Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia

Atoposaurids are a group of small‐bodied, extinct crocodyliforms, regarded as an important component of Jurassic and Cretaceous Laurasian semi‐aquatic ecosystems. Despite the group being known for over 150 years, the taxonomic composition of Atoposauridae and its position within Crocodyliformes are unresolved. Uncertainty revolves around their placement within Neosuchia, in which they have been found to occupy a range of positions from the most basal neosuchian clade to more crownward eusuchians. This problem stems from a lack of adequate taxonomic treatment of specimens assigned to Atoposauridae, and key taxa such as Theriosuchus have become taxonomic ‘waste baskets’. Here, we incorporate all putative atoposaurid species into a new phylogenetic data matrix comprising 24 taxa scored for 329 characters. Many of our characters are heavily revised or novel to this study, and several ingroup taxa have never previously been included in a phylogenetic analysis. Parsimony and Bayesian approaches both recover Atoposauridae as a basal clade within Neosuchia, more stemward than coelognathosuchians, bernissartiids, and paralligatorids. Atoposauridae is a much more exclusive clade than previously recognized, comprising just three genera (Alligatorellus, Alligatorium, and Atoposaurus) that were restricted to the Late Jurassic of western Europe, and went extinct at the Jurassic/Cretaceous boundary. A putative Gondwanan atoposaurid (Brillanceausuchus) is recovered as a paralligatorid. Our results exclude both Montsecosuchus and Theriosuchus from Atoposauridae. Theriosuchus is polyphyletic, forming two groupings of advanced neosuchians. Theriosuchus (restricted to Theriosuchus pusillus, Theriosuchus guimarotae, and Theriosuchus grandinaris) spanned the Middle Jurassic to early Late Cretaceous, and is known from Eurasia and North Africa. Two Cretaceous species previously assigned to Theriosuchus (‘Theriosuchus’ ibericus and ‘Theriosuchus’ sympiestodon) are shown to be nested within Paralligatoridae, and we assign them to the new genus Sabresuchus. The revised phylogenetic placement of Theriosuchus has several implications for our understanding of eusuchian evolution. Firstly, the presence of fully pterygoidean choanae, previously regarded as a defining characteristic of Eusuchia, is not found in some basal members of Eusuchia. However, eusuchians can be distinguished from Theriosuchus and other basal neosuchians in that their choanae are posteriorly positioned, with an anterior margin medial to the posterior edge of the suborbital fenestra. This feature distinguishes eusuchians from Theriosuchus and more basal neosuchians. Secondly, our refined understanding of Theriosuchus implies that this taxon possessed only amphicoelous presacral vertebrae, and therefore fully developed vertebral procoely is likely to have evolved only once in Crocodylomorpha, on the lineage leading to Eusuchia. These and other findings presented herein will provide an important framework for understanding the neosuchian–eusuchian transition.     

Atoposaurid crocodyliforms from the Khorat Group of Thailand: first record of <Emphasis Type="Italic">Theriosuchus</Emphasis> from Southeast Asia

We describe a partial crocodilian skull from the Mesozoic non-marine sediments of the Khorat Plateau Sao Khua Formation (Berriasian-Barremian) in northeastern Thailand and assign it to Theriosuchus grandinaris sp. nov. An isolated dentary from the Phu Kradung Formation (latest Jurassic–Early Cretaceous) is also tentatively assigned to the genus Theriosuchus, and an isolated tooth from the Khok Kruat Formation (Aptian-Albian) may belong to this genus. The Thai fossils represent the first unambiguous evidence of presence of Theriosuchus outside Europe. Its occurrence in Thailand increases the known diversity of neosuchian crocodyliforms from Southeast Asia and suggests that Atoposauridae had a wide geographical distribution from the Late Jurassic to the Early Cretaceous.     

