A new Middle Triassic (Ladinian) trilophosaurid stem-archosaur from Germany increases diversity and temporal range of this clade

Sues, Hans‐Dieter; Schoch, Rainer R.

doi:10.1098/rsos.230083

Cited by 8 publications

(21 citation statements)

References 44 publications

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“…2A, 3A, 6A, B). Similar rows of nutrient foramina can be seen on a horizontal ridge of bone on the dentary of Variodens inopinatus (NHMUK PV R36850; Chambi-Trowell et al, 2021), ventral to the anterior portion of the tooth row of Coelodontognathus ricovi (PIN 4137/127; Sues & Schoch, 2023), in Trilophosaurus buettneri (TMM 31025-5;TMM 31025-125;Spielmann et al, 2008), and in Azendohsaurus madagaskarensis (Nesbitt et al, 2015:fig. 7F).…”

Section: Redescription Of Ucmp 37804mentioning

confidence: 74%

“…7F). Unfortunately, we cannot determine how far anteriorly the series of foramina continues in UCMP 37804, and there is no visible horizontal ridge on the lateral surface of the dentary, unlike those reported on the dentary of Coelodontognathus ricovi (PIN 4137/127; Sues & Schoch, 2023), Variodens inopinatus (NHMUK PV R36850), and Tricuspisaurus thomasi (NHMUK PV R6106) (Chambi-Trowell et al, 2021;Skinner et al, 2020). It is impossible to determine whether such a ridge was present in life in UCMP 37804 because of poor preservation (Figs.…”

Section: Redescription Of Ucmp 37804mentioning

confidence: 89%

“…The NEXUS file of the full data matrix is available on Morpho-Bank (http://morphobank.org/permalink/?P4610), together with the NEXUS files required for performing maximum parsimony and Bayesian inference analyses, .tre files containing the MPTs from each TNT analysis, and the 50% majority rule consensus tree from each MrBayes analysis (accessible as .zip folders in "Documents" section of the same MorphoBank project). Sues and Schoch (2023) recently described Rutiotomodon tytthos, a new trilophosaurid from the Middle Triassic of Germany, and recognized Coelodontognathus ricovi from the Lower Triassic deposits of Russia as the oldest known trilophosaurid. Information from Sues and Schoch (2023) was incorporated in the description and discussion; however, incorporation of Rutiotomodon tytthos and Coelodontognathus ricovi into our modified phylogenetic dataset will be the subject of future work.…”

Section: Phylogenetic Methodsmentioning

confidence: 99%

“…Sues and Schoch (2023) recently described Rutiotomodon tytthos, a new trilophosaurid from the Middle Triassic of Germany, and recognized Coelodontognathus ricovi from the Lower Triassic deposits of Russia as the oldest known trilophosaurid. Information from Sues and Schoch (2023) was incorporated in the description and discussion; however, incorporation of Rutiotomodon tytthos and Coelodontognathus ricovi into our modified phylogenetic dataset will be the subject of future work. Anatomical Abbreviations-c.b., cancellous bone; ci, cingulum; cu, cusp; d, dentary; de, dentine; en, enamel; for, foramina; p.c., pulp cavity; sw, swollen base.…”

Section: Phylogenetic Methodsmentioning

confidence: 99%

“…in UCMP 37804, teeth 9-15 in Variodens (based on the reconstruction of Robinson 1957-equivalent to teeth 5-11 in NHMUK PV R36850, which is missing the anterior dentary teeth), teeth 6-11 of Tricuspisaurus (NHMUK PV R6106-equivalent to teeth 1-6 in fig. 2F of Chambi-Trowell et al, 2021), the available crowns in the maxilla of Rutiotomodon tytthos (SMNS 97028), all except the last erupting crown of Coelodontognathus ricovi (PIN 4137/127, and referred tooth PIN 4137/128) (Sues & Schoch, 2023), and the mediolaterally widened crowns in specimens of Trilophosaurus are considered premolariform ( 3-5) (see below for missing tooth positions and the Discussion for a justification of correlates). Note that the distal crowns of Teraterpeton hrynewichorum (Sues, 2003) bear some similarities with the molariforms of Anisodontosaurus and Variodens (i.e., enlarged swollen base, prominent central cusp), but in the absence of more precise data we refrain from establishing direct homologies among the crowns of these taxa.…”

Section: Note On Anatomical Nomenclaturementioning

confidence: 99%

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New specimen and redescription of Anisodontosaurus greeri (Moenkopi Formation: Middle Triassic) and the spatiotemporal origins of Trilophosauridae

Foffa

Nesbitt

Kligman

et al. 2022

Journal of Vertebrate Paleontology

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Anisodontosaurus greeri is an enigmatic small-bodied tetrapod with a heterodont dentition from the Holbrook Member of the Moenkopi Formation (Middle Triassic) of Arizona (U.S.A.). The evolutionary relationships of this taxon have long been debated and remain uncertain. Using micro-computed tomography (µCT) scans we redescribe the holotype of Anisodontosaurus greeri (UCMP 37804), as well as an additional specimen (MNA.V.1478) that had been informally referred to this taxon. Our new data reveal hidden details of the dentition (i.e., ankylothecodonty and absence of replacement teeth) that, in combination with the tricuspid and mediolaterally expanded crowns, support a referral of both specimens to the archosauromorph clade Trilophosauridae. The referral of MNA.V.1478 to Anisodontosaurus greeri is supported by the unique anatomy of the highly differentiated dentition (i.e., 'figure of 8'-shaped premolariforms in occlusal views; mesiodistally short tooth row; presence of a distal 'molariform' crown). Comparison of Anisodontosaurus greeri with other trilophosaurids highlights marked similarities with Variodens inopinatus from the Upper Triassic deposits of the U.K. Our cladistic analyses confirm these observations, and recover, for the first time, two distinct lineages within Trilophosauridae: one geologically long-lived and comprising Anisodontosaurus and Variodens; and one comprising Tricuspisaurus, Trilophosaurus spp., and Spinosuchus. These results imply that: (i) Anisodontosaurus is one of the oldest known trilophosaurids worldwide and the oldest in North America; (ii) trilophosaurids achieved a broad distribution at low latitudes within western Pangea by the Middle Triassic; (iii) small body sizes were more common than previously thought among trilophosaurids.

