[Paleontology • 2026] Gondwananectes osvaldoi • A new Middle Jurassic marine reptile from Gondwana clarifies the origin of Cryptoclidia, the most successful group of plesiosaurs

Gondwananectes osvaldoi

Otero, Acuña, Vargas, Rojas, Ortiz & Aguirrezabala, 2026

DOI: doi.org/10.1002/spp2.70068 

 x.com/ThePalAss

Abstract 

Cryptoclidia (Plesiosauria, Plesiosauroidea) was a major clade of marine reptiles that originated during the Jurassic. The early evolution of Cryptoclidia is documented by records of Cryptoclididae from the Middle Jurassic (174.7–165.1 Ma) and onwards in Europe, the Caribbean and South America. However, the origin of Cryptoclidia itself has remained obscure. Only some traits shared with Cryptoclidia are found in the Toarcian (184.2–174.7 Ma) taxa Plesiopterys wildi and Franconiasaurus brevispinus, from southern Europe. Here we describe a small-bodied sub-adult skeleton belonging to a new plesiosaurian taxon from the Middle Jurassic (c. 170 Ma) of the Atacama Desert (former southwestern Gondwana). The new taxon has single-headed ribs in its axial skeleton, and its combination of novel and ancestral features place it as the sister taxon of Cryptoclidia. The lower Bajocian stage, the phylogenetic position of the new taxon, as well as its palaeogeographic occurrence, point to an older origin and dispersal of Cryptoclidia ancestors, reinforcing the notion that an early Caribbean corridor between the Pacific and Tethyan realms was already functional during the Middle Jurassic.

Keywords: marine reptile, plesiosaurian, phylogeny, Middle Jurassic, Gondwana, palaeogeography

Gondwananectes osvaldoi

 

Rodrigo A. Otero, Sergio Soto Acuña, Alexander O. Vargas, Jennyfer Rojas, Héctor Ortiz, Guillermo Aguirrezabala. 2026. A new Middle Jurassic marine reptile from Gondwana clarifies the origin of Cryptoclidia, the most successful group of plesiosaurs. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.70068 [08 March 2026] 

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[Paleontology • 2025] Lijiangosaurus yongshengensis • Earliest Long-necked sauropterygian (Sauropterygia: Nothosauria) and Plasticity of Vertebral Evolution in Sauropterygian marine reptiles

 

Lijiangosaurus yongshengensis

W. Wang, Shang, J. Wang, Zi & Li, 2025

 

DOI: doi.org/10.1038/s42003-025-08911-1

Artwork by Kelai LI

Abstract

A long neck is a morphological innovation in vertebrates, particularly iconic in many plesiosaurs, while the function of these long necks in plesiosaurs remains controversial. Here, we report Lijiangosaurus yongshengensis gen. et sp. nov. from a previously unknown early Middle Triassic locality in southwestern China. This taxon represents the earliest known sauropterygian evolving an exceptionally long neck with 42 cervical vertebrae, and is identified as a nothosaur rather than the immediate ancestors of plesiosaurs. Our discovery demonstrates that extreme cervical elongation developing more than 30 cervical vertebrae emerged in sauropterygians prior to the rise of plesiosaurs and their pistosaur ancestors. Furthermore, Lijiangosaurus possesses a unique type of accessory intervertebral articulation compared with other reptiles, and we attribute this structure to reducing body undulation. This discovery increases the known diversity of accessory intervertebral articulations in reptiles, and underscores the high plasticity of the vertebral column in the early evolution of sauropterygians.

Type specimen (YSBB208) of Lijiangosaurus yongshengensis nov. gen. et sp. 
 Image of the skeleton on a large block of limestone (a); interpreted illustration of the skeleton with different osteological parts labeled and marked in multiple colors (b); cv is the abbreviation of cervical vertebra; reconstruction of the complete skeleton in strict accordance with the preserved morphology in corresponding colors (c); scale bars equal 10 cm.

Systematic paleontology

Reptilia Linnaeus, 1758

Diapsida Osborn, 1903

Sauropterygia Owen, 1860

Nothosauria Baur, 1889

Emended definition: Referred to the phylogenetic hypotheses recovered in this paper, the maximum clade definition of Nothosauria is reformulated as follows: all taxa more closely related to Brevicaudosaurus jiyangshanensis, Germanosaurus schafferi, and Nothosaurus species than Keichousaurus hui, Simosaurus gaillardoti, or Corosaurus alcovensis.

Composition: Based on the phylogenetic hypotheses in this study, Nothosauria includes Brevicaudosaurus jiyangshanensis, Germanosaurus schafferi, Lijiangosaurus yongshengensis, Wangosaurus brevirostris, and all the species of Nothosaurus and Lariosaurus.

Diagnosis: Nothosauria is a clade distinguished from other eosauropterygians by a combination of the following characters: dorsal exposure of prefrontal reduced, pineal foramen displaced posteriorly, mandibular articulation approximately at the level of the occipital condyle, diastema between premaxillary and maxillary teeth present, and four or more sacral ribs.

Lijiangosaurus yongshengensis gen. et sp. nov

 

Etymology: Both the generic and species names refer to the fossil site of Yongsheng County, Lijiang City, Yunnan Province, China. This currently only known specimen of this genus and species is the first Mesozoic reptile collected from this area.

