uppermost Omingonde tetrapod assemblage reinforces its faunal similarity to other Middle to Late Triassic Gondwanan ecosystems such as those in the Santa Maria Formation of Brazil, the Chañares Formation of Argentina and the Manda Beds of Tanzania. http://zoobank.org/urn:lsid:zoobank.org:pub:F5035597-24E0-4DA5-B89D-D3CF8851A8FF

The nasal cavity of two traversodontid cynodonts (Eucynodontia, Gomphodontia) from the Upper Triassic of Brazil

AbstractTraversodontidae is a group of Triassic herbivorous/omnivorous cynodonts that represents the most diversified lineage within Cynognathia. In southern Brazil, a rich fossil record of late Middle/mid-Late Triassic cynodonts has been documented, withExaeretodon riograndensisAbdala, Barberena, and Dornelles, 2002 andSiriusgnathus niemeyerorumPavanatto et al., 2018 representing two abundant and well-documented traversodontids. The present study provides a comparative analysis of the morphology of the nasal cavity, nasal recesses, nasolacrimal duct, and maxillary canals of both species using computed tomography, highlighting the changes that occurred in parallel to the origin of mammaliaforms. Our results show that there were no ossified turbinals or a cribriform plate delimiting the posterior end of the nasal cavity, suggesting these structures were probably cartilaginous as in nonmammaliaform cynodonts. Both species show lateral ridges on the internal surface of the roof of the nasal cavity, but the median ridge for the attachment of a nasal septum is absent.Exaeretodon riograndensisandS. niemeyerorumshow recesses on the dorsal region of the nasal cavity, which increase the volume of the nasal cavity, potentially enhancing the olfactory chamber and contributing to the sense of smell. On the lateral sides of the nasal cavity, the analyzed taxa show a well-developed maxillary recess. AlthoughE. riograndensisandS. niemeyerorumhave roughly similar nasal cavities, in the former taxon, the space between the left and right dorsal recesses of the nasal cavity is uniform along its entire extension, whereas this space narrows posteriorly inS. niemeyerorum. Finally, the nasolacrimal duct ofS. niemeyerorumis more inclined anteroposteriorly than inE. riograndensis.

A new theropod dinosaur from a peculiar Late Triassic assemblage of southern Brazil

The early evolution of theropod dinosaurs is poorly understood. Whereas sauropodomorphs are well-known from the oldest dinosaur bearing outcrops, the record of theropods is fragmentary and ambiguous. The Triassic deposits from Brazil yielded some of the oldest dinosaurs worldwide. These dinosaurs came from two distinct Assemblage Zones (AZ): the Hyperodapedon AZ (Carnian) and the Riograndia AZ (early Norian). Here, a specimen previously assigned to cf. Dinosauromorpha is reassessed. CAPPA/UFSM 0157 comes from an enigmatic assemblage with predominance of the traversodotind cynodont Siriusgnathus. This assemblage has been tentatively assigned to the Riograndia AZ. However, the absence of index fossils still hampers a reliable assignation. The specimen, which comprises a proximal portion of a left femur, belongs to a new theropod taxon erected here as Erythrovenator jacuiensis gen. et sp. nov. The new dinosaur differs from all other known Triassic dinosaurs based on the absence of a raised dorsolateral trochanter of the femur. Erythrovenator jacuiensis gen. et sp. nov. is regarded as a theropod on the basis of the pyramidal shape of the anterior trochanter in anterior view. The results of a phylogenetic analysis corroborate this assignation. Therefore, the new dinosaur represents one of the oldest theropod dinosaurs worldwide, shedding lights on some of the earliest theropod features. Finally, the new specimen also represents the first carnivorous dinosaur from the assemblage dominated by the traversodontid cynodont Siriusgnathus, increasing our knowledge of the faunal content of this enigmatic assemblage.

3D models related to the publication: A new traversodontid cynodont with a peculiar postcanine dentition from the Middle/Late Triassic of Namibia and dental evolution in basal gomphodonts.

3D models related to the publication: A new traversodontid cynodont with a peculiar postcanine dentition from the Middle/Late Triassic of Namibia and dental evolution in basal gomphodonts.