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Section: Redescription Of Ucmp 37804mentioning

confidence: 74%

Section: Redescription Of Ucmp 37804mentioning

confidence: 89%

Section: Phylogenetic Methodsmentioning

confidence: 99%

Section: Phylogenetic Methodsmentioning

confidence: 99%

Section: Note On Anatomical Nomenclaturementioning

confidence: 99%

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New specimen and redescription of Anisodontosaurus greeri (Moenkopi Formation: Middle Triassic) and the spatiotemporal origins of Trilophosauridae

Foffa

Nesbitt

Kligman

et al. 2022

Journal of Vertebrate Paleontology

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Hwiccewyrm trispiculum gen. et sp. nov., a new leptopleuronine procolophonid from the Late Triassic of southwest England

Butler,

Meade,

Cleary

et al. 2023

The Anatomical Record

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The fissure fill localities of southwest England and South Wales are well‐known for preserving rich assemblages of predominantly small‐bodied Late Triassic to Early Jurassic tetrapods, but many aspects of these assemblages remain contentious. The age of the Late Triassic fissures is disputed, with some lines of argument suggesting a latest Triassic (Rhaetian) age, whereas other evidence suggests they may be as old as Carnian. The fissures have been hypothesized by some workers to have formed on an archipelago, with island effects invoked to explain aspects of the assemblages such as the abundance of small‐bodied species. Procolophonids were a successful group of Triassic parareptiles, best known from Early to early Late Triassic assemblages, but have only recently been described from one of the fissure fill sites (Ruthin) based upon fragmentary remains. Here, we describe new procolophonid specimens from another fissure (Cromhall) that represent at least six individuals of different sizes, with much of the skeleton represented including well‐preserved skull material. The Cromhall procolophonid shows strong similarities to Late Triassic procolophonids from Scotland, Brazil and North America, but both autapomorphies and a unique character combination demonstrate that it represents a new species, which we name as Hwiccewyrm trispiculum gen. et sp. nov. Phylogenetic analysis places Hwiccewyrm in a derived clade within Leptopleuroninae, together with Leptopleuron, Hypsognathus, and Soturnia. The largest specimens of Hwiccewyrm demonstrate a body size that is similar to Leptopleuron and Hypsognathus, supporting other recent work that has questioned the insular dwarfism hypothesis for the fissure fill assemblages.

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The redescription of Malerisaurus robinsonae (Archosauromorpha: Allokotosauria) from the Upper Triassic lower Maleri Formation, Pranhita‐Godavari Basin, India

Sengupta,

Ezcurra,

Bandyopadhyay

2024

The Anatomical Record

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Allokotosauria, a clade of non‐archosauriform archosauromorphs with a broad diversity of body plans, plays a crucial role in better understanding the evolutionary history of early diverging stem‐archosaurs. Here we provide a detailed redescription of Malerisaurus robinsonae, a malerisaurine allokotosaur from the middle Carnian—lowermost Norian lower Maleri Formation, Pranhita‐Godavari Basin, India. The new anatomical information available from recently discovered and well‐preserved skeletons of various allokotosaurs, such as Azendohsaurus madagaskarensis, Shringasaurus indicus, Puercosuchus traverorum, and Malerisaurus‐like taxa, and their comparison with Malerisaurus robinsonae enriches our understanding of the anatomy of this species. To reassess the phylogenetic relationships of Malerisaurus robinsonae, we revised its scorings and included eight additional allokotosaurian species to the already most comprehensive phylogenetic dataset focused on Permo‐Triassic archosauromorphs. We modified 70 scorings for Malerisaurus robinsonae and the new analysis recovered this species at the base of Malerisaurinae and this group as the earliest branch of Azendohsauridae. Pamelaria dolichotrachela is found as the earliest diverging non‐malerisaurine azendohsaurid and sister taxon to the Shringasaurus indicus + Azendohsaurus spp. clade. Trilophosaurid interrelationships are well resolved, with Teraterpeton hrynewichorum, Coelodontognathus ricovi, and Rutiotomodon tytthos as their successive earliest‐branching species. The position of Anisodontosaurus greeri as a sister taxon to Variodens inopinatus bolsters long ghost lineages in the Late Triassic trilophosaurid record. A disparity analysis of tooth crown morphology shows that Allokotosauria is the most disparate Permo‐Triassic archosauromorph clade, exploring the almost complete range of basic crown morphologies. Trilophosaurids occupy an area of the dental morphospace unique among archosauromorphs.

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A new Middle Triassic (Ladinian) trilophosaurid stem-archosaur from Germany increases diversity and temporal range of this clade

Cited by 8 publications

References 44 publications

New specimen and redescription of Anisodontosaurus greeri (Moenkopi Formation: Middle Triassic) and the spatiotemporal origins of Trilophosauridae

New specimen and redescription of Anisodontosaurus greeri (Moenkopi Formation: Middle Triassic) and the spatiotemporal origins of Trilophosauridae

Hwiccewyrm trispiculum gen. et sp. nov., a new leptopleuronine procolophonid from the Late Triassic of southwest England

The redescription of Malerisaurus robinsonae (Archosauromorpha: Allokotosauria) from the Upper Triassic lower Maleri Formation, Pranhita‐Godavari Basin, India

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