Diagnosis: A medium-to-large-sized nothosaurian distinguished from other nothosaurians by a proportionally small skull with body length over 2.5 m (smaller than a few species of Nothosaurus like N. giganteus and N. mirabilis, but larger than most nothosaurian taxa), a remarkably high count of 42 cervical vertebrae, a dorsal neural spine comparable to the corresponding centrum in height (distinctly shorter than N. mirabilis, but longer than all other nothosaurians), entepicondylar foramina lost, accessory intervertebral articulation of infraprezygapophysis and infrapostzygapophysis present in dorsal and anterior caudal vertebrae. It can be further distinguished from non-nothosaurian eosauropterygians (especially pistosauroids) by the absence of interpterygoid vacuity, a ventral flange along the ventromedial edge of the quadrate ramus of the pterygoid, well-developed and extending further posteriorly up to the quadrate, an obturator foramen opening in the adult, and other synapomorphies of nothosaurians.

Phylogenetic relationship of Lijiangosaurus yongshengensis nov. gen. et sp. with other sauropterygians.
The topology is based on a strict consensus tree from the 16 most parsimonious trees using an updated morphological character dataset from [Wang, et al. 2022]. Lijiangosaurus yongshengensis is the sister group of Wangosaurus brevirostris, both belonging to Nothosauria but not Plesiosauria.

Reconstruction of nothosaurs about 240 million years ago revealing a hidden diversity from southwestern China.
Taxa include Lijiangosaurus yongshengensis (central), Nothosaurus yangjuanensis (upper left), Nothosaurus luopingensis (upper right), Brevicaudosaurus jiyangshanensis (lower left), and Lariosaurus hongguoensis (lower right). All these nothosaurian taxa lived in the Middle Triassic in Yunnan and Guizhou provinces (Artwork by Kelai Li).

 Wei Wang, Qinghua Shang, Jiansheng Wang, Hongke Zi and Chun Li. 2025. Earliest Long-necked sauropterygian Lijiangosaurus yongshengensis and Plasticity of Vertebral Evolution in Sauropterygian marine reptiles. Communications Biology. 8, 1551. DOI: doi.org/10.1038/s42003-025-08911-1 [1 November 2025]

  

[Paleontology • 2025] The Osteology, Taxonomy, and Phylogenetic Placement of Seeleyosaurus guilelmiimperatoris (Plesiosauroidea: Microcleididae) from the Lower Jurassic Posidonia Shale of Germany

 

Seeleyosaurus guilelmiimperatoris (Dames, 1895) 

Sachs, Madzia, Marx, Roberts, Hampe et Kear, 2025. 

 DOI: doi.org/10.1002/ar.25620 

Researchgate.net/publication/389208223

Abstract

Seeleyosaurus guilelmiimperatoris is an early-diverging plesiosauroid from the lower Toarcian (Lower Jurassic) of the Posidonienschiefer Formation (Posidonia Shale) of Holzmaden, southwestern Germany. It is known from almost complete skeletons of two osteologically mature individuals, the holotype and a referred specimen that was largely destroyed during World War II. Although well-preserved and substantially complete, the anatomy of Seeleyosaurus and its taxonomic and phylogenetic significance remain insufficiently understood. Here, we provide a complete osteological description of the taxon. Seeleyosaurus guilelmiimperatoris can be diagnosed based on a unique combination of characters, including one autapomorphy: the tall and basally constricted neural spines of the posterior cervical, pectoral, and dorsal vertebrae which have a sinusoidal shape in lateral view. Our study supports the validity of the plesiosauroid taxon Plesiopterys wildi, which was considered a junior synonym of Seeleyosaurus in a previous joint assessment of the taxa. Our phylogenetic evaluation places S. guilelmiimperatoris among Microcleididae, in congruence with previous studies. However, in contrast to earlier phylogenetic reconstructions, our analyses, which take into account numerous changes to the character matrix, reconstruct S. guilelmiimperatoris as falling within the Microcleidus clade. While we admit that Seeleyosaurus might potentially be considered a species of Microcleidus, we refrain from promoting this nomenclatural change pending an osteological and taxonomic reassessment of Microcleidus spp. as well as other, potentially closely related forms, such as Lusonectes sauvagei.

Keywords: Plesiosauria, Microcleididae, Seeleyosaurus, Toarcian, Lower Jurassic, Germany

Skeleton of the referred specimen of Seeleyosaurus guilelmiimperatoris (SMNS 12039). (a) initial slab mount with original skull and unaltered paddles (from Fraas, 1910a, plate 6). (b) cast of the modified skeleton with modeled skull and arranged paddles (SMNS collection). Scale equals 50 cm.

