A new lizard-like reptile (Diapsida: Lepidosauromorpha) from the Middle Jurassic of England

The Middle Jurassic (Late Bathonian) Mammal Bed at Kirtlington, Oxfordshire, has yielded a rich assemblage of small vertebrates including mammals, frogs, salamanders and small reptiles. This paper describes the skull of a new diapsid reptile, Marmorelta oxoniensis, which was common within the fauna. The skull is gracile with large orbits and relatively long external nares. The frontals and parietals are single in the adult and almost separated on the roof of the skull by the postfrontals. The temporal region shows a mosaic of primitive and derived character states. The quadrate was firmly held to the skull by a large squamosal and a small, free, quadratojugal was retained. However, reduction of the anterior process of the quadratojugal and of the posterior process of the jugal left the lower temporal fenestra broadly open. Comparison with other diapsids leads to the conclusion that Marmoretta was a lepidosauromorph, most probably the sister taxon of Lepidosauria.     

Cranial anatomy of Shunosaurus, a basal sauropod dinosaur from the Middle Jurassic of China

Shunosaurus, from the Middle Jurassic of China, is probably the best‐known basal sauropod and is represented by several complete skeletons. It is unique among sauropods in having a small, bony club at the end of its tail. New skull material provides critical information about its anatomy, brain morphology, tooth replacement pattern, feeding habits and phylogenetic relationships. The skull is akinetic and monimostylic. The brain is relatively small, narrow and primitively designed. The tooth replacement pattern exhibits back to front replacement waves in alternating tooth position. The teeth are spatulate, stout and show well‐developed wear facets indicative of coarser plant food. Upper and lower tooth rows interdigitate and shear past each other. Tooth morphology, skull architecture, and neck posture indicate that Shunosaurus was adapted to ground feeding or low browsing. Shunosaurus exhibits the following cranial autapomorphies: emargination of the ventral margin of the jugal/quadratojugal bar behind the tooth row; postorbital contains a lateral pit; vomers do not participate in the formation of the choanae; pterygoid is extremely slender and small with a dorsal fossa; quadrate ramus of the pterygoid is forked; quadratojugal participates in the jaw articulation; tooth morphology is a combination of cylindrical and spatulate form; basipterygoid process is not wrapped by the caudal process of the pterygoid; trochlear nerve has two exits; occlusal level of the maxillary tooth row is convex downward, whereas that of the dentary is concave upward, acting like a pair of garden shears; dentary tooth count is 25 or more; and the replacing teeth invade the labial side of the functional teeth. Cranial characters among the basal sauropods are reviewed. As Shunosaurus is the earliest sauropod for which cranial remains are known, it occupies an important position phylogenetically, showing the modification of skull morphology from the prosauropod condition. Although the skull synapomorphies of Sauropoda are unknown at present, 27 cranial synapomorphies are known for the clade Eusauropoda. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136 , 145?169.     

The skull and the palaeoecological significance of Labidosaurus hamatus, a captorhinid reptile from the Lower Permian of Texas

The cranial skeleton of the large captorhinid reptile Labidosaurus hamatus , known only from the Lower Permian of Texas, is described on the basis of new, undescribed specimens. Labidosaurus is distinguished from other captorhinids by the more extreme sloping of the ventral (alveolar) margin of the premaxilla, a low dorsum sellae of the parabasisphenoid, a reduced prootic, a narrow stapes, and a relatively small foramen intermandibularis medius. Despite the presence of a single row of teeth in each jaw, the skull of Labidosaurus resembles most closely those of moradisaurines, the large multiple-tooth-rowed captorhinids of the latest Early and Middle Permian. A phylogenetic analysis confirms that the single-tooth-rowed L. hamatus is related most closely to moradisaurines within Captorhinidae, a relationship that supports the hypothesis of a diphyletic origin for multiple rows of marginal teeth in captorhinids (in the genus Captorhinus and in the clade Moradisaurinae). In view of the close relationship between L. hamatus and moradisaurines, which are regarded to have been herbivorous, L. hamatus is a critical taxon for studies of the evolution of herbivory in early tetrapods. L. hamatus shares several trademark features of herbivorous adaptation with moradisaurines, which suggest that this captorhinid species was omnivorous. As such, it represents a transitional taxon between faunivorous basal reptiles and the herbivorous moradisaurines.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 237–262.     

