Palaeoecology of a late Jurassic echinoderm community from the Swiss Jura mountains

The region of Porrentruy (Swiss Jura Mountains) is known for its rich and diverse assemblage of Late Jurassic coastal marine turtles (Thalassochelydia). Dominated by the “Plesiochelyidae”, this assemblage also includes representatives of the two other thalassochelydian groups, the “Thalassemydidae” and “Eurysternidae.” In this study, we present new shell-based material from Porrentruy referable to eurysternids. One specimen represents a juvenile individual or a relatively small taxon, and is notably characterized by a well fenestrated plastron exhibiting a wider than long central plastral fontanelle. Two other specimens are much larger and possibly represent the largest eurysternids known to date. The fourth specimen is characterized by a unique plastral morphology otherwise only known in very small juveniles. This is the first time this unique plastral morphology is known to persist in an adult or subadult. The new material described herein represents at least three distinct taxa, all of them probably new. However, we refrain from naming new species based on this incomplete material in order to avoid adding confusion to an already complex taxonomical situation. This study provides new insights into the great diversity of eurysternids during the Late Jurassic.

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Under the feet of sauropods: A trampled coastal marine turtle from the Late Jurassic of Switzerland?

10.31233/osf.io/2atnq ◽

2019 ◽

Author(s):

Christian Püntener ◽

Jean-Paul Billon-Bruyant ◽

Daniel Marty ◽

Géraldine Paratte

Keyword(s):

Tidal Flat ◽

Late Jurassic ◽

The State ◽

Marine Turtle ◽

Jura Mountains ◽

Turtle Shell ◽

Coastal Marine ◽

Swiss Jura

Recent excavations from the “Paléontologie A16” project brought to light thousands of dinosaur footprints and numer-ous turtle remains from the Late Jurassic of Porrentruy (Swiss Jura Mountains). While most fossil turtles (Thalassochelydia) were found in marly layers that were deposited in a coastal marine paleoenvironment, the dinosaur (theropods and sauropods) tracks were found in laminites that were deposited in a tidal flat environment. Despite extensive explo-ration, very few fossils were found in these dinosaur track-bearing laminites. On one occasion, a sub-complete turtle shell (Plesiochelys bigleri) was discovered within the laminites, embedded just beneath an important sauropod track level. The state of preservation of this specimen suggests that the turtle died on the tidal flat and was quickly buried. This is the first evidence that these turtles occasionally visited tidal flat paleoenvironments. Moreover, the particular configuration of the fossil turtle suggests that the shell was possibly trodden on by a large sauropod dinosaur.

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Thalassemys bruntrutanan. sp., a new coastal marine turtle from the Late Jurassic of Porrentruy (Switzerland), and the paleobiogeography of the Thalassemydidae

PeerJ ◽

10.7717/peerj.1282 ◽

2015 ◽

Vol 3 ◽

pp. e1282 ◽

Cited By ~ 14

Author(s):

Christian Püntener ◽

Jérémy Anquetin ◽

Jean-Paul Billon-Bruyat

Keyword(s):

Late Jurassic ◽

Marine Turtle ◽

Jura Mountains ◽

Marine Turtles ◽

The Past ◽

Coastal Marine ◽

New Material ◽

Swiss Jura ◽

Nw Switzerland ◽

A New Species

Background.The Swiss Jura Mountains are a key region for Late Jurassic eucryptodiran turtles. Already in the mid 19th century, the Solothurn Turtle Limestone (Solothurn, NW Switzerland) yielded a great amount of Kimmeridgian turtles that are traditionally referred to Plesiochelyidae, Thalassemydidae, and Eurysternidae. In the past few years, fossils of these coastal marine turtles were also abundantly discovered in the Kimmeridgian of the Porrentruy region (NW Switzerland). These findings include numerous sub-complete shells, out of which we present two new specimens ofThalassemys(Thalassemydidae) in this study.Methods.We compare the new material from Porrentruy to the type speciesTh. hugii, which is based on a well preserved specimen from the Solothurn Turtle Limestone (Solothurn, Switzerland). In order to improve our understanding of the paleogeographic distribution ofThalassemys, anatomical comparisons are extended toThalassemysremains from other European countries, notably Germany and England.Results.While one of the twoThalassemysspecimens from Porrentruy can be attributed toTh. hugii, the other specimen represents a new species,Th. bruntrutanan. sp. It differs fromTh. hugiiby several features: more elongated nuchal that strongly thickens anterolaterally; wider vertebral scales; proportionally longer plastron; broader and less inclined xiphiplastron; wider angle between scapular process and acromion process. Our results show thatTh. hugiiandTh. bruntrutanaalso occur simultaneously in the Kimmeridgian of Solothurn as well as in the Kimmeridgian of England (Kimmeridge Clay). This study is an important step towards a better understanding of the paleobiogeographic distribution of Late Jurassic turtles in Europe.

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