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The Jurassic period was a time of major diversification for Mesozoic marine reptiles, including Ichthyosauria, Plesiosauria and thalattosuchian Crocodylomorpha. The latter originated in the Early Jurassic and thrived during the Late Jurassic. Unfortunately, the Middle Jurassic, a crucial time in their evolution, has a poor fossil record. Here, we document the first evidence of macrophagous/durophagous Machimosaurini-tribe teleosauroid thalattosuchians from the late Bajocian (ca 169 Ma) in the form of three robust tooth crowns with conical blunt shapes and anastomosed pattern of thick enamel ridges towards the apex, associated with the skeleton of a large ichthyosaur lacking preserved tooth crowns. The tooth crowns were found on the posterior section of the lower jaw (left angular), a lacrimal and the axis neural arch of the ichthyosaur. In addition, some of the distal sections of the posterior dorsal ribs of the ichthyosaur skeleton exhibit rounded bite marks and some elongated furrows that fit in size and shape with the Machimosaurini teeth. These marks, together with the absence of healing in the rib bone are interpreted here as the indicators of peri- to post-mortem scavenging by a Machimosaurini teleosauroid after the large ichthyosaur carcass settled on the floor of a shallow ocean.

The study of how organisms grow is a fundamental aspect of palaeontology. Growth in teleosauroids is poorly understood and little studied, especially in an ontogenetic sense. We investigate growth rates of the most common and abundant teleosauroid, Macrospondylus bollensis, in which a large sample of multiple body sizes is available from the Posidonienschiefer Formation (Posidonia Shale) of southwestern Germany. We perform linear regression analyses on 62 specimens of Macrospondylus (16 juveniles, 7 subadults and 39 adults) using 21 cranial and postcranial measurements. Our results show that juvenile, subadult and adult individuals have near‐isometric or isometric growth throughout much of the body. Notably, we find that in Macrospondylus: (1) the femur grows at a faster rate than the skull and hindlimb zeugopodium; (2) the forelimb and hindlimb grow at the same rate; and (3) there is distinct ontogenetic signal in the growth of the orbit and supratemporal fenestra. We also find that limb scaling in Macrospondylus is somewhat comparable to that seen in the extant gavialids Gavialis gangeticus and Tomistoma schlegelii. Last, we examine evolutionary allometry in skull length relative to body size in Crocodylomorpha using femoral length as a proxy, which shows a near‐isometric trend. Non‐thalattosuchian crocodylomorphs (with the exception of one pholidosaurid and one dryosaurid taxon) are differentiated from thalattosuchians due to their shorter skulls, as previously suggested, but the scaling relationship with femur length remains unchanged. [ABSTRACT FROM AUTHOR]

Secondarily marine tetrapod lineages have independently evolved osmoregulatory adaptations for life in salt water but inferring physiological changes in extinct marine tetrapods is difficult. The Mesozoic crocodylomorph clade Thalattosuchia is unique in having both direct evidence from natural endocasts and several proposed osteological correlates for salt exocrine glands. Here, we investigate salt gland evolution in thalattosuchians by creating endocranial reconstructions from CT scans of eight taxa (one basal thalattosuchian, one teleosauroid, two basal metriorhynchoids and four metriorhynchids) and four outgroups (three extant crocodylians and the basal crocodyliform Protosuchus) to identify salt gland osteological correlates. All metriorhynchoids show dorsolateral nasal cavity expansions corresponding to the location of nasal salt glands in natural casts, but smaller expansions in teleosauroids correspond more with the cartilaginous nasal capsule. The different sizes of these expansions suggest the following evolutionary sequence: (1) plesiomorphically small glands present in semi-aquatic teleosauroids draining through the nasal vestibule; (2) moderately sized glands in the basalmost metriorhynchoid Pelagosaurus ; and (3) hypertrophied glands in the clade comprising Eoneustes and metriorhynchids, with a pre-orbital fenestra providing a novel exit for salt drainage. The large gland size inferred from basal metriorhynchoids indicates advanced osmoregulation occurred while metriorhynchoids were semi-aquatic. This pattern does not precisely fit into current models of physiological evolution in marine tetrapods and suggests a unique sequence of changes as thalattosuchians transitioned from land to sea. [ABSTRACT FROM AUTHOR]

