The Late Triassic Timescale

Lucas, Spencer G.

doi:10.1007/978-3-319-68009-5_1

Cited by 11 publications

(5 citation statements)

References 66 publications

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“…The Permian-Triassic (P-T) mass extinction profoundly influenced the evolutionary history of most taxa that survived the P-T event [ 1 , 2 ]. Sauropterygia are a particularly successful group of secondarily marine sauropsids of which the oldest recognized fossils date back to the Spathian sub-stage of the Olenekian [ 3 , 4 ], about 5 million years after the P-T mass extinction [ 1 ]. These initially small- to medium-bodied predators exhibited rapid dispersal in the newly formed epicontinental Muschelkalk Sea and along the shallow marine margins of the Tethyan realm [ 5 ] in a highly competitive arena shared with a diverse variety of other secondarily marine reptile taxa [ 1 ].…”

Section: Introductionmentioning

confidence: 99%

Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia

Voeten¹,

Reich²,

Araújo³

et al. 2018

PLoS ONE

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Nothosaurs form a subclade of the secondarily marine Sauropterygia that was well represented in late Early to early Late Triassic marine ecosystems. Here we present and discuss the internal skull anatomy of the small piscivorous nothosaur Nothosaurus marchicus from coastal to shallow marine Lower Muschelkalk deposits (Anisian) of Winterswijk, The Netherlands, which represents the oldest sauropterygian endocast visualized to date. The cranial endocast is only partially encapsulated by ossified braincase elements. Cranial flattening and lateral constriction by hypertrophied temporal musculature grant the brain a straight, tubular geometry that lacks particularly well-developed cerebral lobes but does potentially involve distinguishable optic lobes, suggesting vision may have represented an important sense during life. Despite large orbit size, the circuitous muscular pathway linking the basisphenoidal and orbital regions indicates poor oculomotor performance. This suggests a rather fixed ocular orientation, although eye placement and neck manoeuvrability could have enabled binocular if not stereoscopic vision. The proportionally large dorsal projection of the braincase endocast towards the well-developed pineal foramen advocates substantial dependence on the corresponding pineal system in vivo. Structures corroborating keen olfactory or acoustic senses were not identified. The likely atrophied vomeronasal organ argues against the presence of a forked tongue in Nothosaurus, and the relative positioning of external and internal nares contrasts respiratory configurations proposed for pistosauroid sauropterygians. The antorbital domain furthermore accommodates a putative rostral sensory plexus and pronounced lateral nasal glands that were likely exapted as salt glands. Previously proposed nothosaurian ‘foramina eustachii’ arose from architectural constraints on braincase development rather than representing functional foramina. Several modifications to brain shape and accessory organs were achieved through heterochronic development of the cranium, particularly the braincase. In summary, the cranium of Nothosaurus marchicus reflects important physiological and neurosensory adaptations that enabled the group’s explosive invasion of shallow marine habitats in the late Early Triassic.

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Section: Introductionmentioning

confidence: 99%

Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia

Voeten¹,

Reich²,

Araújo³

et al. 2018

PLoS ONE

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“…Sedimentological work within the Upper Karoo Group of the MZB has established a progressive shift in depositional environments through time from alluvial fan and braidplain deposits, through the fluvio-lacustrine and sheet-flood systems to fluvio-aeolian deposits. In combination with the biostratigraphical record, the Upper Karoo Group of the MZB exhibits the same long-term climatic trends as the Stormberg Group of the MKB (Smith & Kitching, 1997;Bordy et al 2004;Sciscio & Bordy, 2016) and the Triassic globally (Lucas, 2018), with temperate, humid regimes succeeded by increasingly arid climates.…”

Section: A Reconstructing the Palaeoenvironments Of The Fossiliferous Sitesmentioning

confidence: 82%

“…In recent years, the true age of South Africa's Early-Middle Triassic record, which plays a central role in global tetrapod biostratigraphy (Lucas, 1998), has been called into question by SHRIMP isotope dilutionthermal ionization mass spectrometry (ID-TIMS) dates retrieved from the Gondwanan record in Argentina (Ottone et al 2014). However, these ages are disputed (see Lucas, 2018).…”