Seeleyosaurus (left) and Thaumatosaurus, now Meyerasaurus (right)

as depicted in Water reptiles of the past and present (1914)

Sven Sachs, Daniel Madzia, Miguel Marx, Aubrey J. Roberts, Oliver Hampe and Benjamin P. Kear. 2025. The Osteology, Taxonomy, and Phylogenetic Placement of Seeleyosaurus guilelmiimperatoris (Plesiosauroidea, Microcleididae) from the Lower Jurassic Posidonia Shale of Germany. The Anatomical Record. DOI: doi.org/10.1002/ar.25620 [21 February 2025]

 Researchgate.net/publication/389208223_The_osteology_taxonomy_and_phylogenetic_placement_of_Seeleyosaurus_from_the_Lower_Jurassic_Posidonia_Shale_of_Germany

[Paleontology • 2025] Plesionectes longicollum • An unusual early-diverging plesiosauroid from the Lower Jurassic Posidonia Shale of Holzmaden, Germany

Plesionectes longicollum 

Sachs​ & Madzia, 2025 

DOI: doi.org/10.7717/peerj.19665 

life reconstruction by Peter Nickolaus.

 facebook.com/DanielMadzia

Abstract 

The lower Toarcian Posidonia Shale at Holzmaden, Southwest Germany, has yielded some of the most remarkable Lower Jurassic marine tetrapod specimens, including five plesiosaur taxa identified from nearly complete skeletons. This study provides a comprehensive description of an osteologically immature plesiosauroid skeleton found in a Holzmaden quarry in 1978. Despite that the specimen has been researched in the past, previous studies have been either brief or targeted some specific aspects of the specimen, such as its soft tissue preservation. The anatomy and taxonomy of the specimen have never been explored in detail. We reinterpret several of its osteological features and evaluate their taxonomic and phylogenetic significance. Our findings reveal that the specimen possesses an unusual combination of character states, which are not markedly affected by ontogenetic development, warranting the designation of a new taxon, Plesionectes longicollum gen. et sp. nov., thereby increasing the known plesiosaur diversity of both the Toarcian age and the Posidonia Shale.

Skeleton of Plesionectes longicollum gen. et sp. nov. (SMNS 51945).

Scale bar equals 30 cm.

Plesiosauria De Blainville, 1835

Plesiosauroidea Gray, 1825

Plesionectes gen. nov.

 

Etymology. The name Plesionectes derives from plēsíon (Greek), meaning “close”, “near”, referring to its plesiosaur affinities, and nēktēs (Greek), “swimmer”, common suffix in plesiosaur taxon names.

Plesionectes longicollum sp. nov.

Type locality and horizon. Holzmaden, Esslingen District, Baden-Württemberg, southwestern Germany; lower Toarcian (Lias ɛII1, ‘Koblenzer’, Dactylioceras tenuicostatum Zone, D. semicelatum Subzone; Hauff, 1921; Riegraf, Werner & Lörcher, 1984; Maisch, 2021), Lower Jurassic.

Diagnosis. Plesiosauroid plesiosaur bearing following unique combination of characters states: paraoccipital process being considerably longer as the height of the exoccipital body; neck comprising ≥43 cervical vertebrae; V-shaped neurocentral suture in the cervical and pectoral vertebrae (potential local autapomorphy sensu Beeston et al., 2024); conjoined parapophysis and diapophysis in the anterior, middle, and the majority of the posterior cervicals, one rib facet formed in the posteriormost cervical vertebrae; cervical rib processes strap-shaped and pronounced in anterior and mid-neck region; posterior cervical and pectoral neural spines not considerably taller than long (mostly < 1:2), lacking constriction at base; dorsal vertebral series comprising 20–21 vertebrae.

Etymology. The name longicollum derives from longus (Latin), meaning “long”, and collum (Latin), “neck”, in reference to its long neck, comprising at least 43 vertebrae.

Plesionectes longicollum 

life reconstruction by Peter Nickolaus.

Sven Sachs​ and Daniel Madzia. 2025. An unusual early-diverging plesiosauroid from the Lower Jurassic Posidonia Shale of Holzmaden, Germany. PeerJ. 13:e19665. DOI: doi.org/10.7717/peerj.19665 

 facebook.com/DanielMadzia/posts/10239111282586232

[Paleontology • 2025] Traskasaura sandrae • A Name for the Provincial Fossil of British Columbia: A Strange New elasmosaur Taxon from the Santonian of Vancouver Island

 

Traskasaura sandrae

O’Keefe, Smith, Clark, Otero, Perella & Trask, 2025

DOI: doi.org/10.1080/14772019.2025.2489938 

Abstract

The first elasmosaurid skeleton from the Haslam Formation (Upper Santonian) of the Nanaimo Group (Late Cretaceous) on Vancouver Island was first described in 2002, and has recently been declared the Provincial Fossil of British Columbia. Since then, additional fossils have been recovered: an isolated right humerus and a well-preserved, osteologically immature skeleton comprising thorax, girdles and limbs. The Haslam material can now support further taxonomic assessment, and we erect the species Traskasaura sandrae based on it. Traskasaura possesses a strange mosaic of features. The mandible is plesiomorphic as seen in Libonectes: relatively narrow with large teeth and a broad symphysis. The skull therefore lacks any of the radical oral cavity adaptations seen in basal aristonectines. The neck of the Haslam animal is also plesiomorphic, with at least 36 preserved cervical vertebrae having vertebral length indices (VLIs) over 100 (the total number of cervicals is not known). The centra lack the anteroposterior compression and midline longitudinal constriction characteristic of derived aristonectines, yet the cervical ribs trend forward – a condition known only in derived aristonectines and Vegasaurus. The autapomorphic coracoid of Traskasaura differs greatly from any known elasmosaurid; the cardiform recess is reduced and posteriorly located, with some similarities to that of Aristonectes quiriquinensis. The humerus is autapomorphic, possessing a relatively straight shaft, pronounced ventral camber and an articular facet on the leading edge that makes a 90° angle with the radial facet. Taken together, these features document a new genus, with a plesiomorphic axial skeleton, but with several convergent appendicular adaptations with derived aristonectines. A revised phylogenetic analysis of Elasmosauridae recovered the new taxon in a basal position. Therefore, the postcranial adaptations shared with derived aristonectines appear to be convergent.

