Ichthyosaurs Research Articles

Stenopterygiids from the lower Toarcian of Beaujolais and a chemostratigraphic context for ichthyosaur preservation during the Toarcian Oceanic Anoxic Event

Stenopterygiids from the lower Toarcian of Beaujolais and a chemostratigraphic context for ichthyosaur preservation during the Toarcian Oceanic Anoxic Event

PREDATORS AND PREYS: A CASE HISTORY FOR SAURICHTHYS (COSTASAURICHTHYS) COSTASQUAMOSUS RIEPPEL, 1985 FROM THE LADINIAN OF LOMBARDY (ITALY)

A large specimen of Saurichthys (Costasaurichthys) costasquamosus from the lower Ladinian of the Northern Grigna mountain is described. It is an incomplete specimen, lacking the caudal region, and showing gut content. This latter consists of totally scattered remains of at least two specimens of adult Ctenognathichthys bellottii , a medium size fish quite common in this fossil assemblage. Saurichthys has been always considered an active predator on small fishes, but it cannot be the case for this specimen, with remains in the gut are totally disarticulated and evenly scattered all along the abdomen. Scavenging on floating carcasses is proposed, the hypothesis being also supported by the common preservation of Ctenognathichthys as incomplete individuals. Although the Saurichthys specimen shows some ‘in situ’ disarticulation, caudal region elements are totally missing on the slab yielding the anterior part of the fish. As for other large Saurichthys specimens from the same site, it is supposed that this is the result of a predation by a much larger marine organism, possibly an ichthyosaur.

Large-sized ichthyosaurs from the Lower Saurian niveau of the Vikinghøgda Formation (Early Triassic), Marmierfjellet, Spitsbergen

Large-sized ichthyosaurs from the Lower Saurian niveau of the Vikinghøgda Formation (Early Triassic), Marmierfjellet, Spitsbergen

The first known neonate Ichthyosaurus communis skeleton: a rediscovered specimen from the Lower Jurassic, UK

Numerous specimens of Ichthyosaurus are known, but only very few small examples (total length of <1 m) have been assigned beyond Ichthyosaurus sp. Here, we report on a very small specimen (preflexural length of 560 mm) that can be unequivocally assigned to Ichthyosaurus communis due to possessing a unique combination of diagnostic skull and postcranial characters that are found in larger examples of the species. Furthermore, the specimen is identified as a neonate because of the small size, large sclerotic ring relative to the orbital region, and poorly ossified (highly cancellous) bones of the skull and postcranium. It is not an embryo as it is not preserved within an adult specimen and stomach contents are clearly evident. This is therefore the first neonate Ichthyosaurus communis skeleton to be described. The specimen, in the Lapworth Museum of Geology, University of Birmingham, has no provenance data associated with it. A microfossil analysis of the matrix in which the ichthyosaur skeleton is preserved strongly suggests a stratigraphic range of uppermost Hettangian to lowermost Sinemurian age (Lower Jurassic), but does not provide any geographical information.

A taxonomic reassessment of Ichthyosaurus communis and I. intermedius and a revised diagnosis for the genus

Ichthyosaurus communis De la Beche & Conybeare, 1821 and I. intermedius Conybeare, 1822 have been considered synonymous by some researchers, but distinct species by others. The distinction between the two species was originally based on tooth morphology, which has been shown to vary ontogenetically as well as within an individual. Subsequent literature of the nineteenth century did not propose adequate diagnostic features to distinguish the two species. In addition, illustrations suggest that both species were confused with I. breviceps, which was defined over 50 years later. The type specimens of both species are missing, making the problem unresolvable. However, a neotype was designated for I. communis to retain the widely used species name and to stabilize the taxonomy. The species can be recognized by a symmetric, triangular maxilla with long processes and a large, broad, triradiate lacrimal, as well as a unique combination of other characters. The neotype shares numerous features with the I. intermedius ‘type figure’, including the morphologies of the maxilla, prefrontal, lacrimal, jugal and postorbital, such that the two are nearly indistinguishable. Thus I. intermedius must be considered a synonym of I. communis. Ichthyosaurus communis can be identified from the Lyme Regis-Charmouth coast, west Dorset; the ?Whitby coast of Yorkshire; and probably from Street, Somerset. The stratigraphical range of I. communis is at least lower Hettangian to lower Sinemurian.