四川自贡晚侏罗世西蜀鳄一新种

记述了四川省自贡市汇东新区自贡市乳品厂发现的西蜀鳄一新种——周氏西蜀鳄(Hsisosuchus chowi sp.nov.)。新种区别于西蜀鳄已知种的特征是:鼻骨后部沿缝合线有一浅的纵凹,额骨的眶缘向上凸起成嵴,沿额骨缝合线也隆起成一微弱的纵嵴,上颞窝的内侧缘向上凸起呈明显的嵴,顶骨具一前中突,侧视颧骨腹缘呈明显的波曲状,眶后骨前侧角约90°,鳞骨后侧突特别拉长,向侧下后方伸展,使鳞骨侧缘明显向内侧弓曲,左右外枕骨的枕髁部分不相接,翼骨的腹中嵴源于翼骨主体部分,内鼻孔位置比较靠前。此外,齿骨外面和夹板骨腹面具有发达的沟和嵴状雕饰,夹板骨参与下颌联合的部分比较长,肩胛片异常扩展,乌喙骨远端宽于近端,肱骨头增厚并强烈向内侧扩展,三角肌嵴发达,桡侧腕骨具发达的尺骨突,尺侧腕骨远端宽于近端,6列荐前部腹部骨板和3列尾部腹部骨板,也可能是周氏西蜀鳄的衍生特征,但这些性状在大山铺西蜀鳄中情况不明,有待更多的材料来证实。杨钟健、周明镇(1953)在建立西蜀鳄属之初就已注意到西蜀鳄是一种特化的鳄类,认为西蜀鳄不仅将原始特征和进步特征混存于一身,而且还具有一些一般鳄类所没有的独特性质。以此为基础,他们建立了西蜀鳄科。目前西蜀鳄类动物发现并不多,仅有1属2种,即重庆西蜀鳄和大山铺西蜀鳄,而且材料不完整,特别是头后骨骼保存不理想。周氏西蜀鳄的发现不仅扩大了西蜀鳄类的分布范围,而且还增加了我们对这一特化鳄类的认识。     

Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria,Pterodactyloidea) from the Upper Jurassic of Bavaria,Germany: The Problem of Cryptic Pterosaur Taxa in Early Ontogeny

The taxonomy of the Late Jurassic pterodactyloid pterosaur Pterodactylus scolopaciceps Meyer, 1860 from the Solnhofen Limestone Formation of Bavaria, Germany is reviewed. Its nomenclatural history is long and complex, having been synonymised with both P. kochi (Wagner, 1837), and P. antiquus (Sömmerring, 1812). The majority of pterosaur species from the Solnhofen Limestone, including P. scolopaciceps are represented by juveniles. Consequently, specimens can appear remarkably similar due to juvenile characteristics detracting from taxonomic differences that are exaggerated in later ontogeny. Previous morphological and morphometric analyses have failed to separate species or even genera due to this problem, and as a result many species have been subsumed into a single taxon. A hypodigm for P. scolopaciceps, comprising of the holotype (BSP AS V 29 a/b) and material Broili referred to the taxon is described. P. scolopaciceps is found to be a valid taxon, but placement within Pterodactylus is inappropriate. Consequently, the new genus Aerodactylus is erected to accommodate it. Aerodactylus can be diagnosed on account of a unique suite of characters including jaws containing 16 teeth per-jaw, per-side, which are more sparsely distributed caudally and terminate rostral to the nasoantorbital fenestra; dorsal surface of the skull is subtly depressed rostral of the cranial table; rostrum very elongate (RI = ∼7), terminating in a point; orbits correspondingly low and elongate; elongate cervical vertebrae (approximately three times the length of their width); wing-metacarpal elongate, but still shorter than the ulna and first wing-phalanx; and pteroid approximately 65% of the total length of the ulna, straight and extremely thin (less than one third the width of the ulna). A cladistic analysis demonstrates that Aerodactylus is distinct from Pterodactylus, but close to Cycnorhamphus Seeley, 1870, Ardeadactylus Bennett, 2013a and Aurorazhdarcho Frey, Meyer and Tischlinger, 2011, consequently we erect the inclusive taxon Aurorazhdarchidae for their reception.     

Description of Caurinus tlagu,new species,from Prince of Wales Island,Alaska (Mecoptera,Boreidae, Caurininae)

A new species of the cryptic, minute, wingless, and enigmatic taxon Caurinus, and the second for the subfamily Caurininae,is described from Prince of Wales Island in the Alexander Archipelago, Alaska. It is distinguished from its only congener, Caurinus dectes Russell, 1979b, which occurs 1,059 km southeast in Oregon and Washington, based on external morphology and sequences of the mitochondrial gene cytochrome oxidase II. These two species are probably evolutionary relicts – the only known members of a clade dating to the Late Jurassic or older.     

