RESTUDY OF SHANTUNGOSUCHUS BRACHYCEPHALUS YOUNG, 1982

ThreespecieshavebeenreferredtoShantungosuchustodate.ThetypespeciesS.chuhsienensis(Young,1961)isrepresentedbyanarticulatedskeletonpreservedasanimpressionofitsventralsurface.S.hangjinensiswasrecentlydescribedbyWuetal.(1994)onthebasisofanincompleteskull(withthemandible)andthepartofthepostcranialskeleton.ThethirdspeciesisS.brachycephalus,whichwillberestudiedinthepresentpaper'sbrachycephaluswaserectedbyYoungforaspecimen,consistingofpartialskullandsomepostcranialelements(V4020).Itwaspublishedinon…     

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.     

Sunosuchus (Archosauria, Crocodyliformes) from the Toutunhe Formation (Middle Jurassic) of the Southern Junggar Basin (Xinjiang, NW-China)

A new specimen of the widespread Middle Jurassic to Lower Cretaceous Asian gonipholidid crocodilian genus Sunosuchus is described on the basis of a partial skeleton from the Upper Toutunhe Formation (Middle Jurassic, ?Bathonian-Callovian) of Liuhonggou, SW of Urumqi, Xinjiang Uygur Autonomous Region, People’s Republic of China. The specimen is represented by a partial mandible, teeth, vertebrae, limb and girdle bones and osteoderms. It can be distinguished from other nominal species of the genus by a unique combination of characters: slightly heterodontous dentition, strongly sculptured posteroventral part of the mandible, short fenestra mandibularis, convex dorsal surface of the retroarticular process, keeled cervical vertebral centra and ventral osteoderms with a distinctive sculpture of wide pits and narrow ridges. The heterodontous dentition is a potential autapomorphy of this form. The new specimen is closest in morphology to material described recently from the Callovian of Kirghisia as Sunosuchus sp. It represents the second Middle Jurassic record of the genus, the first crocodile from the Toutunhe Formation, the first substantial crocodile find from the Mesozoic of the Southern Junggar Basin, and the first Middle Jurassic record of Sunosuchus from China. This extends both the paleobiogeographical distribution of the genus in Asia and its stratigraphic distribution in China considerably.     

An amioid fish (Neopterygii, Amiiformes) from the Late Jurassic of the Iberian Peninsula

The first record of the bowfin order Amiiformes in the Late Jurassic of Portugal is reported. The single specimen comes from the Guimarota coal mine near Leiria in the Lusitanian basin. Here, Kimmeridgian strata that yielded abundant teeth, spines, and scales of selachians and actinopterygians are exposed below ground. The specimen described herein is the only disarticulated fish remain from this locality. It consists of jaw elements, parts of the palatoquadrate and opercular apparatus, an element of the postorbital series and some additional postcranial parts. The systematic position of the new specimen is discussed. The combination of characters allows assignment to the Amioidea rather than to other amiiform groups. Therefore, the specimen constitutes the first undoubted record of an amioid in the Late Jurassic of the Iberian Peninsula and contributes to the knowledge of Late Jurassic amiiform distribution patterns.     

The postcranial skeleton of the Lower Jurassic eosuchian Gephyrosaurus bridensis

The postcranial skeleton of the reptile Gephyrosaurus bridensis is described. The material was extracted from the Lower Jurassic fissure infillings of South Wales and comprises the broken and dissociated bones of many different individuals. The skeleton, like the skull, retains many primitive features which justify the inclusion of Gephyrosaurus within the Eosuchia. A comparison of the skeleton with that of other genera supports the conclusion that Gephyrosaurus represents a separate eosuchian lineage. The skeleton is that of a small, unspecialized terrestrial reptile which could move quickly in pursuit of prey.     

Le Crocodilien Steneosaurus (Mesosuchia,Teleosauridae) dans le Jurassique supérieur franc-comtois (Jura,France)

Two new fossil vertebrate localities have been discovered close to each other in the Upper Jurassic (Effingen beds, Upper Oxfordian) of the Southern Jura department (France). One of the localities have yielded an incomplete skeleton of the crocodilian Steneosaurus (including a well preserved skull), as well as fish remains and an abundant invertebrate fauna. The second locality has mainly yielded various fragmentary bones of Steneosaurus. This is the first discovery of well preserved crocodilian remains in the Oxfordian of the Jura.     

AN ALMOST COMPLETE JUVENILE SPECIMEN OF THE CHELONIID TURTLE CTENOCHELYS STENOPORUS (HAY, 1905) FROM THE UPPER CRETACEOUS NIOBRARA FORMATION OF KANSAS,USA

Abstract: A new, unusually well‐preserved juvenile specimen of Ctenochelys stenoporus from the Niobrara Formation is described. The skull has come apart at its sutures and all bones of the braincase and ear region are preserved three‐dimensionally. This allows a detailed reconstruction of the important brain structures of a basal juvenile cheloniid turtle. It is compared with adult Ctenochelys specimens, and the major ontogenetic changes in the skull and postcranial skeleton are described. Furthermore, the specimen is compared with other fossil and extant cheloniids with well‐known braincases and the differences between basal and advanced cheloniids turtles are specified.     

