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Hi all, While this article unfortunately does not appear to be open-access, and I therefore don't actually have access to it myself even, the abstract and names associated with it seemed significant enough to share. Because, while greatly understudied, thalattosuchia, everybody's favourite clade of marine crocodiles, has just received a new phylogeny. One that introduces two new nomina - neothalattosuchia and euthalattosuchia - and the (presumably) tribal name of dakosaurina, as well as redefined the core characters of thalattosuchia as a whole. The origins of the clade in crocodylomorpha are also explored, though no resolution seems to have been found for this question. Overall, this seems a significant publication for marine reptile palaeobiology! Youg et al. (2024). The history, systematics, and nomenclature of Thalattosuchia (Archosauria: Crocodylomorpha). Zoological Journal of the Linnean Society.
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One for the (marine) crocodile specialist...
pachy-pleuro-whatnot-odon posted a topic in Questions & Answers
Hi everyone, Recently, while researching the morphology of machimosaurid crocodile teeth, I bumped into the below specimen, identified as Machimosaurus hugii (presumably based on its size). And although I can't confirm the specific name, I'm confident the referral to Machimosaurus is correct. When taking a closer look at the tooth's striations, however, I noticed not all of them actually run the whole apicobasal length of the tooth as I expected. And although some striations have undoubtedly been terminated and/or interrupted by wear, I was more genetically wondering if striations not running the full apicobasal length of the tooth is a know characteristic of crocodile teeth. For I'm only familiar with teeth that are either entirely smooth, or that have fine striations on one or both sides of the tooth, where only those striations that run into one of the tooth's carinae may be truncated before reaching the full apicobasal length of the tooth. That having been said, though, I can imagine crocodilian dental ornamentation being more varied, with different patterns of organisation in their striations, as Madzia (2016, A reappraisal of Polyptychodon (Plesiosauria) from the Cretaceous of England), in an annotation with his figure 8 illustrating pliosaurid tooth crown morphologies following Tarlo (1960) (reproduced below), observes that the teeth with the most striae, previously referred to Simolestes nowackianus, are now considered Machimosaurus nowackianus. And with the great variation of expression in striations on pliosaurian teeth, I don't think it would be such a leap to assume the same for this species of teleosaur... So, my question is: are striations on crocodilian teeth as variable as they are amongst pliosaurs? Can individual striae end prior to stretching the full apicobasal length of the tooth, and, if so, in which clades or under what conditions? Do crocodilian teeth exhibit patterns of striations of interchanging lengths (e.g., short-long-short)? Thanks for your help!- 14 replies
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Roughly two years ago, while investigating the identity of a marine reptile tooth said to have come from Lyme Regis, I got hinted about a spectacular new marine crocodile, much older than any other member of the thalattosuchian clade. This new species has finally been described: Turnersuchus hingleyae! Set outside the traditional subgroupings of teleosauroidea and metriorhynchoidea, this newly described species has major implications for the evolutionary relationships between thalattosuchians and other crocodylomorphs. Wilberg, Godoy, Griffiths, Turner & Benson, 2023. A new early diverging thalattosuchian (Crocodylomorpha) from the Early Jurassic (Pliensbachian) of Dorset, U.K. and implications for the origin and evolution of the group. Art by Júlia d'Oliveira (source)
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A new fossil crocodylomorph-related paper is now available online: Johnson, M. M., Young, M. T., and Brusatte, S. L. (2020). Emptying the wastebasket: a historical and taxonomic revision of the Jurassic crocodylomorph Steneosaurus. Zoological Journal of the Linnean Society 189 (2): 428–448. https://doi.org/10.1093%2Fzoolinnean%2Fzlaa027 Michela Johnson and colleagues restrict Steneosaurus to the type species S. rostromajor, and make the teleosauroid snout MNHN 8900 the S. rostromajor lectotype (the skull fragment MNHN 8753 was later recognized as belonging to the metriorhynchid Metriorhynchus superciliosus) and they correctly recognize, as I had tacitly noticed, that Eudes-Deslongchamps (1867-1869) made an error in declaring that the Bathonian-age teleosauroid 'Steneosaurus' megistorhynchus best fulfilled the function of Steneosaurus type species not knowing that megistorhynchus was not an originally included nominal species of Steneosaurus. A Ph.D thesis written by Johnson last year regarding teleosauroids is available at this link: https://era.ed.ac.uk/handle/1842/36656 (Chapter 4 of the thesis by Johnson resurrects Macrospondylus for S. bollensis from the Toarcian of Europe and coins new genera for several taxa placed in Steneosaurus while revalidating Aeolodon and Sericodon, but I wouldn't disclose the names of the new genera until Chapter 4 is published, because doing so would be tantamount to stealing my thunder) In any case, Johnson and colleagues at long last figured out the concept of what the original Steneosaurus is, and given that Bathysuchus, Aeolodon, and Sericodon are much younger than the Steneosaurus type species, whereas Macrospondylus and a few other Early Jurassic teleosauroids are much older than rostromajor, it is apparent that the past assignment of many teleosauroid species to Steneosaurus is a historical accident and not reflective of biology reality, because Lemmysuchus is closer to Machimosaurus than to Steneosaurus or 'S.' edwardsi.