Biostratigraphy of theScalenodontoidesAssemblage Zone (Stormberg Group, Karoo Supergroup), South Africa

AbstractThe Scalenodontoides Assemblage Zone (SAZ) is the oldest fossil tetrapod biozone of the Stormberg Group (Karoo Supergroup) and preserves the oldest dinosaur bearing deposits in the Karoo Basin. The SAZ represents a revision of the ‘Euskelosaurus’ Range Zone, whose taxonomic basis has been undermined because ‘Euskelosaurus’ is well demonstrated to be a nomen dubium. Recent qualitative and quantitative investigations into the biostratigraphy of the Elliot and Clarens formations have resulted in the first biostratigraphic review of all lower Elliot Formation (lEF) taxa in nearly 40 years. Thus, we replace the ‘Euskelosaurus’ Range Zone with a new biostratigraphic assemblage zone, the Scalenodontoides Assemblage Zone (SAZ). Named after the traversodontid cynodont Scalenodontoides macrodontes, which co-occurs with the sauropodomorphs Blikanasaurus cromptoni and Melanorosaurus readi. The SAZ is currently accepted to range in age between the upper Norian and Rhaetian. Our new biozone, which reaches a maximum thickness of ~200 m, is wholly contained within the lower Elliot Formation (Stormberg Group, Karoo Supergroup).

A New Prozostrodontian Cynodont (Eucynodontia, Probainognathia) from the Upper Triassic of Southern Brazil

ABSTRACT Probainognathian cynodonts are well represented in the fossil record from the Middle and Upper Triassic of South America, especially in Brazil and Argentina. In this contribution, we describe a new genus and species of non-mammaliaform prozostrodontian cynodont from southern Brazil. The new taxon comes from the Niemeyer Site, a locality in which the traversodontid cynodont Siriusgnathus niemeyerorum is numerically dominant, whereas probainognathians and other tetrapods are comparatively scarce. The fauna from the Niemeyer Site was putatively assigned to the Riograndia Assemblage Zone (Norian age) recently, although none of the index fossils for that biozone (e.g., Riograndia, Clevosaurus, Jachaleria) have so far been discovered at this locality. The new cynodont taxon is based on a left lower jaw with the canine and six (pc2–pc7) well-preserved postcanines (CAPPA/UFSM 0262, holotype), and a second referred specimen (CAPPA/UFSM 0208, paratype), which includes a right lower jaw with incisors, canine, and seven (pc1–pc7) postcanines, with pc6–pc7 being the best preserved. These specimens have a robust dentary, a long and dorsoventrally tall Meckelian groove, unserrated canines, and unserrated, sectorial postcanine teeth with posteriorly inclined cusps and a poorly developed lingual cingulum. This combination of features is unknown in other Carnian and Norian non-mammaliaform cynodonts. The new taxon contributes to our knowledge of the evolutionary radiation of small prozostrodonts that occurred in western Gondwana during the Late Triassic and led to the emergence of several important cynodont groups, including Mammaliaformes. http://zoobank.org/urn:lsid:zoobank.org:pub:FDC21881-532B-490A-96A1-A65EA5F62737

3D models related to the publication: Virtual reconstruction of cranial endocasts of traversodontid cynodonts (Eucynodontia: Gomphodontia) from the upper Triassic of Southern Brazil.

3D models related to the publication: Virtual reconstruction of cranial endocasts of traversodontid cynodonts (Eucynodontia: Gomphodontia) from the upper Triassic of Southern Brazil.

On the occurrence of the traversodontid Massetognathus ochagaviae (Synapsida, Cynodontia) in the early late Triassic Santacruzodon Assemblage Zone (Santa Maria Supersequence, southern Brazil): Taxonomic and biostratigraphic implications