Ichthyosaurs from the Jurassic of Skye, Scotland

Fossils of Mesozoic vertebrates are rare in Scotland, particularly specimens of marine reptiles such as plesiosaurs and ichthyosaurs. We describe a suite of ichthyosaur fossils from the Early to Middle Jurassic of Skye, which to our knowledge are the first ichthyosaurs from Scotland to be described and figured in detail. These fossils span approximately 30 million years, from the Sinemurian to the Bathonian, and indicate that ichthyosaurs were a major component of Scottish marine faunas during this time. The specimens include isolated teeth that could represent the most northerly known occurrences of the widespread Sinemurian species Ichthyosaurus communis , a characteristic component of the famous Lyme Regis faunas of England, suggesting that such faunas were also present in Scotland during the Early Jurassic. An associated humerus and vertebrae from Toarcian–Bajocian-aged deposits are named as a new genus and species of basal neoichthyosaurian, Dearcmhara shawcrossi . The taxonomic affinities of this taxon, which comes from a critical but poorly sampled interval in the fossil record, suggest that non-ophthalmosaurid neoichthyosaurians dominated European assemblages around the Early–Middle Jurassic boundary, and were later replaced by ophthalmosaurids, whose radiation likely took place outside Europe. Many of these specimens were collected by amateurs and donated to museum collections, a co-operative relationship essential to the preservation of Scotland’s fossil heritage.

A new specimen of Ichthyosaurus communis from Dorset, UK, and its bearing on the stratigraphical range of the species

This paper describes a new ichthyosaur specimen from the Stonebarrow Marls Member (Charmouth Mudstone Formation) of Charmouth, Dorset. It is substantially complete and various characters of the skull (snout ratios and basioccipital morphology) and appendicular skeleton (the number of digits on the hind paddle, which can be used to infer the number of digits on the front paddle) indicate that the specimen is referable to Ichthyosaurus communis. This provides the first direct evidence for the presence of I. communis in the Pliensbachian, extending the stratigraphic range of the species. The specimen also preserves a probable gullet content, which demonstrates that fish formed part of the diet of this individual.

A large skull of Ichthyosaurus (Reptilia: Ichthyosauria) from the Lower Sinemurian (Lower Jurassic) of Frick (NW Switzerland)

An incomplete skull of an ichthyosaur attributed to Ichthyosaurus communis Conybeare 1822 is reported from the Lower Sinemurian calcarenites (upper part of the “Beggingen Member”, previously “Arietenkalk”, Semicostatum zone) of Frick (Canton Aargau, northern Switzerland). It is the first record of this genus and species in Switzerland, and the first definite record of the genus Ichthyosaurus from central Europe. This species was hitherto only known from Lower Hettangian to Lower Sinemurian deposits of England and Upper Sinemurian sediments of Belgium. The specimen represents a particularly large individual that considerably exceeds all known English representatives of this species in skull length, and is closest in size to the single specimen from Belgium. Unusual anatomical features include a strong coossification of the posterior skull-roof bones (probably a result of an old ontogenetic age) and a very elongate and deep excavatio internasalis. A short overview of substantial Swiss Mesozoic ichthyosaur finds is provided. The Jurassic record appears very patchy so far, but has been considerably improved thanks to recent discoveries.

Lost &amp; Found: 225. Ichthyosaurus communis missing from Trinity College, Dublin

Patrick N. Wyse Jackson (Curator, Geological Museum, Dept. of Geology, Trinity College, Dublin 2, Ireland) writes: 'I am attempting to trace the wherabouts of an ichthyosaur that is missing from the collections of the Geological Museum, Dept. of Geology, Trinity College, Dublin. It is an example of Ichthyosaurus communis from the Lias of Lyme Regis. The specimen is quite distinctive in that both sides of the lower jaw are visible, and the tip of the tail is flexed downwards. It was figured by S. Haughton in his Manual of Geology (1865, fig. 35, opp. p. 272) (reproduced here as Fig. 1); a second ichthyosaur figured on this page (Fig. 36)...

The Cranial Moorphology of the Lower Liassic Latipinnate Ichthyosaurs of England

The Cranial Moorphology of the Lower Liassic Latipinnate Ichthyosaurs of England

Auctions: Ichthyosaur under the Hammer

Auctions: Ichthyosaur under the Hammer

New Zealand triassic saurians

Abstract Ichthyosaur gen. et sp. indet. from Upper Otamitan (late Carnian) strata, Hokonui Hills, is figured and briefly described. An occurrence of a suspected plesiosaur bone from Oretian (early Carnian) strata on the Marakopa coast is recorded. The status of the only other recorded occurrence of a Triassic saurian in New Zealand, Mixosaurus(?) hectori Lydekker, is briefly reviewed.

The Tredington “Ichthyosaur”

A note stating the conclusions reached from an examination of the supposed ichthyosaur in a slab flooring the porch of Tredington church, Gloucestershire, England.

The Pendulation Theory

IN NATURE of April 2, 1908, the reviewer of my “Pendulations theorie”, Mr. R. L., directed attention to the map which shows the distribution of the ichthyosaurs, because I have left out the African ones. He therefore thinks it difficult to commit himself to an opinion on the theory.

Notice of the Discovery of the Remains of the Ichthyosaurus in Missouri, N. A.

Notice of the Discovery of the Remains of the Ichthyosaurus in Missouri, N. A.