A new aspidorhynchid fish (Teleostei: Aspidorhynchiformes) from the Upper Jurassic of Ettling,Solnhofen, Bavaria,Germany

A new species of Aspidorhynchidae is described for the first time from the Late Jurassic of Ettling, some 50 km E-SE of Solnhofen, Bavaria, Germany. This new material is attributed to a new species, Aspidorhynchus sanzenbacheri, and is diagnosed by the abbreviated premaxillae, the form and disposition of teeth in the predentary, and the number of principal rays in the caudal fin.     

A Review of Shamosuchus and Paralligator (Crocodyliformes,Neosuchia) from the Cretaceous of Asia

The crocodyliform Shamosuchus is known from numerous Late Cretaceous localities in southern and eastern Mongolia and fragmentary remains from Uzbekistan. Seven species of Shamosuchus have been named from six localities in Mongolia and three in Uzbekistan. Six species originally described as Paralligator were later referred to Shamosuchus. Only the type species, Shamosuchus djadochtaensis has been examined in detail. Many of the named species of Shamosuchus show striking similarity in size and cranial morphology but most are based on partial remains suggesting that the true species diversity is overestimated. A review of all species referred to Shamosuchus recognizes three valid taxa: Shamosuchus djadochtaensis, S. gradilifrons, and S. major. Shamosuchus sungaricus, S. borealis, and S. karakalpakensis are nomena dubia, whereas S. ancestralis, S. ulgicus, S. tersus, and S. ulanicus are junior subjective synonyms of S. gradilifrons. Phylogenetic analysis of 318 phenotypic characters recovers a Paralligatoridae clade consisting of Shamosuchus, Rugosuchus, Batrachomimus, Glen Rose Form, and Wannchampsus. Shamosuchus is non-monophyletic: S. djadochtaensis is near the base of Paralligatoridae whereas S. gradilifrons + S. major are the most deeply nested. The name Paralligator is resurrected for this clade. Rugosuchus and Batrachomimus are sister taxa to Paralligator. Paralligatoridae is closely related to Theriosuchus, hylaeochampsids and a speciose Allodaposuchus clade, which together are the sister group of Borealosuchus plus Crocodylia. These results support the presence of a diverse clade in eastern Asia and western North America throughout the Cretaceous with origins in the Late Jurassic.     

The last hadrosaurid dinosaurs of Europe: A new lambeosaurine from the Uppermost Cretaceous of Aren (Huesca, Spain)

A new hadrosaurid dinosaur, Arenysaurus ardevoli gen. et sp. nov., from the Late Maastrichtian of Aren (Huesca, South-central Pyrenees) is described on the basis of a partial, articulated skull, mandibular remains and postcranial elements, including vertebrae, girdle and limb bones. Arenysaurus is characterized by having a very prominent frontal dome; nearly vertical prequadratic (squamosal) and jugal (postorbital) processes, and deltopectoral crest of the humerus oriented anteriorly. Moreover, it possesses a unique combination of characters: short frontal (length/width approximately 0.5); midline ridge of parietal at level of the postorbital-squamosal bar; parietal excluded from the occiput; squamosal low above the cotyloid cavity. A phylogenetical analysis indicates that Arenysaurus is a rather basal member of Lambeosaurinae and the sister-taxon to Amurosaurus and the Corythosaurini-Parasaurolophini clade. The phylogenetic and biogeographical relationships of Arenysaurus and other lambeosaurines suggest a palaeogeographical connection between Asia and Europe during the Late Cretaceous.     

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.     

Additional data on Todites (Osmundaceae) from the Lower Jurassic—with special references to the paleogeographical and stratigraphical distributions in China

Additional material of Todites (Osmundaceae) from the Lower Jurassic Xiangshan Group in Jiangsu and Anhui Provinces, Eastern China is investigated. Five species of Todites are described based on collections (including sterile and fertile pinnae) from eight localities along the Yangtze River, including Todites denticulatus (Brongniart) Krasser, Todites cf. goeppertianus (Muenster) Krasser, Todites nanjingensis sp. nov., Todites princeps (Presl) Gothan and Todites sp. Material of T. denticulatus and T. nanjingensis sp. nov. contains further data of the fertile pinnae. The stratigraphical ranges and the geographical distribution of the genus Todites in China are discussed and reviewed. Available data show that Todites mostly occurs in the Late Triassic to Middle Jurassic of China. The genus was widely distributed in both the Northern and Southern Floristic Provinces of China, and especially abundant and diverse in the Southern Floristic Province.     