The cranial skeleton of the Early Permian aquatic reptile Mesosaurus tenuidens: implications for relationships and palaeobiology

The cranial osteology of the aquatic reptile Mesosaurus tenuidens is redescribed on the basis of new and previously examined materials from the Lower Permian of both southern Africa and South America. Mesosaurus is distinguished from other mesosaurs in exhibiting an absolutely larger skull and possessing relatively longer marginal teeth. The teeth gradually angle outwards as one progresses anteriorly in the tooth row and become conspicuously procumbent at the tip of the snout. The suggestion that mesosaurs used their conspicuous dental apparatus as a straining device for filter feeding is based upon erroneous reconstruction of a high number of teeth in this mesosaur. Reinterpretation of the morphology and the organization of the marginal teeth of Mesosaurus suggests that they were used to capture individually small, nektonic prey. General morphological aspects of the skull support the idea that Mesosaurus was an aquatic predator and that the skull was well adapted for feeding in an aqueous environment. The anatomical review permits critical reappraisal of several cranial characters that have appeared in recent phylogenetic analyses of early amniotes. Emendation of problematic characters and reanalysis of amniote phylogeny using a slightly modified data matrix from the literature strengthens the hypothesis that mesosaurs form a clade with millerettids, procolophonoids and pareiasaurs within Reptilia.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 345–368.     

Two new basal crocodylomorph archosaurs from the Lower Jurassic and the monophyly of the Sphenosuchia

We report on and name two new taxa of basal crocodylomorph archosaurs from the Lower Jurassic, Litargosuchus leptorhynchus gen. et sp. nov. , from the upper Elliot Formation (Stormberg Group) of South Africa, and Kayentasuchus walkeri gen. et sp. nov. , from the Kayenta Formation (Glen Canyon Group) of Arizona, USA. Examination of this material led to a reconsideration of basal crocodylomorph interrelationships. A phylogenetic analysis found no support for the monophyly of Sphenosuchia.  © 2002 The Linnean Society of London. Zoological Journal of the Linnean Society , 2002, 136 , 77–95.     

New data on the braincase of the aetosaurian archosaur (Reptilia: Diapsida) Stagonolepis robertsoni Agassiz

New data on the braincase of the aetosaurian archosaur Stagonolepis robertsoni Agassiz are presented, based on new preparation, synthetic casting, and interpretation of fossil material from the Triassic Elgin Sandstones, Scotland. The metotic fissure is not divided by bone. The perilymphatic foramen is completely bound by bone, and faces away from the otic capsule in a posterolateral direction. A prominent subvertical ridge on the anterolateral edge of the exoccipital and upper part of the basioccipital cannot be directly associated with the subcapsular process of the chondrocranium of extant crocodilians. This ridge projects laterally beyond the ventral ramus of the opisthotic, and lies anterior to the external foramina for the hypoglossal nerve. The overall structure of the braincases (especially the otic region) of S. robertsoni and other aetosaurians, where known, is more similar (in terms of derived archosaurian characters) to those of crocodylomorphs than are the braincases of other major suchian groups. This provides evidence for the currently unorthodox hypothesis that, among major suchian clades, Aetosauria and Crocodylomorpha are each others' closest relatives. Support for this hypothesis is found in features of the palatine and prefrontal that have not been considered in recent studies of suchian phylogeny. This alternative phylogenetic hypothesis demands further investigation but, combined with the new morphological data that it explains, it provides a framework for the understanding of the evolution of the derived and distinctive braincase structure of extant crocodilians.  © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136 , 7−23.     