Throughout the Jurassic, a plethora of marine reptiles dominated ocean waters, including ichthyosaurs, plesiosaurs and thalattosuchian crocodylomorphs. These Jurassic ecosystems were characterized by high niche partitioning and spatial variation in dietary ecology. However, while the ecological diversity of many marine reptile lineages is well known, the overall ecological diversification of Teleosauroidea (one of the two major groups within thalattosuchian crocodylomorphs) has never been explored. Teleosauroids were previously deemed to have a morphologically conservative body plan; however, they were in actuality morphofunctionally more diverse than previously thought. Here we investigate the ecology and feeding specializations of teleosauroids, using morphological and functional cranio‐dental characteristics. We assembled the most comprehensive dataset to date of teleosauroid taxa (approximately 20 species) and ran a series of principal component analyses (PC) to categorize them into various feeding ecomorphotypes based on 17 dental characteristics (38 specimens) and 16 functionally significant mandibular characters (18 specimens). The results were examined in conjunction with a comprehensive thalattosuchian phylogeny (153 taxa and 502 characters) to evaluate macroevolutionary patterns and significant ecological shifts. Machimosaurids display a well‐developed ecological shift from: (1) slender, pointed tooth apices and an elongate gracile mandible; to (2) more robust, pointed teeth with a slightly deeper mandible; and finally, (3) rounded teeth and a deep‐set, shortened mandible with enlarged musculature. Overall, there is limited mandibular functional variability in teleosaurids and machimosaurids, despite differing cranial morphologies and habitat preferences in certain taxa. This suggests a narrow feeding ecological divide between teleosaurids and machimosaurids. Resource partitioning was primarily related to snout and skull length as well as habitat; only twice did teleosauroids manage to make a major evolutionary leap to feed distinctly differently, with only the derived machimosaurines successfully radiating into new feeding ecologies. [ABSTRACT FROM AUTHOR]

We report the first definite specimen of a thalattosuchian crocodylomorph from the Portland Stone Formation of England. This specimen (an isolated tooth crown) can be referred to the teleosauroid genus Machimosaurus based on its conical shape, distinctive enamel ornamentation and lack of carinae. Understanding the faunal composition of the Portland Stone Formation is key to elucidating the distinct shift in crocodylomorph taxa that occurred during the Tithonian-to-Berriasian in Europe. One of the most striking aspects of this faunal shift is the hypothesised extinction of Teleosauroidea in Europe. The presence of Machimosaurus in the Portland Stone Formation supports the hypothesis that the localised marine regression in Europe at the Jurassic–Cretaceous boundary, and the resultant habitat loss, contributed to the absence of teleosauroids in Europe during the Berriasian. However, the fossil record of thalattosuchians during the Cretaceous is notorious scarce. We review the purported Cretaceous record of teleosauroids, and agree that closer to the equator this clade survived for at least 20 million years after the Jurassic–Cretaceous boundary. [ABSTRACT FROM AUTHOR]