New Middle Jurassic record of fern genus Eboracia (Dicksoniaceae,Filicales) and its spatio-temporal distribution in China

As an important component of the Mesozoic flora, the extinct fern genus Eboracia Thomas (Dicksoniaceae, Filicales) is widely reported in China with diverse fossil records. New material of Eboracia lobifolia, represented by a nearly intactly preserved fossil frond, is described herein from the Middle Jurassic Haifanggou Formation in Beipiao of western Liaoning, Northeast China. The frond is lanceolate in gross outline, at least 38.0 cm long, and can be divided into the basal sterile part, the upper fertile part and a transitional part in between. The new discovery confirms for the first time that the frond of E. lobifolia is hemidimorphic rather than holodimorphic. Many in-situ spores were detached from the sori of the fertile pinnae, which are characterized by rounded-tetrahedral shape, smooth surface, distinct border, and a wide, long triradiate crack almost reaching the equator. Comparing with dispersed spores in the same horizon, these in-situ spores seem to be most similar to Cyathidites minor Couper in morphology. A spatio-temporal analysis of Eboracia in China shows that Eboracia with totally four species occurred in a time interval ranging from the Late Triassic to the Early Cretaceous in China, and mostly flourished in the Middle Jurassic; the genus was widely distributed in both the Northern and Southern Phytofloristic Provinces of China, particularly in southern China during the Late Triassic to Early Jurassic, while more abundant and diverse in northern China during the Middle Jurassic to Early Cretaceous.     

A Belonostomus tenuirostris (Actinopterygii: Aspidorhynchidae) from the Late Jurassic of Kelheim (southern Germany) preserved with its last meal

A Belonostomus tenuirostris (Agassiz, 1833) from Late Kimmeridgian (Late Jurassic) of Kelheim (Solnhofen area; Bavaria, southern Germany) that was preserved with three prey fishes in its digestive tract is described. Two of the prey fishes can be assigned to cf. Leptolepides (Orthogonikleithridae), whereas the third possibly represents a juvenile Caturus sp. (Caturidae). This is the first record of a Belonostomus with several prey animals, and the first evidence of a caturid predated by an aspidorhynchid.     

The first euthemistid damsel-dragonfly?from the Middle Jurassic of China (Odonata,Epiproctophora,?Isophlebioptera)

Sinoeuthemis daohugouensis gen. et sp. n. is the first record of the isophlebiopteran family Euthemistidae from Middle Jurassic of northeast China, while previously this family was restricted to the early Late Jurassic Kazakhstan. This new finding allows us to emend the family diagnosis with hindwing characters. This new species shows a mixture of characters alternatively present in different genera of the two families Euthemistidae and Sphenophlebiidae.     

Sexual dimorphism of craniological characters in Eurasian badgers, Meles spp. (Carnivora, Mustelidae)

An analysis of 30 craniological characters of Eurasian badgers (Meles spp.) revealed different levels of sexual size dimorphism (SSD) and geographic variation in the three different species. SSD is displayed mostly in the general size of the skull (condylobasal length, zygomatic width, width of rostrum, and cranial height) and mandible (height of the vertical mandibular ramus, total length of the mandible, and length between the angular process and infradentale), and in some dental characters (length of the upper molar M¹). The most stable size dimorphism is manifested in the size of the canines, which is pronounced in all studied samples. SSD is not apparent in the length of the auditory bulla, the postorbital width, the minimum palatal width, the length of the lower molar M₂, and the talonid length of the lower carnassial tooth M₁.In both the European badgers, Meles meles, and the Asian badgers, Meles leucurus, two geographic forms that differ in the degree of SSD have been found. The most pronounced SSD of cranial characters is found in the Transcaucasian form of Meles meles and the Far-Eastern form of Meles leucurus. In the large European form of Meles meles, SSD is less pronounced in both absolute and relative criteria than in the smaller Transcaucasian form. An analogous situation is observed in the larger Siberian and smaller Far-Eastern forms of Meles leucurus. In the Japanese badgers, Meles anakuma, a downsizing of the skull is accompanied by a decrease in SSD (except in canine size) in comparison to the continental species. The significant differences in the manifestation of SSD in the Eurasian badgers support an earlier hypothesis (Abramov, 2001. Proc. Zool. Inst. Russ. Acad. Sci. 288, 221-233; Abramov, 2002. Russ. J. Theriol. 1 (1), 57-60; Abramov, 2003. Small Carnivore Conserv. 29, 5-7) that Meles meles, Meles leucurus, and Meles anakuma are separate species. The differences in the level of SSD among and within these three species of badgers may be attributed not to differences in the diet or social structure, but to the history of speciation events and formation of intraspecific distribution ranges.     