Morphology and function of the head in foetal and juvenile Scolecomorphus kirkii (Amphibia: Gymnophiona: Scolecomorphidae)

The external and musculoskeletal morphology of the head is described for an ontogenetic series of the scolecomorphid caecilian Scolecomorphus kirkii . The rostral region of foetuses and juveniles is expanded into large, posterolaterally pointing paraoral processes that are formed by the maxilla. Extraoral teeth are present on the underside of the rostrum and laterally on the paraoral processes. In the foetuses, teeth are covered by epidermal tissue. The endoskeletal part of the foetal skull is largely cartilaginous, but all of the dermal bones, with the exception of the squamosal, are present. The foetal chondrocranium is extensively developed and shows a peculiar, posterolateral process of the nasal capsule that is connected to the trabecula cranii by a transverse bar posterior to the choana, and extends further posterior beyond the level of the posterior end of the pila antotica. Only two mm. adductor mandibulae are present, together with two pterygoideus muscles that insert onto the lower jaw. The palatoquadrate and quadrate of foetuses and juveniles, respectively, are highly mobile. It is suggested that the derived head morphology of Scolecomorphus foetuses and juveniles is an adaptation to specialized postparitive feeding.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 491–504.     

辽宁早白垩世义县组一原始鸟脚类恐龙

初步记述了采自辽西地区早白垩世义县组新的原始鸟脚类恐龙化石材料,并依此建立一新属新种上园热河龙（Jeholosaurus shangyuanensis gen. et sp. nov.）。化石产于北票市上园镇陆家屯义县组下部第一段灰白色凝灰质砂岩中,同一层位产出过大量鹦鹉嘴龙化石。上园热河龙的主要鉴定特征包括6个前上颌齿,鼻骨背面发育小孔,前齿骨约为前上颌骨主体长度的1.5倍、未发育股骨前髁间沟、骨不在一平面上,第三趾趾节中第四节最长。上园热河龙具有一些真鸟脚类恐龙的近裔性状,比如眶前孔小,方骨孔大,位于方颧骨侧面,外下颌孔缺失。另外,上园热河龙的股骨近端形态非常接近进步的鸟脚类恐龙。但是上园热河龙发育有6个前上颌齿,上下颌关节处与齿列位于同一水平线,前上颌齿列与上颌齿列位于同一水平线,这些原始特征未见于已知鸟脚类恐龙。上园热河龙确切系统分类位置需要进一步确定。 上园热河龙是义县组中发现的第二种鸟臀类恐龙,增加了这类恐龙在热河生物群中的分异度。     

Climatic change and body size in two species of Japanese rodents

Using museum specimens, we studied temporal changes in skull size in two species of Japanese rodents, the large Japanese field mouse ( Apodemus speciosus ) and Pratt's vole ( Eothenomys smithii  =  E. kageus ) during the 20th century. We used the greatest length of the skull (GTL), zygomatic breadth (ZB), narrowest width of the skull across the interorbital region (IC) and the length of the upper cheek teeth row (M) as indicators to such changes. We found that GTL and ZB (but not IC and M) increased during the study period in mice, and that IC and M (but not GTL and ZB) increased marginally in voles. We attribute these changes to elevated ambient minimal temperatures, which increased food availability and energy savings for the mice, and required diet change in the voles.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 263–267.     

Braincase evolution in suchian archosaurs (Reptilia: Diapsida): evidence from the rauisuchian Batrachotomus kupferzellensis

The osteology of an almost complete braincase of the rauisuchian archosaur Batrachotomus kupferzellensis Gower from the Middle Triassic of Germany is described. There is a possibly discrete epiotic ossification, the metotic fissure is undivided by bone (i.e. there is a metotic foramen), the medial wall of the otic capsule is mostly ossified, the cerebral branch of the internal carotid artery entered the lateral surface of the parabasisphenoid, the ventral ramus of the opisthotic is more prominent laterally than a strong subvertical ridge on the exoccipital and basioccipital that lies posterior to the external foramen for the hypoglossal nerve, and the perilymphatic foramen faces away from the otic capsule in a posterior direction. Braincase morphology in the rauisuchians Saurosuchus galilei , Postosuchus kirkpatricki, and Tikisuchus romeri is reviewed. A matrix of 27 braincase characters for 12 archosaurian taxa is analysed. The most parsimonious hypothesis is consistent with the currently orthodox view of archosaurian phylogeny, except in that aetosaurians are more closely related to crocodylomorphs than is any rauisuchian. This phylogeny is used in a brief interpretation of the evolution of derived braincase features present in extant crocodilians. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society , 2002, 136 , 49–76.     