Probable crocodilian tracks and traces from the Morrison Formation (Upper Jurassic) of eastern Utah

A tetradactyl pes impression and tridactyl manus impression are described as the type specimen of Hatcherichnus sanjuanensis ichnogen. et ichnosp. nov., a probable large crocodilian ichnite from the Salt Wash Member of the Upper Jurassic Morrison Formation in eastern Utah. A similar pes track from the Morrison Formation at Garden Park, Colorado, may also belong to this ichnogenus. The type specimen from Utah consists of plaster replicas of natural casts of a left pes impression and a left manus impression. Associated with the type specimen were possible tail and body drag impressions. The tracks do not appear to be part of a walking trackway and may be swim tracks associated with an animal in shallow water. The tracks occur at a visible contact between slightly fining‐upward channel sandstone units.     

三列齿类爬行动物化石在新疆的发现

本文报道的三列齿类化石是该类动物在我国西北地区之首次出现,与四川自贡所产大山铺恐龙动物群中的自贡似卞氏兽(Bienotheroides zigongensis)归同属同种,故认为五彩湾组可与下沙溪庙组相对比。新标本的发现在若干形态特征上补充了以往记述之不足。     

四川中侏罗世的龟化石

本文对产自四川自贡中侏罗世的三件龟甲标本作了鉴定,认为均可归成渝龟属(Chengyuchelys)。一为自贡成渝龟,新种(Chengyuchelys zigongensis,sp.nov.),一为似贝氏成渝龟(C.baenoides, Young et Chow),一为成渝龟未定种(Chengyuchelys sp.)。在形态描述的基础上,讨论了成渝龟属的系统分类。     

First diagnostic marine reptile remains from the aalenian (middle jurassic): a new ichthyosaur from southwestern Germany

Background

The Middle Jurassic was a critical time in the evolutionary history of ichthyosaurs. During this time interval, the diverse, well-studied faunas of the Lower Jurassic were entirely replaced by ophthalmosaurids, a new group that arose sometime prior to the Aalenian-Bajocian boundary and by the latest middle Jurassic comprised the only surviving group of ichthyosaurs. Thus, the Middle Jurassic Aalenian-Bathonian interval (176–165 million years ago) comprises the time frame during which ophthalmosaurids not only originated but also achieved taxonomic dominance. However, diagnostic ichthyosaur remains have been described previously from only a single locality from this interval, from the Bajocian of Argentina.

Methodology/Principal Findings

In this paper, we describe a new species of ichthyosaur based on a partial articulated specimen from the Middle Jurassic of southwestern Germany. This specimen was recovered from the Opalinuston Formation (early Aalenian) and is referable to Stenopterygius aaleniensis sp. nov. reflecting features of the skull and forefin. The genus Stenopterygius is diverse and abundant in the Lower Jurassic of Europe, but its presence has not previously been confirmed in younger (Middle Jurassic) rocks from the northern hemisphere.

Conclusions/Significance

This specimen represents the only diagnostic ichthyosaur remains reported from the Aalenian. It bears numerous similarities in size and in morphology to the Lower Jurassic species of the genus Stenopterygius and provides additional evidence that the major ecological changes hypothesized to have occurred at the end of the Toarcian took place sometime after this point and most likely did not occur suddenly. There is currently no evidence for the presence of ophthalmosaurids in the northern hemisphere during the Aalenian-Bathonian interval.     

Pterosaur Stance and Gait and the Interpretation of Trackways

The tracks ascribed to pterosaurs from the Late Jurassic limestones at Crayssac, France, must be pterosaurian because the manus prints are so far outside those of the pes, the pes print is four times longer than wide, and the manus prints appear to preserve distinct traces of a posteromedially directed wing-finger. These tracks are different in important ways from previously described Pteraichnus trackways, which have been variably considered pterosaurian, crocodilian, or indeterminate. No Pteraichnus (sensu stricto: those not from Crayssac) tracks have diagnostic features of pterosaurs and in none can a complete phalangeal or digital formula be reconstructed; however, all published Pteraichnidae tracks fulfill the criteria of poor preservation, and some have some diagnostic features of crocodile tracks. Reconstructions of pterosaurs walking in pteraichnid tracks do not fit those tracks well, but crocodiles do. In contrast, the Crayssac tracks demonstrate the erect stance and parasagittal gait previously reconstructed for pterosaurs. They also demonstrate that the footfall pattern was not as in typical reptiles (LH-RF-RH-LF), but that the manus must have been raised before the next forward step of the ipselateral foot (LH-LF-RH-RF), suggesting that the quadrupedal pattern was secondary. The metatarsus in pterosaurs was set low at the beginning of a stride, as it is in crocodilians and basal dinosaurs. The diagnosis of the Ichnofamily Pteraichnidae comprises features of possible crocodilian trackmakers, but not of possible pterosaurian trackmakers. Trackways considered for attribution to pterosaurs should show (1) manus prints up to three interpedal widths from midline of body, and always lateral to pes prints, (2) pes prints four times longer than wide at the metatarso-phalangeal joint, and (3) penultimate phalanges longest among those of the pes.     