Section: B Palaeontological Diversity and Proposed Age Relationshipsmentioning

confidence: 99%

Sedimentology and palaeontology of the Upper Karoo Group in the Mid-Zambezi Basin, Zimbabwe: new localities and their implications for interbasinal correlation

et al. 2020

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The Triassic–Jurassic Upper Karoo Group of the Mid-Zambezi Basin (MZB; Zimbabwe) includes a thick succession of terrestrial sediments with high palaeontological potential that has been neglected since the 1970s. Here, we review the Upper Karoo Group stratigraphy, present detailed sedimentological work and identify new vertebrate-bearing sites at several measured sections along the southern shore of Lake Kariba. These fossil-bearing sites fall within the Pebbly Arkose and Forest Sandstone formations, and are the first to be recorded from the region since the discovery of Vulcanodon karibaensis nearly 50 years ago. The unique and diverse assemblage of aquatic and terrestrial fauna reported includes phytosaurs, metoposaurid amphibians, lungfish, non-dinosaurian archosauromorphs and non-sauropod sauropodomorph dinosaurs. This improvement of Upper Karoo Group biostratigraphy is important in refining its temporal resolution, and impacts both regional and global studies. Finally, the new fossil sites demonstrate the palaeontological importance of the MZB and its role in providing a holistic understanding of early Mesozoic ecosystems in southern Gondwana.

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“…The temporal limits of the Norian indeed vary according to the authors: either 220–208.5 Ma (‘short Norian’ hypothesis of Muttoni et al . ; Lucas ; Lucas & Tanner ) or 227–208.5 Ma (‘long Norian’ hypothesis according to Ogg et al . ).…”

Section: Discussionmentioning

confidence: 99%

Redescription of Arganasaurus (Metoposaurus) azerouali (Dutuit) comb. nov. from the Upper Triassic of the Argana Basin (Morocco), and the first phylogenetic analysis of the Metoposauridae (Amphibia, Temnospondyli)

Buffa

Steyer

2019

Papers in Palaeontology

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A systematic revision of the temnospondyl 'Metoposaurus' azerouali Dutuit from the Late Triassic of the Argana Basin (Western High Atlas, Morocco) is presented. The type material is redescribed in detail, and a preliminary phylogenetic analysisthe first one dealing with all metoposaurid speciesis also conducted in order to test its position within the Metoposauridae. Our analysis places 'Metoposaurus' azerouali as sister-taxon to Arganasaurus lyazidi in a robust clade supported by two unambiguous synapomorphies (bulge-like tabular horn and exoccipital process visible in dorsal view) and two ambiguous synapomorphies (cultriform process of uniform width and subtriangular posterior Meckelian fenestra). We therefore propose the new combination Arganasaurus azerouali comb. nov. for the species 'M.' azerouali. Our analysis also confirms that the central Laurasian genus Metoposaurus is monophyletic but not the genus Koskinonodon, which deserves its own systematic revision. By consequent, the Late Triassic rich vertebrate fauna from the Argana Basin comprises the metoposauroid Almasaurus habazzi, the basal metoposaurid Dutuitosaurus ouazzoui, and the genus Arganasaurus which is represented by the type species A. lyazidi and A. azerouali comb. nov. Combined with the stratigraphical and geographical occurrences of the taxa, our phylogenetic analysis suggests that metoposaurids may have appeared during the Longobardian (late Ladinian) in central Pangea. Their diversification may be linked to the Carnian Pluvial Episode. At least, their extinction may have occurred during the Rhaetian because of the aridification of the climate and/or competition with amniotes.

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The Late Triassic Timescale

Cited by 11 publications

References 66 publications

Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia

Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia

Sedimentology and palaeontology of the Upper Karoo Group in the Mid-Zambezi Basin, Zimbabwe: new localities and their implications for interbasinal correlation

Redescription of Arganasaurus (Metoposaurus) azerouali (Dutuit) comb. nov. from the Upper Triassic of the Argana Basin (Morocco), and the first phylogenetic analysis of the Metoposauridae (Amphibia, Temnospondyli)

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