The first find of chrysomelids (Insecta: Coleopetra: Chrysomeloidea) from Callovian-Oxfordian Daohugou biota of China

Tarsomegamerus mesozoicus nov. gen., nov. sp., an almost complete specimen of leaf beetle from the Callovian-Oxfordian of Daohugou Formation in Inner Mongolia, China is described. Tarsomegamerus mesozoicus is assigned to the Protoscelinae (Chrysomelidae, Coleoptera). This new leaf beetle represents the first record of chrysomeloids from Mesozoic of China and it extends the geographical distribution of Protoscelinae from central Asia into eastern Asia. This find provides new fossil material for studying the origin and evolution of Chrysomeloidea and by making a stratigraphic correlation of the correlative non-marine sedimentary rocks. Although the age of the Daohugou Formation is debatable it is most likely Callovian-Oxfordian (latest Middle Jurassic-earliest Late Jurassic) rather than early Middle Jurassic (late Aalenian-early Bajocian) or Early Cretaceous.     

Ophiuroid remains from the Toarcian of Sainte-Verge (Deux-Sèvres, France): paleobiological perspectives

The Toarcian sediments exposed at Sainte-Verge (Deux-Sèvres, France) are especially rich in echinoderm remains. The present paper describes and illustrates the ophiuroids. On the basis of lateral arm plates, 13 species are distinguished, including two new ones: Sinosura fasciata sp. nov. and Sinosura extensa sp. nov. Most of the recognized species have been recorded previously from the Late Toarcian and Aalenian in Germany and, to a lesser extent, from the late Early Jurassic of England and Switzerland. High similarities between the faunas of northwest Europe suggest a boreal provincialism of ophiuroids. The recognition of 13 species is comparable to the diversity known from other stratigraphic levels (Jurassic and Cretaceous) or in the richest stations of recent oceans. The species association of the Toarcian of Sainte-Verge, with two Ophiolepididae, one Ophiacanthidae, four Ophioleucidae, two Ophiodermatidae, two Ophiuridae, and one Hemieuryalidae may be compared with species associations of recent shelf, offshore environments. Such persistence of components of diversity and ecological affinities of species suggests strong evolutionary conservatism of the ophiuroids, after a rapid radiation during the earliest Jurassic. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.     

Two new species of Paramesosciophilodes (Diptera,Nematocera, Mesosciophilidae) from the Middle Jurassic of China

Two new species, Paramesosciophilodes bellus sp. n. and Paramesosciophilodes rarissima sp. n., from the Jiulongshan Formation at Daohugou Village, Inner Mongolia, China, are described in the extinct family Mesosciophilidae. Altogether seven genera with 21 species of mesosciophilids have been described from the Jurassic of Siberia and Kazakhstan, the Lower Cretaceous of Transbaikalia, and the Middle Jurassic of Inner Mongolia. An emended generic diagnosis of Paramesosciophilodes and a list of known taxa of mesosciophilids are provided.     

Miocene hyaenids (Hyaenidae; Carnivora) from Siwaliks of Pakistan

Newly discovered Miocene hyaenid specimens, recently collected from the Siwalik Group, are described and discussed. A careful comparison with the known material reveals that these specimens belong to the early hyaenid species Thalassictis cf. T. proava, Ictitherine indet. and Lepthyaena sivalensis. The stratigraphic range of T. proava extended up to the Dhok Pathan Formation (Middle Miocene to Early Pliocene). The stratigraphic range of T. proava comprises the Middle to Late Miocene, with the youngest record in Hasnot, Potwar Plateau in the Siwalik Group. The material is of great interest because Siwalik carnivoran material is rare.