The traversodontid cynodont Massetognathus ochagaviae is confirmed for the first time in the Santacruzodon Assemblage Zone (Carnian) of the Upper Santa Maria Supersequence of Brazil. Previously to this record, the taxon was known from the Massetognathus-Chanaresuchus AZ of the Chañares Formation, in Argentina (early Carnian) and the Dinodontosaurus AZ of the Santa Maria Supersequence, Brazil (late Ladinian-early Carnian). The studied material was collected in the Schöenstatt outcrop in Santa Cruz do Sul municipality, state of Rio Grande do Sul. The attribution to the species M. ochagaviae is based on the labial border of the upper postcanines teeth extending outward to form an isosceles triangle, one of the diagnosis features of the species, the subrectangular shape and the presence of a short lingual ridge in the lower postcanines, and others traits shared with M. pascuali and M. ochagaviae, as the general morphology of skull, with a lateral platform on the maxilla, 10 to 12 upper postcanine teeth with posterior cingulum, and up to 11 lower postcanine teeth with the transverse mesial width wider than the distal. A cladistic analysis placed the new specimen as sister-group of M. ochagaviae. The Schöenstatt outcrop is the best-studied fossil-bearing site of the Santacruzodon AZ, in which the traversodontid cynodonts are the dominant faunal components, representing 82% of the collected specimens. The Santacruzodon AZ, correlated to the Malagasy basal “Isalo II” beds of the Morondava Basin, also shares taxa with the Dinodontosaurus AZ and the Chañares and the Ischigualasto formations, representing a unique Triassic association. As a consequence, the Santacruzodon AZ represents a faunal association still not recognized in the Ischigualasto-Villa Unión Basin. New data from the Santacruzodon AZ is required to further address these questions.

A new Upper Triassic cynodont-bearing fossiliferous site from southern Brazil, with taphonomic remarks and description of a new traversodontid taxon

A new Upper Triassic fossiliferous outcrop, the Niemeyer Site, from the Santa Maria Supersequence (Paraná Basin, Southern Brazil) is reported. The lithology found in this locality is consistent with that found in the Candelária Sequence. The high prevalence of traversodontid cynodonts in this site is particularly notable, with collected specimens mostly composed of isolated bones and fragmentary specimens, but also including well-preserved skulls and mandibles. Probainognathian cynodonts and archosauromorphs are also present, but they are rare in comparison. There is a predominance of Voorhies Group III (Group III > Group I > Group II) for the specimens so far collected. These data, as well as the sedimentary data of the outcrop, indicate a mostly autochthonous fossiliferous assemblage. Some specimens display evidence of ichnological activity of invertebrate scavengers (bone alteration comprising small tubules, channels and isolated boreholes). A remarkable aspect of this site is the presence of a new traversodontid cynodont closely related to Exaeretodon. Although similar to the former taxon, the new taxonomic unit shows a unique combination of several craniodental features not present in other cynodonts. Given that no traversodontids are recorded in the uppermost levels of the Candelária Sequence, this site is likely placed in the lower levels of this unit, with the fauna suggesting a Carnian age.

Re-examination of the Jurassic Mammaliaform Docodon victor by Computed Tomography and Occlusal Functional Analysis

Docodon was the first described docodont, and has long featured prominently in the comparative and functional morphology of mammaliaform mandibles and teeth. We have now re-examined the dental and mandibular fossils of Docodon from Yale Quarry 9 at the Como Bluff site in the Late Jurassic Morrison Formation, using Computed Tomography (CT) scans and 3D image analyses. Our CT study revealed that some features used to distinguish the several Docodon “species” in historical studies many decades ago were based on incorrect manual restoration of mandibles, and on variable features of deciduous premolars, which are replaced in typical mammaliaform fashion. This supports a long-held notion that the multiple species of Docodon from the same quarry of the Morrison Formation are over-split and should be synonymized. We formally propose that the specimens examined in this study be synonymized under Docodon victor. Our new Occlusal Fingerprint Analysis (OFA) of Docodon molars supports the hypothesis that Docodon had a consistent dorso-posterior or palinal component in chewing in the disto-distolingual to distolingual direction. This helps to resolve the controversial historical alternative hypotheses postulated for tooth occlusion in the taxon. The Docodon occlusal pattern is likely a derived feature, evolved within Docodonta. A posterior component in the occlusal trajectory is a functional convergence of Docodon on unrelated traversodontid cynodonts.

The postcranial skeleton of Boreogomphodon (Cynodontia: Traversodontidae) from the Upper Triassic of North Carolina, USA and the comparison with other traversodontids.