Keywords: elasmosaur, Haslam Formation, plesiosaur, Santonian

Sauropterygia Owen, Citation1860

Order Plesiosauria de Blainville, Citation1835

Family Elasmosauridae Cope, Citation1869

Traskasaura sandrae gen. et sp. nov.

Etymology: The genus is named in honour of Michael and Heather Trask, who discovered the holotype specimen along the banks of the Puntledge river in 1988, and the Greek word saûros, lizard; the Latin conjugation is feminine. The species name sandrae honours Sandra Lee O’Keefe (née Markey), Pacific Northwest native and, like Elizabeth Nicholls, a valiant warrior in the fight against breast cancer. In loving memory.

F. Robin O’Keefe, Elliott Armour Smith, Robert O. Clark, Rodrigo A. Otero, Anna Perella and Patrick Trask. 2025. A Name for the Provincial Fossil of British Columbia: A Strange New elasmosaur Taxon from the Santonian of Vancouver Island. Journal of Systematic Palaeontology. 23(1); 2489938. DOI: doi.org/10.1080/14772019.2025.2489938 [22 May 2025] 

[Paleontology • 2025] Novel Record of Placodont Remains including A Henodus Cranium from the Upper Triassic Silves Group of the Algarve, southern Portugal

 

in Ruciński, Campos, Mateus et Werneburg, 2025. 

DOI: doi.org/10.1080/02724634.2025.2460445 

ABSTRACT

Recent fieldwork in the Upper Triassic deposits of the Silves Group in the Algarve, southern Portugal revealed novel cyamodontid placodont material. The collection includes a partial skull and numerous isolated armor plates from four localities in Silves and Loulé municipalities. The skull shows a strong affinity to henodontid placodonts, especially to Henodus chelyops from Tübingen-Lustnau in Germany. It shares features such as a rectangular outline of the cranium, occurrence of a broad spatulate rostrum, and toothless maxillae with curved longitudinally extending grooves. The only unambiguous difference observed pertains to the more robust and convex snout shape of the new specimen. Based on these multiple similarities, the specimen is identified as Henodus sp., but poor preservation prevents species-level identification. The new specimen from Portugal represents the second record of Henodus and illustrates a wider geographic distribution of that genus, extending beyond the Germanic Basin and reaching coastal areas near the westernmost branch of the Neotethys. The age of the deposits where the cranium was found is not well-established but refers to a time interval within the upper Carnian–Rhaetian, suggesting the specimen may be younger than other henodontid records. The novel Henodus material found in the continental, but likely the near-coastal depositional setting, concurs with the known records of brackish to the freshwater habitat of the other henodontid placodonts. The occurrence of abundant armor plates assigned to Cyamodontidae at multiple sites and stratigraphic horizons indicates that placodonts were common in the south Iberian margin.

Paleogeographic context of recorded Henodontidae remains.
A, paleogeographic map of the world during the Late Triassic (Colorado Plateau Geosystems Inc., license nr. #110719).
B, magnification of the map of the Late Triassic world illustrating the area of the western Neotethys. Approximate locations of Henodontidae-bearing sites are indicated by a star. Drawing of Henodus chelyops after Rieppel et al. (2000). Drawing of Parahenodus atacensis after de Miguel Chaves et al. (2018). Photos of the Portuguese specimen ML. A9182 is referred to as Henodus sp. with shape contour and established bone extensions (compare with Figs 4, 5). Scale bars represent 20 mm.

 Abbreviations: AB, Algarve Basin; AV, Avalonia; BM, Bohemian Massif; CEB, Central European Basin (which includes Germanic Basin); EEP, East European Platform; IB, Iberian Basin; IM, Iberian Massif; MG, Maghrabian-Gibraltar rift; SP, Sahara Platform.

 Summary of the placodont material from Upper Triassic of the Algarve.
A, reconstruction of Henodus by Jakub Kowalski and Piotr Janecki.
B, transversely expanded armor plate from Algarve, interpreted to possibly stem from the medial portion of Henodus carapace. C, equilateral armor plate from the Algarve interpreted to possibly stem from the marginal portion of Henodus carapace. D, photogrammetry-based image of Henodus cranium (ML. A9182).