A new stereospondyl from the German Middle Triassic, and the origin of the Metoposauridae

Recent finds of well-preserved temnospondyl skeletons from the Lower Keuper (Ladinian, Middle Triassic) in southern Germany are assigned to a new genus and species, Callistomordax kugleri . This taxon is characterized by the following autapomorphies: (1) wide unpaired frontal; (2) vomerine fangs greatly enlarged to occupy entire width of element; (3) intercentra elongated and massive, anterior face being convex; (4) humerus semilunar with enlarged deltopectoral crest; (5) cleithrum strongly curved and bow-shaped; (6) trunk extremely elongated to reach three times the length of the skull. Callistomordax shares with the Metoposauridae the pattern of dermal ornamentation, the proportion of both posterior skull table and snout, the position of the lacrimal, the morphology of the basicranial region, and the structure of the clavicle and interclavicle. Phylogenetic analysis suggests Callistomordax to be the sister taxon of the Metoposauridae, nested within a grade formed by various trematosaurian taxa. In this assemblage, Lyrocephaliscus and a clade formed by Almasaurus , Rileymillerus , Callistomordax , and the Metoposauridae are sister taxa. In all variants of the cladistic analysis, Callistomordax and the Metoposauridae form immediate sister groups. According to the present findings, neither plagiosaurids nor brachyopoids and rhytidosteids are closely related to this 'trematosaurian' monophylum, although these taxa share a range of homoplasies.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 79–113.     

Killer sperm whale: a new basal physeteroid (Mammalia, Cetacea) from the Late Miocene of Italy

Zygophyseter varolai , a new genus and species of Physeteroidea (Cetacea, Odontoceti), is based on an almost complete skeleton from the Late Miocene (Tortonian) in southern Italy. The extreme elongation of the zygomatic process of the squamosal and the circular supracranial basin (probably for housing the spermaceti organ) delimited by a peculiar anterior projection of the supraorbital process of the right maxilla are the most distinctive features of this bizarre sperm whale. Large body size, large teeth present in both lower and upper jaw, and anteroposteriorly elongated temporal fossa and zygomatic process of the squamosal indicate that this cetacean (for which we suggest the English common name killer sperm whale) was an active predator adapted to feeding on large prey, similarly to the extant killer whale ( Orcinus orca ). A phylogenetic analysis reveals that Zygophyseter belongs to a Middle–Late Miocene clade of basal physeteroids, together with Naganocetus (new genus for the type of ' Scaldicetus ' shigensis ). Moreover, the phylogenetic analysis shows evidence of a wide physeteroid radiation during the Miocene and that the extant Physeter and Kogia belong to two distinct families that form a clade representing the crown-group Physeteroidea.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 148 , 103–131.     

The skull of a large Lower Triassic ichthyosaur from Spitzbergen and its implications for the origin of the Ichthyosauria

An incomplete ichthyosaur skull from the Lower Triassic (Spathian) Sticky Keep Formation of Spitzbergen is one of the earliest ichthyosaurs known and by far the largest of the most basal ichthyosaurs. The specimen shows an extremely plesiomorphic cheek region of the skull and allows for the first time a confident reconstruction of the grundplan condition of the lower cheek region of ichthyosaurs. It unequivocally demonstrates the presence of a deep emargination of the lower cheek, which is bordered dorsally by the quadratojugal, squamosal and jugal, and therefore a plesiomorphic lack of contact between jugal and quadratojugal. The specimen also allows an evaluation of recent skull reconstructions of several Lower Triassic taxa which probably contain severe misinterpretations. The structure of the temporal and cheek region of the specimen can be most parsimoniously explained by the initial presence of a lower temporal fenestra. This provides important new evidence that the ancestry of ichthyosaurs might have lain within the Diapsida or their stem-group.