The genus Mystriosaurus, established by Kaup in 1834, was one of the first thalattosuchian genera to be named. The holotype, an incomplete skull from the lower Toarcian Posidonienschiefer Formation of Altdorf (Bavaria, southern Germany), is poorly known with a convoluted taxonomic history. For the past 60 years, Mystriosaurus has been considered a subjective junior synonym of Steneosaurus. However, our reassessment of the Mystriosaurus laurillardi holotype demonstrates that it is a distinct and valid taxon. Moreover, we find the holotype of “Steneosaurus” brevior, an almost complete skull from the lower Toarcian Whitby Mudstone Formation of Whitby (Yorkshire, UK), to be a subjective junior synonym of M. laurillardi. Mystriosaurus is diagnosed in having: a heavily and extensively ornamented skull; large and numerous neurovascular foramina on the premaxillae, maxillae and dentaries; anteriorly oriented external nares; and four teeth per premaxilla. Our phylogenetic analyses reveal M. laurillardi to be distantly related to Steneosaurus bollensis, supporting our contention that they are different taxa. Interestingly, our analyses hint that Mystriosaurus may be more closely related to the Chinese teleosauroid (previously known as Peipehsuchus) than any European form.

Teleosauroidea was a clade of ancient crocodylomorphs that were a key element of coastal marine environments during the Jurassic. Despite a 300-year research history and a recent renaissance in the study of their morphology and taxonomy, macroevolutionary studies of teleosauroids are currently limited by our poor understanding of their phylogenetic interrelationships. One major problem is the genus Steneosaurus, a wastebasket taxon recovered as paraphyletic or polyphyletic in phylogenetic analyses. We constructed a newly updated phylogenetic data matrix containing 153 taxa (27 teleosauroids, eight of which were newly added) and 502 characters, which we analysed under maximum parsimony using TNT 1.5 (weighted and unweighted analyses) and Bayesian inference using MrBayes v3.2.6 (standard, gamma and variation). The resulting topologies were then analysed to generate comprehensive higher-level phylogenetic hypotheses of teleosauroids and shed light on species-level interrelationships within the clade. The results from our parsimony and Bayesian analyses are largely consistent. Two large subclades within Teleosauroidea are recovered, and they are morphologically, ecologically and biogeographically distinct from one another. Based on comparative anatomical and phylogenetic results, we propose the following major taxonomic revisions to Teleosauroidea: (1) redefining Teleosauridae; (2) introducing one new family and three new subfamilies; (3) the resurrection of three historical genera; and (4) erecting seven new generic names and one new species name. The phylogeny infers that the Laurasian subclade was more phenotypically plastic overall than the Sub-Boreal-Gondwanan subclade. The proposed phylogeny shows that teleosauroids were more diverse than previously thought, in terms of morphology, ecology, dispersal and abundance, and that they represented some of the most successful crocodylomorphs during the Jurassic.

Teleosauroidea is a clade of ancient crocodylomorphs that were integral components of coastal marine environments throughout the Jurassic. For nearly two centuries, one of the most familiar genera of teleosauroids has been Steneosaurus , encompassing nearly every teleosauroid species at some point. However, no type species has been designated for Steneosaurus under ICZN Code rules; the type specimen of the presumed type species S. rostromajor Geoffroy Saint-Hilaire, 1825 (MNHN.RJN 134c-d) is a chimera that has been largely neglected in the literature. Moreover, there is confusion as to which teleosauroid species it pertains to, and the genus Steneosaurus is often recovered as paraphyletic or polyphyletic in phylogenetic analyses. As such, the validity of Steneosaurus is uncertain. Here we formally designate S. rostromajor as the type species of Steneosaurus , designate a lectotype and re-evaluate MNHN.RJN 134c-d. We compare it with several well-known teleosauroids, including Lemmysuchus and ' S.' edwardsi. Due to lack of autapomorphic characters, poor preservation and a tortured taxonomic history, we find MNHN.RJN 134c-d to be an undiagnostic and unreliable specimen. Thus, we consider S. rostromajor as a nomen dubium and propose that the genus Steneosaurus is undiagnostic. This has profound implications for teleosauroid phylogenetics, which we will clarify in an upcoming paper. [ABSTRACT FROM AUTHOR]

Teleosauroidea was a clade of successful, morphologically diverse, ancient crocodylomorphs that were integral in coastal marine/lagoonal environments during the Jurassic. Within Teleosauroidea, the macrophagous/durophagous tribe Machimosaurini evolved specialized feeding strategies (e.g. hypertrophied jaw musculature and blunt, heavily ornamented dentition) and large body sizes (> 7 m), becoming an important component of Middle and Late Jurassic ecosystems. These ocean-dwelling giants are well known from the Callovian (Lemmysuchus) of Europe and the UK, and from the Kimmeridgian–Tithonian (Machimosaurus) of Europe and northern Africa. There are reports of fragmentary machimosaurin material from the Bathonian of Africa, but the overall Bathonian teleosauroid material is poorly understood. While multiple specimens were described during the 19th and 20th centuries, little research has been done since. Here we re-describe two historically important Bathonian species from near Oxford, UK. We demonstrate that both ' Steneosaurus ' larteti and ' Steneosaurus ' boutilieri are valid taxa and we establish neotypes for both species and two new genera, Deslongchampsina and Yvridiosuchus. Our cladistic analysis finds Yvridiosuchus boutilieri as a basal member of Machimosaurini and Deslongchampsina larteti to be closely related to Steneosaurus heberti. Interestingly, four distinct teleosauroid ecomorphotypes are present in the Bathonian of Europe and teleosauroid ecomorphological diversity continued throughout the Callovian and Kimmeridgian/Tithonian in Europe and England. [ABSTRACT FROM AUTHOR]

Teleosauroids were a successful group of semi-aquatic crocodylomorphs that were an integral part of coastal marine/lagoonal faunas during the Jurassic. Their fossil record suggests that the group declined in diversity and abundance in deep water deposits during the Late Jurassic. One of the few known teleosauroid species from the deeper water horizons of the well-known Kimmeridge Clay Formation is ‘Teleosaurus’ megarhinus Hulke, 1871, a poorly studied, gracile longirostrine form. The holotype is an incomplete snout from the Aulacostephanus autissiodorensis Sub-Boreal ammonite Zone of Kimmeridge, England. The only other referred specimen is an almost complete skull from the slightly older A. eudoxus Sub-Boreal ammonite Zone of Quercy, France. Recently, the validity of this species has been called into question. Here we re-describe the holotype as well as the referred French specimen and another incomplete teleosauroid, DORCM G.05067i-v (an anterior rostrum with three osteoderms and an isolated tooth crown), from the same horizon and locality as the holotype. We demonstrate that all specimens are referable to ‘Teleosaurus’ megarhinus and that the species is indeed a valid taxon, which we assign to a new monotypic genus, Bathysuchus. In our phylogenetic analysis, the latest iteration of the ongoing Crocodylomorph SuperMatrix Project, Bathysuchus megarhinus is found as sister taxon to Aeolodon priscus within a subclade containing Mycterosuchus nasutus and Teleosaurus cadomensis. Notably Bathysuchus has an extreme reduction in dermatocranial ornamentation and osteoderm size, thickness and ornamentation. These features are mirrored in Aeolodon priscus, a species with a well-preserved post-cranial skeleton and a similar shallow and inconspicuous dermal ornamentation. Based on these morphological features, and sedimentological evidence, we hypothesise that the Bathysuchus + Aeolodon clade is the first known teleosauroid lineage that evolved a more pelagic lifestyle.

Teleosauroids were a clade of semi-marine crocodylomorphs that attained near-global distribution during the Jurassic Period. They were particularly common during the Toarcian (Early Jurassic) and are well documented throughout the UK and Germany. However, Toarcian teleosauroids discovered in Luxembourg have been little studied and rarely discussed in the scientific literature. Here we present a comprehensive catalogue of Luxembourg thalattosuchian specimens, including nine teleosauroids (all from the Toarcian) and five Thalattosuchia indeterminate (four from the Toarcian and one from the Bajocian), many of which are noted in the literature for the first time. We describe these specimens and identify two distinct genera (Steneosaurus and Platysuchus) as present in the sample as well as three, or possibly four, distinct species. This represents a high diversity of teleosauroid taxa (both common and rare forms) from the Toarcian rarely seen elsewhere in the world. [ABSTRACT FROM AUTHOR]

The geographic origins and distributional patterns of Gondwanan teleosauroids during the Jurassic have been fiercely debated over many years. Unlike the rich thalattosuchian fossil record from Laurasia, teleosauroids described from Gondwanan ecosystems are relatively scarce. Most of the known occurrences consist of isolated and fragmentary bones collected in Madagascar, Morocco, Tunisia, India, and Ethiopia. Nevertheless, these specimens, although fragmentary, have provided substantial information for assessing the evolutionary scenarios of multiple teleosauroid lineages and have shown that certain teleosauroid taxa were widespread rather than endemic to Western Europe. Here, a partial skeleton of a teleosauroid crocodylomorph is described. It was found in the late Middle Jurassic (Callovian) deposits of southeastern Tunisia by a team of French and Tunisian paleontologists; however, it has not been thoroughly studied at both macro- and microscopic scale until now. The new specimen is composed of an incomplete symphyseal portion of a lower jaw in addition to isolated teeth, osteoderms (both dorsal and ventral), thoracic and caudal vertebrae, and several thoracic ribs. The specimen has several morphological characters that are reminiscent of longirostrine teleosauroids. Due to the total absence of other cranial bones, as well as the pectoral and pelvic girdles, the specimen is not diagnostic to the generic level. However, these new remains represent the youngest ascertained occurrence of a definitive non-machimosaurin teleosauroid in Africa, provide additional insights into the geographic distribution of Thalattosuchia, and raise once again the question whether the origins of this clade were Gondwanan or Laurasian. [ABSTRACT FROM AUTHOR]

The genus Mystriosaurus, established by Kaup in 1834, was one of the first thalattosuchian genera to be named. The holotype, an incomplete skull from the lower Toarcian Posidonienschiefer Formation of Altdorf (Bavaria, southern Germany), is poorly known with a convoluted taxonomic history. For the past 60 years, Mystriosaurus has been considered a subjective junior synonym of Steneosaurus. However, our reassessment of the Mystriosaurus laurillardi holotype demonstrates that it is a distinct and valid taxon. Moreover, we find the holotype of "Steneosaurus" brevior, an almost complete skull from the lower Toarcian Whitby Mudstone Formation of Whitby (Yorkshire, UK), to be a subjective junior synonym of M. laurillardi. Mystriosaurus is diagnosed in having: a heavily and extensively ornamented skull; large and numerous neurovascular foramina on the premaxillae, maxillae and dentaries; anteriorly oriented external nares; and four teeth per premaxilla. Our phylogenetic analyses reveal M. laurillardi to be distantly related to Steneosaurus bollensis, supporting our contention that they are different taxa. Interestingly, our analyses hint that Mystriosaurus may be more closely related to the Chinese teleosauroid (previously known as Peipehsuchus) than any European form. [ABSTRACT FROM AUTHOR]

Teleosauroids were a successful group of semi-aquatic crocodylomorphs that were an integral part of coastal marine/lagoonal faunas during the Jurassic. Their fossil record suggests that the group declined in diversity and abundance in deep water deposits during the Late Jurassic. One of the few known teleosauroid species from the deeper water horizons of the well-known Kimmeridge Clay Formation is 'Teleosaurus' megarhinus Hulke, 1871, a poorly studied, gracile longirostrine form. The holotype is an incomplete snout from the Aulacostephanus autissiodorensis Sub-Boreal ammonite Zone of Kimmeridge, England. The only other referred specimen is an almost complete skull from the slightly older A. eudoxus Sub-Boreal ammonite Zone of Quercy, France. Recently, the validity of this species has been called into question. Here we redescribe the holotype as well as the referred French specimen and another incomplete teleosauroid, DORCM G.05067i-v (an anterior rostrum with three osteoderms and an isolated tooth crown), from the same horizon and locality as the holotype. We demonstrate that all specimens are referable to 'Teleosaurus' megarhinus and that the species is indeed a valid taxon, which we assign to a new monotypic genus, Bathysuchus. In our phylogenetic analysis, the latest iteration of the ongoing Crocodylomorph SuperMatrix Project, Bathysuchus megarhinus is found as sister taxon to Aeolodon priscus within a subclade containing Mycterosuchus nasutus and Teleosaurus cadomensis. Notably Bathysuchus has an extreme reduction in dermatocranial ornamentation and osteoderm size, thickness and ornamentation. These features are mirrored in Aeolodon priscus, a species with a well-preserved post-cranial skeleton and a similar shallow and inconspicuous dermal ornamentation. Based on these morphological features, and sedimentological evidence, we hypothesise that the Bathysuchus + Aeolodon clade is the first known teleosauroid lineage that evolved a more pelagic lifestyle. [ABSTRACT FROM AUTHOR]

The Chaara cave is a natural karst cavity, located in the Middle Atlas of Morocco, shaped by water over millions of years. It is an active underground river, containing several galleries spread over two floors. The exploration of this cave led to the discovery of a teleosauroid crocodylomorph at the level of the dolomitic limestone of the earliest Jurassic (Hettangian-Sinemurian). A detailed paleontological study of the specimen's skull and nested mandible was carried out based on combinations of key morphological characteristics, but to the material does not allow an advanced assignment the Moroccan specimen to a genus level. A geological, topographical, and photogrammetric study was also carried out for the development of this discovery, which is a first in the region. A 3D model of the findings was made to reconstruct this finding. The extraction of the fossil is not possible, a molding was made to keep its imprint and allow its development as a paleontological heritage. Most known teleosauroids have been recovered from Europe, and they are particularly rare outside of Europe. In Africa, they are known from several localities in Tunisia, Ethiopia, Morocco and Madagascar. Most of the remains are fragmentary and only three species have been named , Machimosaurus rex , Machimosaurus nowackianus and Steneosaurus baroni. The temporal and geographical appearance of the first thalattosuchian in Africa remains highly discussed and not well understood thus, the discovery of new remains in Morocco in the dolomitic limestone of the earliest Jurassic is of great interest, as it represents the oldest known African thalattosuchian. It demonstrates that the geographical origin of thalattosuchians cannot currently be assessed because they were widely distributed as soon as the earliest Jurassic. • Discovery of the Moroccan Teleosauroid and its Lower Liassic age. • Geological, topographical, and photogrammetric study. • Paleontological study of the skull and mandible of the teleosauroid. • Paleo geographical distribution of thalattosuchians in the lower Lias. • Natural paleontological heritage of Tazzeka National Park. [ABSTRACT FROM AUTHOR]

Marine crocodylomorphs were particularly abundant in Europe during the Middle Jurassic, but were very scarce in Africa. New finds of thalattosuchian cranial remains in Morocco suggest that this scarcity is probably related to poor sampling rather than original diversity. These remains pertain to the coastal thalattosuchians, the teleosauroids, and particularly to the clade grouping the blunt-toothed ' Steneosaurus' obtusidens and the genus Machimosaurus. A new tribe is erected grouping these two taxa: Machimosaurini. Until now the machimosaurins have been known from the middle Callovian. The new material extends the presence of this group further back to the lower Bathonian, nearly 5 myr earlier. The machimosaurins are the only teleosauroid group that has been recently reviewed, and the difference between the revised diversity provided herein and that previously reported is large. A review of other teleosauroids and clear establishment of their phylogenetic relationships are also likely to have considerable impact on their observed diversity. So, until a complete review of the teleosauroids is carried out, the results of crocodylomorph diversity analyses should be treated with caution. [ABSTRACT FROM AUTHOR]