Maciej Ruciński, Hugo Campos, Octávio Mateus and Ingmar Werneburg. 2025. Novel Record of Placodont Remains including A Henodus Cranium from the Upper Triassic Silves Group of the Algarve, southern Portugal. Journal of Vertebrate Paleontology. e2460445. DOI: doi.org/10.1080/02724634.2025.2460445 

[Paleontology • 2024] Dianmeisaurus mutaensis • A New pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of southwestern China and its phylogenetic and biogeographic implications

Dianmeisaurus mutaensis 

Hu, Li & Liu, 2024

DOI: 10.1186/s13358-023-00292-4

Abstract

After the devastating Permo-Triassic Mass Extinction, several new groups of large reptilian predators invaded the sea in the early part of the Triassic. Among these predators, sauropterygians, consisting of placodonts, pachypleurosaurs, nothosaurs and pistosaurs (including the iconic plesiosaurs), displayed the greatest diversity at both the generic and species levels, and persisted from the Early Triassic to the Late Cretaceous. Here, we report a new species of Pachypleurosauria, Dianmeisaurus mutaensis sp. nov., from a recently discovered Lagerstätte in the Upper Member of the Anisian Guanling Formation. The only known specimen of the new species was collected from a quarry near Muta village, Luxi County, Yunnan Province, South China. Our new phylogenetic analysis based on a novel data matrix recovered the new taxon as a sister group to Dianmeisaurus gracilis—a small pachypleurosaur from the Middle Triassic Luoping biota. The new phylogenetic analysis also collapsed the monophyly of the traditionally recognized Eusauropterygia. Pistosauroidea, Majiashanosaurus, and Hanosaurus comprise the consecutive sister groups to a new clade including Pachypleurosauria and Nothosauroidea. A monophyletic Pachypleurosauria, within which the clade consisting of Dianmeisaurus and Panzhousaurus occupies the basal-most position, is recovered by this study. The clade consisting of Dawazisaurus and Dianopachysaurus forms the sister group to the remaining pachypleurosaurs included in this study. Since Dianmeisaurus, Panzhousaurus, Dawazisaurus, and Dianopachysaurus are all exclusively known from South China, our study provides further evidence to the hypothesis that pachypleurosaurs had a palaeobiogeographic origin in the eastern Tethys.

Keywords: Marine reptiles, Pachypleurosauria, Dianmeisaurus, Phylogeny, Palaeobiogeographic origin

Systematic palaeontology

Sauropterygia Owen, 1860

Eosauropterygia Rieppel, 1994

Pachypleurosauria Nopcsa, 1928

Dianmeisaurus Shang & Li, 2015

The holotype of Dianmeisaurus mutaensis sp. nov. (HFUT MT-21-08-001).
A the skeleton in dorsal view; B the counterpart of A (natural mold). Scale bars equal 1 cm

The skull of Dianmeisaurus mutaensis sp. nov. (HFUT MT-21-08-001). A photo; B, interpreted drawing.

an, angular; ar, articular; ata, atlas arch; atc, atlas centrum; axc, axial centrum; bo, basioccipital; c3, 3rd cervical centrum; d, dentary; eo-op, exoccipital-opisthotic complex; f, frontal; fo, fontanelle; j, jugal; m, maxilla; n, nasal; p, parietal; par, prearticular; pm, premaxilla; po, postorbital; pof, postfrontal; prf, prefrontal; q, quadrate; r3, 3rd cervical rib; sa, surangular; so, supraoccipital; sq, squamosal. The red arrow marks the pit on the premaxilla-maxilla suture. Scale bars equal 1 mm

 

Dianmeisaurus mutaensis sp. nov.

Type locality: Muta Village, Luxi County, Yunnan Province, China.

Type horizon: Upper Member of Guanling Formation, Anisian, Middle Triassic.

Etymology: Named after Muta village where the holotype was collected.

Diagnosis: A pachypleurosaur with following autapomorphies among pachypleurosaurs: 23 cervical vertebrae, 20 dorsal vertebrae, and two sacral vertebrae; postfrontal extending posteriorly to a level beyond the middle of parietal; last dorsal rib stout and shorter than the first sacral rib; phalangeal formula of manus and pes 2-3-4-4-2 and 1-2-3-4-3 respectively. In addition to the above-mentioned autapomorphies, Dianmeisaurus mutaensis also differs from D. gracilis in the following morphological characters: maxilla enters the external naris; anterior process of the frontal does not extend beyond the anterior margin of the orbit; postfrontal excluded from the upper temporal fenestra; coronoid process absent.

Yi-Wei Hu, Qiang Li and Jun Liu. 2024. A New pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of southwestern China and its phylogenetic and biogeographic implications. Swiss Journal of Palaeontology. 143. DOI: doi.org/10.1186/s13358-023-00292-4

[Paleontology • 2024] The Marine Conservation Deposits of Monte San Giorgio (Switzerland & Italy): the Prototype of Triassic Black Shale Lagerstätten

 

The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten.

in Klug, Spiekman, Bastiaans, Scheffold et Scheyer, 2024.