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First off: happy new year, everyone! Blezingeria ichthyospondylus is an enigmatic marine reptile from the Ladinian-stage Triassic, Upper Muschelkalk of Baden-Württemberg in southwestern Germany, first discovered in Crailsheim. Although various material has been referred to the species through time, its affiliation remains unclear. Initially described as nothosaurian and later as cymbospondylid ichthyosaurian, it has most recently been classed as thalattosaurian. Fossilworks, however, still defines it as cymbospondylid, whereas Muschelkalk.eu classifies it as an Eosuchian. Below is an overview of some of the material that has been attributed to the species: Source: Wikipedia Vertebrae & humerus. Source: Wikimedia Commons Source: Muschelkalkmuseum Ingelfingen Vertebrae & scapula. Source: Muschelkalk.eu As you can see, the vertebrae are amphicoelous, just like those of ichthyosaurians. Though, contrary to in ichthyosaurs, the neural arch in B. ichthyospondylus is attached to the vertebral body. Scapulae and pubis bones are also highly reminiscent of those found in ichthyosaurs. All this, of course, is not to say that there were no other early marine reptiles with amphicoelous vertebrae - such as those of Placodus gigas figured below, for example: Sources: online vendor & figure 13 from Diedrich, 2013. Review of the Middle Jurassic "sea cow" Placodus gigas (Reptilia) in Pangea's shallow marine macroalgae meadows of Europe At the same time, and in the same area, true ichthyosaurs were also already around, and already had characteristic their amphicoelous vertebrae free of neural arch, including such species as Cymbospondylus sp., Phantomosaurus sp. - which, according to Fossilworks, are sister taxa to B. ichthyospondylus - and, possibly, Pessosaurus sp., to which the below Middle Triassic vertebra has tentatively been ascribed: Source: Muschelkalkmuseum Ingelfingen The most comprehensive overview of Blezingeria ichthyospondylus material, however, comes from Diedrich, 2015. The vertebrates from the Lower Ladinian (Middle Triassic) bonebed of Lamerden (Germany) as palaeoenvironment indicators in the Germanic Basin (figure 9): Looking at the above image, the similarities with ichthyosaur skeletal material is indeed no longer obvious, which is reflected in the reconstruction, though there are still similarities to be found in the bone morphology of B. ichthyospondylus' fibula (no. 11 in the image above) and the Utatsusaurus sp. (primitive ichthyosaur) paddle in the diagram below: Figure 4 from Motani, 2005. Evolution of Fish-Shaped Reptiles (reptilia: Ichthyopterygia) in Their Physical Environments and Constraints The only cladistic data I can find on the interrelationships between thalattosauria, ichthyopterygia and sauropterygia, however, comes from the Pterosaur Heresies and Reptile Evolution - and, therefore, doesn't derive from the most reliable sources - lacks documented source references, and seems, at least in part, internally contradictory: Not having read Diedrich 2015 yet, my first question is, is there any more information on Blezingeria ichthyospondylus out there on easily accessible media (i.e., the internet, preferably open access)? Does anyone on TFF know about this species, and what is there to know about this species? Where does it fit in phylogenetically, and how does this relate to the other clades of marine reptile? Is there any merit to the above cladograms? Thanks for your help!
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Marine crocodile vertebrae: what's the difference?
pachy-pleuro-whatnot-odon posted a topic in Questions & Answers
Hi all, I recently took some more interest in crocodile vertebrae, an area that I haven't really touched on before. Now I already knew that the vertebrae of marine crocodiles differ from those of more terrestrial species as Thalattosuchia have platycoelous vertebral centrums, whereas other crocodylomorphs have procoelous vertebrae. Within Thalattosuchia, however, the two major branches superficially (at least) seem to have rather similar "waisted" vertebrae. So, what I was wondering about was how one can tell Metriorhynchid vertebrae apart from Teleosaurid ones. Anyone here that could help me with that? Anyway, thanks in advance for your help! -
A very cool article and let the intro speak for itself To most people, crocodilians are large-bodied carnivores that have been unchanged since the age of the dinosaurs. However, during their 230 million-year history, modern crocodilians and their extinct relatives evolved a stunning diversity of body plans, with many looking very different from those alive today (crocodiles, alligators, caimans and gharials). If you are interested in further readings lots of suggestions at the end of the article. https://www.palaeontologyonline.com/articles/2018/fossil-focus-thalattosuchia/
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