Postcranial remains of Boreogomphodon from the Upper Triassic of North Carolina are described and compared to those of other known traversodontid cynodonts. The postcranial skeleton of Boreogomphodon is characterized by four sacral ribs, simple ribs lacking costal plates, the extension of the scapular neck below the acromion process, a short scapular facet on the procoracoid, a concave anterior margin of the procoracoid, humerus entepicondyle with smooth corner, and the presence of a fifth distal carpal. Four types of ribs are identified among traversodontids: ‘normal’ form, tubercular rib, costal plate, and Y-shaped rib. Fossorial behavior is suggested for traversodontids with elaborate costal plates. Within Traversodontidae, the procoracoid is relatively small; the anterior process of the iliac blade extends anteroventrally to different degrees in different taxa, which facilitates retraction of the femur; and the limb bones show allometric growth in terms of length and width.

A new gomphodont cynodont (Traversodontidae) from the Middle–Late Triassic Dinodontosaurus Assemblage Zone of the Santa Maria Supersequence, Brazil

AbstractThe tetrapod faunas from the terrestrial Middle–Late Triassic basins of Africa and South America are among the richest in the world, especially in non‐mammalian cynodonts. Despite the great abundance of cynodont specimens found in these basins, there are few known taxa that exhibit interbasinal distributions. Here we describe a new species of traversodontid cynodont of the genus Scalenodon from the Triassic Dinodontosaurus Assemblage Zone of the Santa Maria Supersequence, from the state of Rio Grande do Sul, Brazil. Scalenodon ribeiroae sp. nov. is based on a partial skull that possesses a combination of features not observed in any other South American traversodontid: ellipsoid upper postcanines with the transverse crest formed by three cusps, lacking a mesiobuccal accessory cusp, and with lingual cusp projected lingually creating a concave lingual surface on the upper postcanines; the paracanine fossa is positioned medially to the upper canine, and jugal lacks a suborbital process. A phylogenetic analysis places the new taxon in a basal position within the Family Traversodontidae, with the African Scalenodon angustifrons as sister‐taxon. The new specimen of Scalenodon represents the first record of this genus outside of the Manda Beds of Tanzania, and reinforces the biostratigraphical and biogeographical connection between Gondwanan Middle–Late Triassic tetrapod faunas. Although recent advances have been made, our current knowledge of these faunas is limited by the lack of absolute dates for most units and by uncertainties in the taxonomy and stratigraphical provenance of key fossils.

Vertebrate fauna from the Late Triassic Tiki Formation of India: new finds and their biostratigraphic implications

Recent work on the Tiki Formation has resulted in the collection of new and varied vertebrate micro–and megafossils, including a new bonebed containing low diversity, mono–dominant, multitaxic vertebrate accumulation where the rhynchosaur, Hyperodapedon tikiensis constitute the dominant component. This bonebed has also yielded a large traversodontid cynodont Ruberodon roychowdhurii. In addition, there are several diagnostic postcrania such as vertebrae and incomplete limb bones belonging to a basal saurischian dinosaur. Systematic exploration and collection has yielded numerous isolated teeth and postcrania of small vertebrates such as different types of freshwater sharks, bony fishes, archosauriforms, lepidosauromorphs, cynodonts and other reptiles. Based on its fossil flora and fauna, the Tiki Formation is globally correlated with other coeval horizons such as the lower member of the Maleri Formation of the Pranhita–Godavari basin, the upper part of the Santa Maria Formation of Brazil, the Camp Springs and lower Tecovas formations of the Chinle Group, USA. A Carnian (Otischalkian to early Adamanian) age is proposed for the Tiki Formation.