 DOI: 10.1186/s13358-024-00308-7 

Abstract

Marine conservation deposits (‘Konservat-Lagerstätten’) are characterized by their mode of fossil preservation, faunal composition and sedimentary facies. Here, we review these characteristics with respect to the famous conservation deposit of the Besano Formation (formerly Grenzbitumenzone; including the Anisian–Ladinian boundary), and the successively younger fossil-bearing units Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio (Switzerland and Italy). We compare these units to a selection of important black shale-type Lagerstätten of the global Phanerozoic plus the Ediacaran in order to detect commonalities in their facies, genesis, and fossil content using principal component and hierarchical cluster analyses. Further, we put the Monte San Giorgio type Fossillagerstätten into the context of other comparable Triassic deposits worldwide based on their fossil content. The results of the principal component and cluster analyses allow a subdivision of the 45 analysed Lagerstätten into four groups, for which we suggest the use of the corresponding pioneering localities: Burgess type for the early Palaeozoic black shales, Monte San Giorgio type for the Triassic black shales, Holzmaden type for the pyrite-rich black shales and Solnhofen type for platy limestones.

Keywords: Konservat-Lagerstätten, Taphonomy, Marine reptiles, Exceptional preservation

Three important marine reptiles from the Middle Triassic of Monte San Giorgio with their reconstructions, recently crafted by Beat Scheffold. 

A Tanystropheus, PIMUZ T 2817. B Cyamodus, PIMUZ T58. C, Mixosaurus, PIMUZ T 4923 (top) and PIMUZ T 4376 (bottom)

Fossilized foetuses inside the mother, examples from the Middle Triassic of Monte San Giorgio. A Mixosaurus, PIMUZ T 4830 (e.g., Brinkmann, 1996; Miedema et al., 2023). B Saurichthys, PIMUZ T 3917 (e.g., Maxwell et al., 2018)

Fossilized mollusks from the Middle Triassic of Monte San Giorgio (see Rieber, 1969, 1970, 1973; Pieroni, 2022). 

A, Proarcestes extralabiatus, internal mould. B, Repossia acutenodosa, silicified internal mould. C, Proarcestes extralabiatus, external mould. D, Phragmoteuthis ticinensis with complete arm crown, cephalic cartilage, oesophagus and ink sac. E, Daonella caudata. F, Pleuronautilus sp., internal mould

Some animals from Monte San Giorgio.
 Note that not all of the depicted taxa may have co-occurred in time or in space (habitat depth, etc.). At Monte San Giorgio, the water depth was likely greater then shown in these images.
A Meride Limestone (Ladinian). B Besano Formation (Anisian)

Reconstructions by Beat Scheffold.  

Conclusions: 

The conservation deposits of Anisian and Ladinian age of Monte San Giorgio, comprising the Besano Formation, Cava inferiore, Cava superiore, Cassina Beds, and the Kalkschieferzone, represent some of the first black shale conservation deposits of Triassic age that were thoroughly studied. Now, after a century of excavations and more than a century of research, these deposits begin to enjoy global scientific recognition (e.g., Etter, 2002a; Rieppel, 2019), and continue to produce valuable new information about the palaeobiology and evolution of Triassic vertebrates today.

With this paper, we want to highlight the key role of the conservation deposits of Monte San Giorgio: comparable to the pioneer role of the Burgess Shale for the Cambrian Lagerstätten or Solnhofen for the Mesozoic platy limestones, we highlight the pioneer role of the Besano Formation in particular as the prototype for Triassic Lagerstätten. Our simple comparison of 45 Fossillagerstätten worldwide employing principal component and hierarchical cluster analyses of 32 traits based on the ...

Christian Klug, Stephan N. F. Spiekman, Dylan Bastiaans, Beat Scheffold and Torsten M. Scheyer. 2024. The Marine Conservation Deposits of Monte San Giorgio (Switzerland, Italy): the Prototype of Triassic Black Shale Lagerstätten.  Swiss Journal of Palaeontology. 143, 11. DOI: doi.org/10.1186/s13358-024-00308-7 

 

[Paleontology • 2024] Oldest southern Sauropterygian reveals early Marine Reptile Globalization

  Morphology and biogeographic context of GNS CD 540, the oldest Southern Hemisphere sauropterygian.

in Kear, Roberts, Young, Terezow, Mantle, Barros & Hurum, 2024. 

DOI: 10.1016/j.cub.2024.03.035

Artwork: Johan Egerkrans

Summary

Sauropterygians were the stratigraphically longest-ranging clade of Mesozoic marine reptiles with a global fossil record spanning ∼180 million years1. However, their early evolution has only been known from what is now the Northern Hemisphere, extending across the northern and trans-equatorial western margins of the Tethys paleo-ocean after the late-Early Triassic (late Olenekian, ∼248.8 million years [Ma] ago), and via possible trans-Arctic migration to the Eastern Panthalassa super-ocean prior to the earliest Middle Triassic (Olenekian–earliest Anisian, ∼247 Ma). Here, we describe the geologically oldest sea-going reptile from the Southern Hemisphere — a nothosaur (basal sauropterygian) from the Middle Triassic (Anisian, after ∼246 Ma) of New Zealand. Time-scaled ancestral range estimations thus reveal an unexpected circum-Gondwanan high-paleolatitude (>60° S7) dispersal from a northern Tethyan origination center. This coincides with the adaptive diversification of sauropterygians after the end-Permian mass extinction8 and suggests that rapid globalization accompanied their initial radiation in the earliest Mesozoic.

  Morphology and biogeographic context of the oldest Southern Hemisphere sauropterygian.
(A) mCT image of the GNS CD 540 dorsal vertebra in posterior view.
(B) Time-scaled Bayesian phylogeny (Figure S1G) of Nothosauroidea (silhouettes) with estimated ancestral ranges (pie charts), dispersal (orange circles) and vicariance (blue circles) events (Table S1). Node numbers indicate geographic ranges (red) and percent (>50%) support (black) for ancestral range estimations.
(C) Middle Triassic global map showing ancestral ranges (solid arrows) and possible dispersal routes (dashed arrows; modified from maps compiled by Colorado Plateau Geosystems Inc. https://deeptimemaps.com/).
(D) Middle Triassic southern polar map with occurrence of GNS CD 540 (red star).

Anatomical abbreviations: as, centrum articular surface; le, laterally expanded neural arch contact; ns, neural spine; tp, transverse process; zg, zygantrum; zy, postzygapophysis. 

Geographic ranges: (1) Northeastern to Northwestern Tethys; (2) Northwestern Tethys to Eastern Panthalassa; (3) Northern Tethys to Southern Polar Panthalassa; (4) Northern Tethys to Southwestern Tethys.

Reconstruction of the New Zealand nothosaur. The oldest sea-going reptile from the Southern Hemisphere.

Artwork: Johan Egerkrans

 

 Benjamin P. Kear, Aubrey J. Roberts, George Young, Marianna Terezow, Daniel J. Mantle, Isaias Santos Barros and Jørn H. Hurum. 2024. Oldest southern Sauropterygian reveals early Marine Reptile Globalization. Current Biology. 34(12);  R562-R563. DOI: 10.1016/j.cub.2024.03.035

[Paleontology • 2024] Franconiasaurus brevispinus • Exquisite Skeletons of A New transitional Plesiosaur fill gap in the Evolutionary History of plesiosauroids

  Franconiasaurus brevispinus 

Sachs, Eggmaier & Madzia, 2024

DOI: 10.3389/feart.2024.1341470

  (artwork by Joschua Knüppe).

Plesiosaurs are Mesozoic reptiles fully adapted to an aquatic lifestyle. Throughout their evolutionary history exceeding 140 million years plesiosaurs dispersed globally, achieved substantial diversity, occupied a variety of ecological niches, and experienced multiple faunal turnovers. Of those, the Early/Middle Jurassic transition event (∼175–171 Mya) has recently became of increased interest because it apparently profoundly affected all three major lineages of plesiosaurs. Once dominant Rhomaleosauridae started to vanish, while Pliosauridae and Plesiosauroidea diversified and gave rise to several clades that flourished for tens of millions of years. Here, we report exquisite, three-dimensionally preserved skeletons of a new plesiosaur from the Lower Jurassic of Germany. Franconiasaurus brevispinus gen. et sp. nov. lived during the late Toarcian (∼175 Mya), near the onset of the Early–Middle Jurassic turnover. Franconiasaurus displays an intriguing mixture of features, combining characters almost uniformly distributed among early plesiosaurs with those typically observed in later-diverging members of the clade. Phylogenetic analyses firmly place Franconiasaurus as the sister taxon to Cryptoclidia, bridging an evolutionary gap between early plesiosauroids, such as Plesiosaurus-like forms and microcleidids, and later-diverging representatives of the clade, such as cryptoclidids, leptocleidians, and elasmosaurids.

  Diagnostic skeletal elements of the type specimen of Franconiasaurus brevispinus gen. et sp. nov. (BT 011224.00).
(A) main slab showing partly articulated skeleton in dorsal view. Posterior part of right mandibular ramus in (B) lateral and (C) dorsal aspect; anterior cervical vertebra (D) in articular and (E) lateral view; (F) posterior cervical vertebra in lateral view; (G) cervical rib in dorsolateral view; (H) dorsal vertebra in posterior view; (I) left scapula in medial view; (J) right coracoid in supposed dorsal view; (K) left humerus in dorsal view; (L) left femur with adjacent epipodials in dorsal view; and (M) left ilium in lateral view.

Systematic paleontology

Plesiosauria de Blainville, 1835 

Plesiosauroidea Gray, 1825 

Franconiasaurus gen. nov.

 

Etymology—After the region of Franconia (Franken in German), located in the northern part of Bavaria in southern Germany, where the specimens were found; and “σαῦρος” (sauros), Greek for “reptile”.

Franconiasaurus brevispinus sp. nov.

Diagnosis—A plesiosauroid diagnosed through the following unique combination of characters: surangular with transversely narrow dorsal side and convex lateral side, lacking a longitudinal lateral through; cervical centra amphicoelous, being wider than long/high; cervical zygapophyses narrower than centra, having planar facets and being not connected for most of their length; anterior cervical neural spines curve posterodorsally, posterior cervical neural spines inclined straight posterodorsally; posterior cervical and dorsal neural spines only moderately higher than long (height/length ratio approximately 1.6); cervical ribs with reduced anterior processes; dorsal process of scapula with slightly convex medial side, lacking a buttress like medial enforcement; long intercoracoid symphysis, coracoids being only slightly separated posteromedially; coracoid cornu does not extend to the level of the glenoid; ilium shaft straight, dorsal and ventral ends of ilium perpendicular to one another; femora and humeri subequal in length; propodials moderately elongate (length/width ratio 1.7); radius and tibia subquadratic with concave pre- and postaxial sides.

Type specimen—BT 011224.00, nearly complete, three-dimensionally preserved, and partly articulated skeleton.

 

Horizon and locality—The specimens were excavated in 2005 (BT 011241.00) and between 2014 and 2018 (BT 011224.00) by one of us (S.E.) in the lower section of the Jurensismergel Formation (Grammoceras thouarsense Zone), upper Toarcian, Lower Jurassic, in the Mistelgau fossil pit, Bayreuth District, Bavaria, Germany. For detailed information on the geological and stratigraphic settings see Electronic Supplementary Material S2.

Etymology—The name brevispinus refers to the low neural spines in the posterior cervical and dorsal vertebrae.

 Life reconstruction of Franconiasaurus brevispinus gen. et sp. nov. 

  (artwork by Joschua Knüppe).

Sven Sachs, Stefan Eggmaier and Daniel Madzia. 2024. Exquisite Skeletons of A New transitional Plesiosaur fill gap in the Evolutionary History of plesiosauroids. Front. Earth Sci. 12. DOI: 10.3389/feart.2024.1341470

[Paleontology • 2023] Lorrainosaurus keileni • The Rise of Macropredatory Pliosaurids near the Early-Middle Jurassic Transition

 Lorrainosaurus keileni   

 in Sachs, Madzia, Thuy & Kear, 2023.

 DOI: 10.1038/s41598-023-43015-y 

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artwork: Joschua Knüppe

Abstract

The emergence of gigantic pliosaurid plesiosaurs reshaped the trophic structure of Mesozoic marine ecosystems, and established an  ~ 80 million-year (Ma) dynasty of macropredatory marine reptiles. However, the timescale of their ‘defining’ trait evolution is incompletely understood because the fossil record of gigantic pliosaurids is scarce prior to the late-Middle Jurassic (Callovian),  ~ 165.3 Ma. Here, we pinpoint the appearance of large body size and robust dentitions to early-Middle Jurassic (Bajocian) pliosaurids from northeastern France and Switzerland. These specimens include a new genus that sheds light on the nascent diversification of macropredatory pliosaurids occurring shortly after the Early-Middle Jurassic transition, around  ~ 171 Ma. Furthermore, our multivariate assessment of dental character states shows that the first gigantic pliosaurids occupied different morphospace from coeval large-bodied rhomaleosaurid plesiosaurs, which were dominant in the Early Jurassic but declined during the mid-Jurassic, possibly facilitating the radiation and subsequent ecomorph acme of pliosaurids. Finally, we posit that while the emergence of macropredatory pliosaurids was apparently coordinated with regional faunal turnover in the epeiric basins of Europe, it paralleled a globally protracted extinction of other higher trophic-level marine reptiles that was not completed until after the earliest-Late Jurassic,  ~ 161.5 Ma.

Skeletal remains of the holotype (MNHNL BU159) of Lorrainosaurus keileni.
(a) Reconstruction in lateral view showing recovered elements. (b) Tooth crown with root. (c) Posterior section of mandible in lateral view. (d) Glenoid section of mandible in articular view. (e) Complete mandible in ventral view. (f) Enlargement of the mandibular symphysis. (g) Coracoid in dorsal view.

  

Plesiosauria de Blainville, 1835 

Pliosauridae Seeley, 1874 

Thalassophonea Benson & Druckenmiller, 2014 

Lorrainosaurus gen. nov.

Etymology: Derived from ‘Lorraine’, for the type locality; and ‘σαῦρος’ (sauros), Greek for ‘reptile’.

Type species: Lorrainosaurus keileni (Godefroit, 1994) 

Type locality and stage: A temporary road cutting between Montois-la-Montagne and Sainte-Marie-aux-Chênes ~ 18 km northeast of Metz in Lorraine, northeastern France. These deposits form part of the Marnes de Gravelotte regional lithostratigraphical unit correlated with the upper Bajocian (mid-Middle Jurassic) Parkinsonia parkinsoni Zone.

Diagnosis: Large-bodied thalassophonean pliosaurid autapomorphically distinguished by a transversely broad, ‘wedge-shaped’ splenial contact that extends anteriorly to the level of the fourth mandibular alveolus. Lorrainosaurus keileni also displays a unique character state combination: (1) laterally expanded and posteriorly constricted ‘spatulate’ symphyseal section of the mandible bearing five to six alveoli; (2) lateral trough on the mandible anterior to the glenoid fossa; (3) a retroarticular process that is shorter than the glenoid fossa; (4) retroarticular process with posteroventrally oriented dorsoventral long axis and slightly posteromedially inflected mediolateral long axis; (5) wide posteromedial seperation of the coracoids; (6) posterolateral edge of the coracoid (cornu) projecting beyond the level of the glenoid fossa (Fig. 1).

 

 Sven Sachs, Daniel Madzia, Ben Thuy and Benjamin P. Kear. 2023. The Rise of Macropredatory Pliosaurids near the Early-Middle Jurassic Transition. Scientific Reports. 13: 17558. DOI: 10.1038/s41598-023-43015-y

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