A case of chondrodystrophic dwarfism in the Italian late Upper Paleolithic

During excavations by P. Graziosi at Romito Cave near Papasidero (Cosenza) in Calabria, Italy, two skeletons (Romito 1 and 2) were discovered in a common grave. Although the specimens were briefly described by Messeri (Atti X Riuniuone Scientifica Ist. Ital. Preist. Protost., pp. 301-307, 1966), it is generally unknown in the anthropological literature that one of these individuals is a chondrodystrophic dwarf. As such, the specimen provides the earliest known case of dwarfism in the human skeletal record, extending the time span of this genetically determined growth abnormality to approximately 10,000 years ago. The specimen (Romito 2) exhibits features typical of chondrodysplasia, including a high domed skull, compressed cranial base, and in the postcranial skeleton extremely shortened diaphyseal lengths. The unique combination of these features suggests this pathological condition is acromesomelic dysplasia. Besides providing evidence for a greater antiquity of dwarfism than previously known, the fact that this individual reached late adolescence attests to tolerance of Upper Paleolithic groups for severely abnormal individuals and their ability to support members who were of limited economic value to the social group.     

Temnospondyl amphibians from the Jurassic of the Southern Junggar Basin (NW China)

For the first time, remains of post-Triassic temnosponyls are described from the southern Junggar Basin (NW China). Middle Jurassic material from the uppermost part of the Toutunhe Formation consists of several isolated but well preserved skull bones and intercentra from all regions of the body that can be attributed to a brachyopid. The material in part shares important autapomorphies withGobiops desertus Shishkin, 1991, from the Upper Jurassic of Outer Mongolia, and is consequently referred to this taxon, partially with reservation. This represents the first record of this genus from China. It also yields new anatomical data and permits an emended diagnosis.Ferganobatrachus from the Middle Jurassic of Kirghisia is probably, as also shown by the new material, congeneric withGobiops. Two fragmentary specimens from the lower part of the Upper Jurassic Qigu Formation are tentatively referred to the Brachyopoidea because of features of the skull, mandible and vertebral column. They probably both represent a single taxon that was larger and more massively built thanGobiops desertus but closely related to this form.      

Validation study of skull three-dimensional computerized tomography measurements

Recent advances in imaging have led to high-resolution computerized tomography (CT) scanning with exquisitely detailed slice images of the skull and three-dimensional (3-D) surface reconstructions using computer software. It is possible to use CT scans to acquire morphologic information about the skull in a convenient digital form and to derive 3-D measurements from surface reconstruction images. Unfortunately, no effort has been made to date to test the validity of these measurements on laboratory specimens, and no compelling evidence is available from phantom studies to indicate the nature and magnitude of the errors inherent in the measurement technique. We have performed a pilot study to quantify the morphology of the skull based on surface features that can be found in CT scans and 3-D reconstructions. Comparative measurements were obtained from five skulls (two normal and three with dysmorphology) with calipers and a 3-D electromagnetic digitizer. These measurements were statistically compared with those based on original CT scan slices and reformatted 3-D images. It is concluded that 3D-CT measurement techniques are superior to those in which measurements are obtained directly from the original CT slices; 3-D CT methods, however, must be significantly improved before measurements based on these techniques can be used in studies that require a high degree of precision. The results are used to indicate the most fruitful areas of future study.     

On a cranial bony nodular protuberance on Mourasuchus pattersoni Cidade et al. 2017 (Crocodylia,Alligatoroidea) from the late Miocene of Venezuela

Mourasuchus pattersoni, from the late Miocene Urumaco Formation of Venezuela, is the fourth and most recent species described for the genus. The holotype, and only known specimen, is comprised of an almost complete skull with both mandibular rami and several postcranial remains. In ventral view, the right palatine bone has a spherical, nodular bony protuberance located on the anterior portion, near the suture with the maxilla. Unfortunately, we cannot assign a specific diagnosis based only on macroscopic inspection. Its appearance, form and location are compatible with three conditions: torus palatinus, a common benign intraoral bone overgrowth; osteoma, a benign neoplasical overgrowth of the bone; and hamartoma, an overgrowth of normal bone tissue that can only be differed from an osteoma by histological features. While occurrences of torus palatinus or hamartomas are not yet known in the nonhominid vertebrate fossil record, there are previous records of osteomas in fossil vertebrates, including in crocodylians, such as a specimen assigned to ‘Crocodylus sp.’ from the Eocene, aside from several records for living crocodylians. Future studies are needed to uncover an accurate diagnosis of this unusual structure and help increase our knowledge of paleopathology in fossil crocodylomorphs in general, especially in the Caimaninae clade.