The Malagasy cynodont Menadon besairiei (Cynodontia; Traversodontidae) in the Middle–Upper Triassic of Brazil

ABSTRACTThe traversodontid cynodont Menadon besairiei, previously known from the ‘Isalo II’ group of Madagascar, is reported for the first time from the Triassic of southern Brazil. New material referable to M. besairiei was collected in the Schoenstatt outcrop (Santa Cruz do Sul municipality), which belongs to the Santacruzodon Assemblage Zone (Carnian) in the Santa Maria Supersequence. Their attribution to the Malagasy taxon is based on the presence of a deep snout; four upper incisors, with procumbent first and second incisors, and three lower, procumbent incisors; five upper postcanines, the first one ‘peg-like’; six lower postcanines, the two most anterior and the most posterior being reduced; the quadrangular form of the postcanines; a pterygoid reaching the jugal and excluding the maxilla from the suborbital fenestra; a mandible with a tall coronoid process covering the last lower postcanine laterally; and a posteriorly projected angular process. A cladistic analysis of traversodontid cynodonts was performed based on a matrix composed of 30 taxa and 78 characters. In the resulting trees, M. besairiei nested within the clade Gomphodontosuchinae, the only traversodontid subclade reasonably well supported. Thus, the presence of M. besairiei is established in the Santa Cruz do Sul fauna, constituting the first record for South America and confirming the previously proposed biostratigraphic correlation between the ‘Isalo II’ and the Santacruzodon Assemblage Zone.Citation for this article: Melo, T. P., F. Abdala, and M. B. Soares. 2015. The Malagasy Cynodont Menadon Besairiei (Cynodontia; Traversodontidae) in the Middle–Upper Triassic of Brazil. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2014.1002562.

Biogenic control on the origin of a vertebrate monotypic accumulation from the Late Triassic of southern Brazil

This study is a taphonomic investigation of a new Late Triassic monotypic association from the Hyperodapedon Assemblage Zone (Santa Maria Formation, southern Brazil). All skeletal elements belong to the traversodontid cynodont Exaeretodon, representing a minimum of four individuals from different ontogenetic stages. Biogenic traces are identifiable on some elements, such as invertebrate scavenging traces, vertebrate bite marks, and evidence of trampling which was probably responsible for accelerating the disarticulation of upper postcanine teeth and for fracturing a skull and a lower jaw. We classify this accumulation as generated by extrinsic biogenic action (predation/necrophagy and possibly trampling) due to the following reasons: (i) random spatial orientation of the elements enclosed into the matrix; (ii) absence of hydraulic equivalence among the specimens and presence of mudstone lenses in close association with the fossils; (iii) presence of nearly all Voorhies’ groups; (iv) association of a large number of cranial elements presenting different stages of disarticulation; and (v) presence of biogenic traces. Both disarticulation patterns and invertebrate scavenging traces indicate that the bones remained exposed for some time before burial. During this time of exposure, carnivore vertebrates also scavenged on some nutritive and transportable postcranial elements. We suggest an ecteniniid cynodont as a potential modifier agent (predation/necrophagy) of this particular monotypic accumulation of synapsids.

A new Late Triassic traversodontid cynodont (Therapsida, Eucynodontia) from India

ABSTRACT—A large traversodontid cynodont Ruberodon roychowdhurii, gen et. sp. nov., is described from the Late Triassic Tiki Formation of the Rewa Gondwana Basin, India, based on an ontogenetic series of five partial lower jaws. Ruberodon is characterized by a robust and deep dentary symphysis, lower dental formula of i3-c1-pc9, procumbent and hypertrophied first lower incisor, a large canine, long diastema between the lower canine and first postcanine, and a high coronoid process at 60° to the horizontal tooth row. With growth, the symphyseal region became relatively more slender with lengthening of the diastema. Phylogenetic analysis based on 19 taxa and 35 craniodental characters places Ruberodon within the clade containing Gomphodontosuchus, Menadon, Protuberum, Scalenodontoides, and the multispecific Exaeretodon. The new genus forms a sister taxon to E. statisticae and is more advanced than E. riograndensis and E. argentinus based on the presence of a strong coronoid ridge anterior to the masseteric fossa. Based on its tetrapod assemblage, the Tiki Formation may be globally correlated with other formations such as the lower part of the Maleri Formation of India, the Isalo II Beds of Madagascar, and the upper part of the Santa Maria Formation of Brazil. An early Carnian age is proposed for the Tiki Formation. http://zoobank.org/urn:lsid:zoobank.org:pub:80D363C5-D311-4788-90E2-3BE4CFC35FEESUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP