[Paleontology • 2026] Indosinosuchus peninsularensis • A new teleosaurid (Crocodylomorpha: Thalattosuchia) from the Sibumasu Terrane of Southeast Asia and A Taxonomic Reassessment of Indosinosuchus

 

Indosinosuchus peninsularensis 

Lauprasert, Nilpanapan, Martin, Claude, Kamonlak Wongko, Kantanat Trakunweerayut, Dobutr, Manitkoon, Bhuttarach & Nonsrirach, 2026

DOI: doi.org/10.7717/peerj.20944  

 facebook.com/Lauprasert

Abstract 

We describe teleosaurid remains from the Middle to Upper Jurassic Khlong Min Formation at Ban Nam Pun in southern Thailand and define Indosinosuchus peninsularensis sp. nov. This new species is diagnosed by a unique combination of cranial and postcranial features, including the nasal reaching anteriorly at the level of the 18th maxillary alveolus, absence of an incisive foramen, oval-shaped external nares, and broad ornamented osteoderms. Phylogenetic analysis positions I. peninsularensis within a polytomy alongside Mystriosaurus laurillardi and other Asian teleosaurids, supporting a monophyletic Teleosauroidea. In addition, the revision of Indosinosuchus kalasinensis as a junior synonym of I. potamosiamensis also strengthens the taxonomic framework of the genus Indosinosuchus. Indosinosuchus peninsularensis sp. nov., discovered in a low-energy lagoonal environment, offers significant insights on the ecological preferences of teleosaurids. In contrast to the fluvially deposited Phu Kradung Formation of northeastern Thailand, the lagoonal and marginal marine sediments of the Khlong Min Formation are considered indicative of a broad spectrum of habitat occupation by Asian teleosauroids. Based on these observations, a high degree of ecological plasticity has been inferred for Thai teleosaurids, and their extensive dispersal across both the Sibumasu and Indochina terranes during the Middle to Late Jurassic has been further substantiated. The recognition of I. peninsularensis sp. nov. contributes to our understanding of teleosaurid diversity and paleobiogeography in Southeast Asia.

Keywords: Indosinosuchus, Khlong Min Formation, Sibumasu, Phu Kradung Formation, Indochina

Indosinosuchus peninsularensis sp. nov. from the Khong Min Formation, Ban Nam Pun, southern Thailand. Photographs and interpretive drawings of Indosinosuchus peninsularensis sp. nov. from the Khong Min Formation, Ban Nam Pun, Nakhon Si Thammarat Province, southern Thailand.
PRC-205: anterior rostrum in dorsal view (A, B) and dorsal vertebrae in ventral view (C, D). PRC-206: osteoderms and dorsal vertebrae in dorsal view (E, F) and ventral view (G, H).

Abbreviations: dv, dorsal vertebrae; en, external nares; mx, maxilla; n, nasal; ost, osteoderm; pmx, premaxilla.

CROCODYLOMORPHA Hay, 1930

THALATTOSUCHIA Fraas, 1901

NEOTHALATTOSUCHIA Young et al., 2024a; Young et al., 2024b

TELEOSAUROIDEA Delfino & Dal Sasso, 2006

TELEOSAURIDAE Geoffroy Saint-Hilaire, 1831

Genus Indosinosuchus Martin et al., 2019

Indosinosuchus peninsularensis 

Holotype: PRC 205 and PRC 206, comprising an anterior portion of the rostrum, osteoderms, and dorsal vertebrae.

Type locality: Ban Nam Pun, Bang Khan District, Nakhon Si Thammarat Province, southern Thailand.

Stratigraphic occurrence: Lower part of the Khlong Min Formation, Thung Yai Group, late Middle Jurassic to early Late Jurassic.

Diagnosis. Indosinosuchus peninsularensis, PRC 205, is characterized by the following combination of characters (autapomorphies denoted with*): (1) four premaxillary alveoli; (2) moderately laterally expanded premaxilla with subequal length and width, producing a broad yet unflared outline; (3) margin of premaxillary-maxillary suture is concave between the 4th premaxillary –1st maxillary alveoli; (4) the external narial opening is subcircular or slightly ‘8-shaped’ in dorsal view; (5) absence of incisive foramen at medial contact of premaxillae*; (6) anterior tip of nasals reaching the level of the 18th maxillary alveolus*.

Locality, lithostratigraphy, and petrographic characteristics of the fossiliferous limestone within the Khlong Min Formation at Ban Nam Pun, southern Thailand.
(A) Tectonic subdivision map of Thailand (modified after Udchachon et al., 2022), illustrating the distribution of Jurassic sedimentary rock units (based on Meesook & Saengsrichan, 2011). The Khlong Min Formation, including the Ban Nam Pun locality, is situated within the Sibumasu Terrane, whereas the Phu Kradung Formation and its equivalents are located within the Indochina and Sukhothai Terranes. (B) Simplified geological map of the Krabi–Khlong Thom–Trang region (adapted from Thailand Department of Mineral Resources, 1999; Meesook & Saengsrichan, 2011), with the study site marked by a red star.
(C) Field photograph of the fossiliferous limestone outcrop intercalated with mudstone. The rock hammer (circled) is 30 cm in length for scale. (D–F) Close-up view of fossiliferous limestone rich in bivalves, (D) Modiolus sp. assemblage, (E) Actinostreon sp. (F) Protocardia sp. (G) MF1: Bioclast wackestone characterized by shell fragments, benthic foraminifera (f), and peloids (p). The yellow arrow indicates a bivalve shell with geopetal fabric: the lower portion infilled with micritic matrix and peloids, and the upper portion filled with sparry calcite cement. (H) MF2: Bioclast-peloidal packstone to grainstone, dominated by peloids (p) and benthic foraminifers (f) with minor ostracod shells (o).

 Komsorn Lauprasert, Apirut Nilpanapan, Jeremy E. Martin, Julien Claude, Kamonlak Wongko, Kantanat Trakunweerayut, Nuntida Dobutr, Sita Manitkoon, Supanut Bhuttarach and Thanit Nonsrirach. 2026. A new teleosaurid (Crocodylomorpha, Thalattosuchia) from the Sibumasu Terrane of Southeast Asia and A Taxonomic Reassessment of Indosinosuchus. PeerJ. 14:e20944. DOI: doi.org/10.7717/peerj.20944 [2026-03-20]

 facebook.com/Lauprasert/posts/10164083724222162

 

[Paleontology • 2024] Enalioetes schroederi • A New Genus of metriorhynchid crocodylomorph from the Lower Cretaceous of Germany

Enalioetes schroederi 

Sachs, Young, Hornung, Cowgill, Schwab & Brusatte, 2024

 

 DOI: 10.1080/14772019.2024.2359946  

 

Abstract

Here we describe a new genus and species of metriorhynchid crocodylomorph, Enalioetes schroederi gen. et sp. nov., from the lower Valanginian Stadthagen Formation (Lower Cretaceous) of north-western Germany. Enalioetes schroederi is the most complete and well-preserved Cretaceous metriorhynchid skull known to date, preserving most of the cranium and mandible, the atlas-axis complex and the first postaxial cervical vertebra. The specimen was previously attributed to the coeval enigmatic metriorhynchid Enaliosuchus (a nomen dubium) and, more recently, to Cricosaurus. Although the specific epithet schroederi has been used frequently in the literature, it has never been formally established. Herein, we demonstrate that the new taxon is distinct from all known metriorhynchids by a unique combination of characters including several autapomorphies such as: the lack of bulbous dorsolateral expansion in the posterior nasal cavity; mediolateral distance between the orbital canals being approximately 1.5 times the diameter of the orbital canals; lacrimal with dorsoventrally deep anterior process ventral to the preorbital fossa being equal to or greater than the depth of the jugal anterior process and the anterodorsal process of the lacrimal; and ascending processes at atlas intercentrum extending far dorsally to level of neural canal. Enalioetes schroederi contributes to the sparse global record of Cretaceous metriorhynchids and represents one of the stratigraphically youngest occurrences of the group. It can thus help to enhance our understanding of the metriorhynchid diversity during the Cretaceous Period. 

Keywords: Metriorhynchidae, Thalattosuchia, Cretaceous, taxonomy, Germany

 

  Enalioetes schroederi

Sven Sachs, Mark T. Young, Jahn J. Hornung, Thomas Cowgill, Julia A. Schwab and Stephen L. Brusatte. 2024. A New Genus of metriorhynchid crocodylomorph from the Lower Cretaceous of Germany. Journal of Systematic Palaeontology. 22(1);  2359946. DOI: doi.org/10.1080/14772019.2024.2359946  

[Paleontology • 2023] Evaluating Growth in Macrospondylus bollensis (Crocodylomorpha: Teleosauroidea) in the Toarcian Posidonia Shale, Germany

Macrospondylus bollensis  Jäger, 1828

in Johnson, Amson & Maxwell, 2023.

DOI: 10.1002/spp2.1529 

 twitter.com/Michela_Johnson

 www.naturkundemuseum-bw.de

Abstract

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.

Keywords: Teleosauroidea, Crocodylomorpha, evolutionary allometry, ontogenetic allometry, Macrospondylus bollensis, Posidonia Shale Formation

 

Michela M. Johnson, Eli Amson and Erin E. Maxwell. 2023. Evaluating Growth in Macrospondylus bollensis (Crocodylomorpha, Teleosauroidea) in the Toarcian Posidonia Shale, Germany. Papers in Palaeontology. DOI: 10.1002/spp2.1529

  twitter.com/Michela_Johnson/status/1712128784130879786

 www.naturkundemuseum-bw.de/en/press/detailansicht/studie-zum-groessenwachstum-von-meereskrokodilen-in-der-jurazeit

  phys.org/news/2023-10-size-growth-marine-crocodiles-jurassic.html

[Paleontology • 2023] Turnersuchus hingleyae • A New early Diverging thalattosuchian (Crocodylomorpha: Thalattosuchia) from the Early Jurassic (Pliensbachian) of Dorset, U.K. and Implications for the Origin and Evolution of the Group

Turnersuchus hingleyae

Wilberg, Godoy, Griffiths, Turner & Benson,  2023

DOI: 10.1080/02724634.2022.2161909 

 twitter.com/PedroLGodoy 

Illustration: Júlia d'Oliveira twitter.com/tupandactylus 

ABSTRACT

Among archosaurs, thalattosuchian crocodylomorphs experienced the most extensive adaptations to the marine realm. Despite significant attention, the phylogenetic position of the group remains uncertain. Thalattosuchians are either the sister-group to Crocodyliformes, basal mesoeucrocodylians, or nest among longirostrine neosuchians. The earliest definite thalattosuchians are Toarcian, and already possess many synapomorphies of the group. All phylogenetic hypotheses imply a ghost lineage extending at least to the Sinemurian, and a lack of older or more plesiomorphic forms may contribute to the uncertain phylogenetic placement of the group. Here we describe a new species, Turnersuchus hingleyae, gen. et sp. nov., from the early Pliensbachian Belemnite Marl Member of the Charmouth Mudstone Formation (Dorset, U.K.). The specimen includes partially articulated cranial, mandibular, axial, and appendicular elements. It can be attributed to Thalattosuchia based on the following features: distinct fossa on the posterolateral corner of the squamosal; broad ventrolateral process of the otoccipital covering the dorsal surface of the quadrate; large supratemporal fenestrae lacking a flattened skull table; broadly exposed prootic; orbital process of quadrate lacking bony attachment with the braincase. This specimen represents the earliest thalattosuchian currently known from diagnostic material. Phylogenetic analyses of two published datasets recover Turnersuchus as the earliest diverging thalattosuchian, and sister to Teleosauroidea + Metriorhynchoidea. Bayesian tip-dating analyses suggest a Rhaetian or Sinemurian divergence of Thalattosuchia from other crocodylomorphs, depending on topology, with confidence intervals spanning from the Norian to the Pliensbachian. The new specimen extends the fossil record of Thalattosuchia, but the time-scaling analyses demonstrate that a significant ghost lineage remains.

 Turnersuchus hingleyae, gen. et sp. nov.

 

Eric W. Wilberg, Pedro L. Godoy, Elizabeth F. Griffiths, Alan H. Turner and Roger B. J. 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. Journal of Vertebrate Paleontology.  e2161909. DOI: 10.1080/02724634.2022.2161909  

  twitter.com/PedroLGodoy/status/1616568227936538624

[Paleontology • 2019] The Mystery of Mystriosaurus: Redescribing the poorly known Early Jurassic Teleosauroid Thalattosuchians Mystriosaurus laurillardi and Steneosaurus brevior

Mystriosaurus laurillardi Kaup, 1834

in Sachs, Johnson, Young & Abel, 2019. 

 DOI:  10.4202/app.00557.2018

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.

 Key words: Thalattosuchia, Teleosauroidea, Mystriosaurus, Jurassic, Toarcian Posidonienschiefer Formation, Whitby Mudstone Formation, Germany, UK.

Fig. 2. Teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834 (NHMUK PV OR 14781, holotype of Steneosaurus brevior Blake, 1876, lower Toarcian of Whitby (Yorkshire, UK); skull in lateral, dorsal, and ventral views.

Teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834:
HLMD V946-948, holotype, lower Toarcian of Altdorf (southern Germany); skull in dorsal view.
NHMUK PV OR 14781, holotype of Steneosaurus brevior Blake, 1876, lower Toarcian of Whitby (Yorkshire, UK); skull in dorsal view.
Reconstruction of Mystriosaurus laurillardi Kaup, 1834 cranium and mandible in dorsal view.

Systematic palaeontology

Thalattosuchia Fraas, 1901

Teleosauroidea Geoffroy Saint-Hilaire, 1831

Genus Mystriosaurus Kaup, 1834

Type species: Mystriosaurus laurillardi Kaup, 1834,
Altdorf bei Nürnberg, lower Toarcian, Lower Jurassic.

Mystriosaurus laurillardi Kaup, 1834

1834 Mystriosaurus laurillardi gen. et sp. nov.; Kaup 1834: p. 28 [not figured].

1876 Steneosaurus brevior sp. nov.; Blake 1876: pl. 1:1, 2.

 Holotype: HLMD V946-948, an incomplete cranium and mandible.

Type locality: Altdorf bei Nürnberg, Nürnberger Land district, Bavaria, southern Germany. Type horizon: Posidonienschiefer Formation, Schwarzjura Group, probably Harpoceras serpentinum Sub-Mediterranean Ammonite Zone, lower Toarcian, Lower Jurassic (Page 2003; German Stratigraphic Commission 2016).

Emended diagnosis.— Teleosauroid crocodylomorph with the following unique combination of characters (proposed autapomorphic characters indicated by an asterisk): robust skull with well-developed and extensive ornamentation on the premaxillae, maxillae, nasals*, frontal, prefrontal, lacrimal, jugal*,postorbital and squamosal*; frontal ornamentation composed of small sub-circular to elongate pits that are closely spaced or that fuse and become a ridge-groove pattern; mesorostrine snout (preorbital length is approximately 66% of skull length), which is broad near the orbits but narrows and becomes slightly more slender anteriorly; slight constriction of the snout in front of the orbits; ...

Photograph of teleosauroid thalattosuchian specimen (UH 7), lower Toracian of Holzmaden (southwestern Germany), which was described by Mueller-Töwe (2006) as “Steneosaurus” brevior Blake, 1876, and which we herein refer to tentatively as ?Mystriosaurus sp.

Conclusions:

The presented combination of characters clearly demonstrates that Mystriosaurus is a distinct and valid genus. Recognition of this taxon, and its presence in England and Germany, furthers our understanding of European teleosauroid biodiversity during the Toarcian. From lower Toarcian deposits of England, Luxembourg, and Germany, a diverse array of teleosauroids have been recovered: the lateral-orbited and small-bodied longirostrine species Steneosaurus gracilirostris; the large-bodied longirostrine form Steneosaurus bollensis; the mesorostrine and robust toothed taxon Mystriosaurus laurillardi, and the heavily armoured and longirostrine Platysuchus multiscrobiculatus (Westphal 1962; Johnson et al. 2018; Young and Steel in press). Although these taxa are found in many of the same formations, their geographical distributions need to be re-examined based on our developing understanding of their comparative anatomies. Nevertheless, our re-description of Mystriosaurus further highlights that teleosauroids had already achieved ecological diversity through niche partitioning, and large body-size by the early Toarcian.

Sven Sachs, Michela M. Johnson, Mark T. Young, and Pascal Abel. 2019.  The Mystery of Mystriosaurus: Redescribing the poorly known Early Jurassic Teleosauroid Thalattosuchians Mystriosaurus laurillardi and Steneosaurus brevior. Acta Palaeontologica Polonica. 64(3); 565–579. DOI:  10.4202/app.00557.2018

fosil.cl/mystriosaurus-laurillardi

[Paleontology • 2018] Magyarosuchus fitosi • A New Large-bodied Thalattosuchian Crocodyliform from the Lower Jurassic (Toarcian) of Hungary, with Further Evidence of the Mosaic Acquisition of Marine Adaptations in Metriorhynchoidea

Magyarosuchus fitosi 

Ősi​, Young, Galácz & Rabi, 2018

 DOI: 10.7717/peerj.4668 

Abstract

Based on associated and three-dimensionally preserved cranial and postcranial remains, a new thalattosuchian crocodyliform, Magyarosuchus fitosi gen. et sp. nov. from the Lower Jurassic (Upper Toarcian) Kisgerecse Marl Formation, Gerecse Mountains, Hungary is described here. Phylogenetic analyses using three different datasets indicate that M. fitosi is the sister taxon of Pelagosaurus typus forming together the basal-most sub-clade of Metriorhynchoidea. With an estimated body length of 4.67–4.83 m M. fitosi is the largest known non-metriorhynchid metriorhynchoid. Besides expanding Early Jurassic thalattosuchian diversity, the new specimen is of great importance since, unlike most contemporaneous estuarine, lagoonal or coastal thalattosuchians, it comes from an ‘ammonitico rosso’ type pelagic deposit of the Mediterranean region of the Tethys. A distal caudal vertebra having an unusually elongate and dorsally projected neural spine implies the presence of at least a rudimentary hypocercal tail fin and a slight ventral displacement of the distal caudal vertebral column in this basal metriorhynchoid. The combination of retaining heavy dorsal and ventral armors and having a slight hypocercal tail is unique, further highlighting the mosaic manner of marine adaptations in Metriorhynchoidea.

Systematic Paleontology

CROCODYLOMORPHA Hay, 1930 (sensu Nesbitt, 2011)

THALATTOSUCHIA Fraas, 1901 (sensu Young & Andrade, 2009)

METRIORHYNCHOIDEA Fitzinger, 1843 (sensu Young & Andrade, 2009)

MAGYAROSUCHUS gen. nov.

Type species—Magyarosuchus fitosi gen. et sp. nov. (type by monotypy).

Etymology— ‘Hungarian crocodile.’ Magyaro referring to the Hungarian people, and suchus is the Latinized form of the Greek soukhos (σoῦχoς), meaning crocodile.

MAGYAROSUCHUS FITOSI, gen. et sp. nov.

Etymology—‘Fitos’s Hungarian crocodile.’ The name refers to Attila Fitos, discoverer of the specimen in thanks for his donation of the fossil to science.

Type locality—one of the northwestern quarries of the Nagy-Pisznice Hill, close to Békás-canyon, eastern Gerecse Mountains, northwestern Hungary.

Type horizon—Bed 13, Kisgerecse Marl Formation, Transdanubian Central Range. Grammoceras striatulum ammonite Subzone, G. thouarsense ammonite Zone, Upper Toarcian, Lower Jurassic (Galácz et al., 2010).

Diagnosis— Large-sized (estimated body length: in the range of 4.67–4.83 m) metriorhynchoid thalattosuchian with the following unique combination of characters (proposed autapomorphic characters are indicated by an asterisk (*)): tooth crown carinae development variable, being well-developed apically, beginning to develop mid-crown and absent in the basal region; enamel ornamentation is composed of ridges that differ in arrangement on the labial and lingual surfaces, being more widely spaced on the labial surface than the lingual surface, with the lingual surface having tightly packed apicobasal ridges basally which apically become shorter and discontinuous, and the apical lingual ridges on the mesial and distal margins bend towards the carinae (but do not contact them)*; abrupt change in centrum shape of the distal caudal vertebrae, with strong mediolateral compression (i.e. distal vertebrae are clearly heteromorphic); dorsal osteoderms have irregularly shaped pits (including circular, ellipsoid, bean-shaped, triangular and quadrangular shapes), with an extreme variation in size (from small to very large), with elongate pits present on the ventrolateral surface running from the keel to the lateral margin*; dorsal osteoderms have an anterolateral process that is ‘indistinct,’ no longer being distinctly ‘peg-like,’ as their lateral margin is contiguous with that of the osteoderm ventrolateral surface*.

Conclusion: 

Here, we describe a new crocodylomorph taxon, Magyarosuchus fitosi gen. et sp. nov., based on a new skeleton from the Gerecse mountains of Hungary. Despite being incomplete and lacking the cranium, we demonstrate that this late Lower Jurassic taxon shows remarkable similarities with the iconic Lower Jurassic genus Pelagosaurus. Magyarosuchus and Pelagosaurus are found to be sister taxa in all three phylogenetic analyses undertaken herein, although the two characters uniting this arrangement are not known from other basal metriorhynchoids (due to poor preservation of taxa such as Teleidosaurus, Eoneustes and Zoneait). Therefore, we cannot be certain that the sister relationship between Magyarosuchus and Pelagosaurus is natural, or due to incomplete information. Regardless, both are found to be basal metriorhynchoids, near the start of the radiation that yielded dolphin-like crocodyliforms. Interestingly, M. fitosi is the oldest known thalattosuchian discovered from an ‘ammonitico rosso’ type pelagic deposit (rather than the usual estuarine, lagoonal or coastal ecosystems Lower Jurassic thalattosuchians are discovered from). The pelagic depositional environment and neritic associated cephalopod fauna are both consistent with the inferred open-marine adaptation of M. fitosi, namely a mediolaterally compressed distal caudal vertebra with an unusually elongated and dorsally projected neural spine which suggests the presence of a distal tail structure that could have been a hypocercal fin, or a precursor to it. The unique combination of retaining heavy dorsal and ventral armor, while having a slight hypocercal tail, on the other hand, highlights the mosaic manner of marine adaptations in Metriorhynchoidea. Furthermore, it underscores how little is still known about the timing and tempo of metriorhynchoid pelagic adaptations and their early radiation.

Attila Ősi​, Mark T. Young, András Galácz and Márton Rabi. 2018. A New Large-bodied Thalattosuchian Crocodyliform from the Lower Jurassic (Toarcian) of Hungary, with Further Evidence of the Mosaic Acquisition of Marine Adaptations in Metriorhynchoidea.  PeerJ. 6:e4668. DOI: 10.7717/peerj.4668

 twitter.com/mty_84/status/994484304561557506

22 év után derült ki, hogy új faj a gerecsei őskrokodil  hir.press/tech-tudomany/22-ev-utan-derult-ki-hogy-uj-faj-a-gerecsei-oskrokodil/

[Paleontology • 2017] Lemmysuchus obtusidens • Re-description of ''‘Steneosaurus’ obtusidens'' Andrews, 1909, An Unusual Macrophagous Teleosaurid Crocodylomorph from the Middle Jurassic of England

Lemmysuchus ‘Steneosaurus’ obtusidens'' Andrews, 1909

DOI: 10.1093/zoolinnean/zlx035  

Abstract

Teleosaurids were a clade of crocodylomorphs that attained near-global distribution during the Jurassic Period. Within Teleosauridae, one particular sub-clade of durophagous/macrophagous taxa achieved large body sizes and were apex predators in shallow marine environments during the Late Jurassic and Early Cretaceous in Europe and around the coast of the Tethys Seaway. Unfortunately, the origins of this clade are still poorly understood. ‘Steneosaurus’ obtusidens is a little-studied macrophagous species from the Oxford Clay Formation (Callovian, Middle Jurassic) of the UK and near Migné-les-Lourdines (Middle Callovian) in France. Despite being considered a sister taxon of the Late Jurassic taxon Machimosaurus, the taxonomy of ‘S.’ obtusidens remains unclear. Although three different synonymies have been proposed (variously a subjective synonym of other taxa), these taxonomic hypotheses have not been based on detailed anatomical comparisons and thus have not been tested. Here, we re-describe the holotype of ‘S.’ obtusidens, demonstrate that it is indeed a valid taxon, restrict the referred specimens to a fragmentary skeleton, nearly complete skull, and partial rostrum, and establish a new monotypic genus, Lemmysuchus. Our re-description reveals five autapomorphies for Lemmysuchus obtusidens and nine apomorphic characters that support the tribe Machimosaurini (Lemmysuchus + Machimosaurus).

Keywords: Crocodylomorpha, Lemmysuchus, Machimosaurus, Steneosaurus, Teleosauridae, Thalattosuchia

Michela M. Johnson, Mark T. Young, Lorna Steel, Davide Foffa, Adam S. Smith, Stéphane Hua, Philipe Havlik, Eliza A. Howlett and Gareth Dyke. 2017. Re-description of ''‘Steneosaurus’ obtusidens'' Andrews, 1909, An Unusual Macrophagous Teleosaurid Crocodylomorph from the Middle Jurassic of England. Zoological Journal of the Linnean Society. in press.  DOI: 10.1093/zoolinnean/zlx035 

Late Motorhead singer 'Lemmy' has extinct crocodile named after him  japantimes.co.jp/news/2017/08/09/world/science-health-world/late-motorhead-singer-lemmy-extinct-crocodile-named

[Paleontology • 2016] Machimosaurus rex • The Largest Thalattosuchian (Crocodylomorpha) supports Teleosaurid Survival Across the Jurassic-Cretaceous Boundary

Machimosaurus rex Fanti, Miyashita, Cantelli, Mnasri, Dridi, Contessi & Cau, 2016

Life reconstruction: Davide Bonadonna theropoda.blogspot.com
 DOI: 10.1016/j.cretres.2015.11.011 

Fig. 8. Comparison among skulls of Machimosaurus.
 (A) holotype of M. buffetauti, (B) neotype of M. mosae, (C) estimated size of the ‘Leira specimen’ of M. hugii,
 (D) holotype of Machimosaurus rex. Dashed areas in (A) and (B) indicate size of largest known individuals of those species.
(E) Reconstruction of Machimosaurus rex body based on preserved elements.

Figures (A)–(C) modified from Young et al. (2014b).  DOI: 10.1016/j.cretres.2015.11.011  

Highlights

• Machimosaurus rex is a new teleosaurid crocodylomorph from Tunisia.

• It is the largest known thalattosuchian, up to 10 m in length.

• M. rex, the first Cretaceous teleosauroid found, was the last-surviving of its group.

Abstract

A new teleosaurid from the Lower Cretaceous of Tataouine (Tunisia), Machimosaurus rex sp. nov., definitively falsifies that these crocodylomorphs faced extinction at the end of the Jurassic. Phylogenetic analysis supports its placement closer to M. hugii and M. mosae than M. buffetauti. With the skull length up to 160 cm and an estimated body length of 10 m, M. rex results the largest known thalattosuchian, and the largest known crocodylomorph at its time. This giant thallatosuchian probably was an ambush predator in the lagoonal environments that characterized the Tethyan margin of Africa during the earliest Cretaceous. Whether the Jurassic-Cretaceous mass extinction was real or artefact is debated. The discovery of M. rex supports that the end-Jurassic crisis affected primarily Laurasian biota and its purported magnitude is most likely biased by the incomplete Gondwanan fossil record. The faunal turnovers during the J-K transition are likely interpreted as local extinction events, triggered by regional ecological factors, and survival of widely-distributed and eurytypic forms by means of habitat tracking.

Keywords: Lower Cretaceous; Machimosaurus; Teleosauridae; Thalattosuchia; Tunisia

Systematic paleontology

Crocodylomorpha Hay, 1930

Thalattosuchia Fraas, 1901

Teleosauridae Saint-Hilaire, 1831

Machimosaurus von Meyer, 1837

Machimosaurus rex sp. nov.

(ZooBank code: LSID urn:lsid:zoobank.org:act:1A11E9B9-0B1C-4557-92B7-165168658C17)

Etymology. The species name rex, Latin for “king”, refers to its majestic size among known Machimosaurus and all thalattosuchians.

Holotype. ONM NG NG 1–25, 80, 81, and 83–87

( Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 and Fig. 7D; Table 1).

Fig. 4. Machimosaurus rex type skull,
(A) in situ photograph showing dorsally exposed preserved bones, (B) prepared ventral surface.

Abbreviations: fr, frontal; lj, left jugal; la, lacrimal; ld, left dentary; lmx, left maxilla; lna, left nasal; lpd, left postdentary elements; lposq, left postorbitalsquamosal bar; os, osteoderm; pa, palatal element; rd, right dentary; rmx, right maxilla; rna, right nasal; rpd, right postdentary elements; rposq, right postorbital-squamosal bar; stfo, floor of supratemporal fossa; tp, turtle plastron element. Scale bar = 50 cm.

  DOI: 10.1016/j.cretres.2015.11.011 

Locality and horizon. Touil el Mhahir, Tataouine Governorate, Tunisia; Douiret Sand Member, Douiret Formation, Hauterivian, Lower Cretaceous.

Fig. 1. (A) Geographic location and type locality of Machimosaurus rex. (B) Simplified geological map of the Tataouine basin of southern Tunisia showing the Touil el Mhahir locality.

DOI: 10.1016/j.cretres.2015.11.011 

Diagnosis. Teleosaurid differing from other species by unique combination of: adult basicranial length >155 cm ( Fig. 5); rostrum ornamented by densely arranged, parallel longitudinal ridges; orbit elliptical; interorbital space narrow (one fifth length of skull posterior to orbit); anteromedial margin of supratemporal fossae round; frontal not extended anteriorly to orbit and with reduced orbital margin; relatively large maxillary alveoli; anterior dorsal neural spine height less than centrum height; dorsal osteoderms with tightly packed pits that are round centrally and ellipsoid peripherally.

Fig. 8. Comparison among skulls of Machimosaurus
(A) holotype of M. buffetauti, (B) neotype of M. mosae, (C) estimated size of the ‘Leira specimen’ of M. hugii, (D) holotype of Machimosaurus rex. Dashed areas in (A) and (B) indicate size of largest known individuals of those species. (E) Reconstruction of Machimosaurus rex body based on preserved elements.

Figures (A)–(C) modified from Young et al. (2014b).  DOI: 10.1016/j.cretres.2015.11.011 

Machimosaurus rex Fanti, Miyashita, Cantelli, Mnasri, Dridi, Contessi & Cau, 2016

Artwork by Davide Bonadonna theropoda.blogspot.com
DOI: 10.1016/j.cretres.2015.11.011

Conclusion: 

Machimosaurus rex sp. nov. is based on the articulated skeleton of a giant crocodylomorph from the Hauterivian of Tunisia. This taxon represents the first indisputable Cretaceous teleosauroid, and the first member of this clade from Africa based on well preserved remains. With a basicranial length approaching 160 cm (and a partial skeleton indicating a total body length around 10 m), M. rex is the largest known thalattosuchian. Both paleoecological data and morphological features suggest that this species was an ambush generalist predator with an ecology comparable to extant semi-aquatic crocodilians. The discovery of M. rex falsifies a global mass extinction event at the J-K transition (i.e., teleosauroid extinction), thereby highlighting the problem of sampling bias in the reconstruction of large-scale patterns in the geological record. The new Tunisian teleosaurid points to a conservative interpretation of faunal turnovers during the J-K transition: local extinction events triggered by regional ecological factors and survival of widely-distributed and eurytypic forms by means of habitat tracking.

Federico Fanti, Tetsuto Miyashita, Luigi Cantelli, Fawsi Mnasri, Jihed Dridi, Michela Contessi and Andrea Cau. 2016. The Largest Thalattosuchian (Crocodylomorpha) supports Teleosaurid Survival Across the Jurassic-Cretaceous Boundary. Cretaceous Research. In Press. DOI: 10.1016/j.cretres.2015.11.011 

http://theropoda.blogspot.com/2016/01/il-re-dei-sauri-battaglieri-morfologia.html

[Paleontology • 2010] The evolution of Metriorhynchoidea (Mesoeucrocodylia, Thalattosuchia): an integrated approach using geometric morphometrics, analysis of disparity, and biomechanics; with Eoneustes Gen. nov. & Gracilineustes Gen. nov.

Skull and limb of Gracilineustes leedsi (formerly Metriorhynchus laeve).

http://archive.org/stream/descriptivecatal02brit#page/n281/mode/2up

Abstract

Metriorhynchoid crocodylians represent the pinnacle of marine specialization within Archosauria. Not only were they a major component of the Middle Jurassic–Early Cretaceous marine ecosystems, but they provide further examples that extinct crocodilians did not all resemble their modern extant relatives. Here, we use a varied toolkit of techniques, including phylogenetic reconstruction, geometric morphometrics, diversity counts, discrete character disparity analysis, and biomechanical finite-element analysis (FEA), to examine the macroevolutionary history of this clade. All analyses demonstrate that this clade became more divergent, in terms of biodiversity, form, and function, up until the Jurassic–Cretaceous boundary, after which there is no evidence for recovery or further radiations. A clear evolutionary trend towards hypercarnivory in Dakosaurus is supported by phylogenetic character optimization, morphometrics, and FEA, which also support specialized piscivory within Rhacheosaurus and Cricosaurus. Within Metriorhynchoidea, there is a consistent trend towards increasing marine specialization, with the hypermarine Cricosaurus exhibiting numerous convergences with other Mesozoic marine reptiles (e.g. loss of the deltopectoral crest and retracted external nares). In addition, biomechanics, morphometrics, and character-disparity analyses consistently distinguish the two newly erected metriorhynchid subfamilies. This study illustrates that together with phylogeny, quantitative assessment of diversity, form, and function help elucidate the macroevolutionary pattern of fossil clades.

Keywords: Crocodylia; diversity; ecomorphology; functional morphology; phylogeny

M. T. Young, S. L. Brusatte, M. Ruta and M. B. Andrade. 2010. The evolution of Metriorhynchoidea (Mesoeucrocodylia, Thalattosuchia): an integrated approach using geometric morphometrics, analysis of disparity, and biomechanics. Zoological Journal of the Linnean Society. 158(4):801-859

DOI: 10.1111/j.1096-3642.2009.00571.x