A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province,Northeastern Thailand

A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms.     

Fragilicetus velponi: a new mysticete genus and species and its implications for the origin of Balaenopteridae (Mammalia,Cetacea, Mysticeti)

A new extinct genus, F ragilicetus gen. nov. , is described here based on a partial skull of a baleen‐bearing whale from the Early Pliocene of the North Sea. Its type species is F ragilicetus velponi sp. nov. This new whale shows a mix of morphological characters that is intermediate between those of Eschrichtiidae and those of Balaenopteridae. A phylogenetic analysis supported this view and provided insights into some of the morphological transformations that occurred in the process leading to the origin of Balaenopteridae. Balaenopterid whales show specialized feeding behaviour that allows them to catch enormous amounts of prey. This behaviour is possible because of the presence of specialized anatomical features in the supraorbital process of the frontal, temporal fossa, glenoid fossa of the squamosal, and dentary. F ragilicetus velponi gen. et sp. nov. shares the shape of the supraorbital process of the frontal and significant details of the temporal fossa with Balaenopteridae but maintains an eschrichtiid‐ and cetotheriid‐like squamosal bulge and posteriorly protruded exoccipital. The character combination exhibited by this cetacean provides important information about the assembly of the specialized morphological features responsible for the highly efficient prey capture mechanics of Balaenopteridae. © 2015 The Linnean Society of London     

SKULL MORPHOLOGY AND PHYLOGENETIC RELATIONSHIPS OF A NEW DIMINUTIVE BALAENID FROM THE LOWER PLIOCENE OF BELGIUM

Abstract:  A new small balaenid is described and compared to all fossil and living balaenid taxa. The specimen represents a new genus and species and is named Balaenella brachyrhynus . It was discovered in the Lower Pliocene of Kallo (north-west Antwerp, Belgium) and adds new information on the diversity and evolution of Balaenidae. Based on both comparative morphology and phylogenetic analysis, Balaenella brachyrhynus is morphologically closer to the genus Balaena , including the living Greenland Bowhead whale ( B. mysticetus ), and two Pliocene species ( B. montalionis and B. ricei ) from central Italy and the eastern USA. Balaenella brachyrhynus has very short nasals, a short rostrum relative to the total skull length and a horizontal supraoccipital. A cladistic treatment of 81 morphological character states scored for 10 balaenids and nine non-balaenid cetaceans revealed that the other small balaenids generally included in the genus Balaenula (including Balaenula astensis, B. balaenopsis and a Pliocene Balaenula sp. from Japan) are closer to the living genus Eubalaena (the Right whale). As the new skull is so different from the nominal Balaenula species, and as it is more closely related to Balaena than to Eubalaena , it is concluded that a small body size was a common condition in different Balaenidae clades.     

记裂头鳄属(Dibothrosuchus)一新种

本文记述的裂头鳄属-新种 (Dibothrosuchus xingsuensis sp. nov.)的标本采自云南禄丰盆地下禄丰组深红层.通过描述,对裂头鳄属属级特征作了补充.新种的头骨中鳞骨缺失降突;方骨极度向前背方伸展,形成大的耳凹,乌喙骨具后腹突,以及具有鳄类式的腕骨等,表明裂头鳄属应改属为楔形鳄科 (Sphenosuchidae).根据该科各属的头骨中方骨与脑颅侧壁的连接关系,可以清楚地看到楔形鳄科在这局部解剖学上存在一连续的发展过程.在形态上,裂头鳄属和南非的 Sphenosuehus (典型属)最为相近.     

Evolution and development of the mammalian jaw joint: Making a novel structure

A jaw joint between the squamosal and dentary is a defining feature of mammals and is referred to as the temporomandibular joint (TMJ) in humans. Driven by changes in dentition and jaw musculature, this new joint evolved early in the mammalian ancestral lineage and permitted the transference of the ancestral jaw joint into the middle ear. The fossil record demonstrates the steps in the cynodont lineage that led to the acquisition of the TMJ, including the expansion of the dentary bone, formation of the coronoid process, and initial contact between the dentary and squamosal. From a developmental perspective, the components of the TMJ form through tissue interactions of muscle and skeletal elements, as well as through interaction between the jaw and the cranial base, with the signals involved in these interactions being both biomechanical and biochemical. In this review, we discuss the development of the TMJ in an evolutionary context. We describe the evolution of the TMJ in the fossil record and the development of the TMJ in embryonic development. We address the formation of key elements of the TMJ and how knowledge from developmental biology can inform our understanding of TMJ evolution.     

贵州上三叠统一新的海龙(爬行纲:双孔亚纲)

根据头骨和下颌建立了海龙一新属新种——短吻贫齿龙(Miodentosaurus brevis gen.et sp.nov.)。其正型标本是采自贵州三叠纪法郎组的一具骨架(台中自然科学博物馆标本编号NMNS-004727/F003960)。虽然头后骨胳还没有修理,但是几近完好的头骨和下颌显示出许多与众不同的特征,足以确定该标本代表了一新的海龙属种。短吻贫齿龙是个体较大的海龙,其全长超过4 m,头骨背部最长约为33 cm。吻直且极短是其最显著的特征之一。其他主要特征有:前颌骨沿前背中央有一隆嵴;上颌仅前颌骨有6枚圆锥形齿,无上颌骨齿;上颌骨沿前腹侧缘有一沟槽;下颌齿骨齿都集中在前端且至多不超过6枚。依据上述这些特征很易把短吻贫齿龙与其他已知海龙相区别。短吻贫齿龙头骨顶面松果孔大且很前位,头骨腭面的锄骨和翼骨均无齿,它的颈较长(至少可以辨认出13个颈椎)。这些特征显示短吻贫齿龙可能与包括中国安顺龙属(Anshunsaurus)在内的Askeptosauroidea超科有相近的系统关系。     

Skeletal development of the direct-developing caecilian <Emphasis Type="Italic">Gegeneophis ramaswamii</Emphasis> (Amphibia: Gymnophiona: Caeciliidae)

A few previous studies of skeletal and especially skull development in Gymnophiona often provided contradictory results. We studied the development of the skull and vertebral column of Gegeneophis ramaswamii, a direct-developing Indian caeciliid, based on 13 specimens. The chondrocranium forms at (Brauer in Zool Jahrb Anat 12:477-508,1899) stage 38. First dermal and perichondral ossifications occur at stage 40. The first dermal bones to form are the mentomeckelian, dentary, angular, vomer, and premaxillary. These are followed by the coronoid, palatine, pterygoid, maxillary, and the skull-roofing bones. The last occurring dermal ossifications are the parasphenoid and the squamosal. We present evidence for the occurrence of a lacrimal bone. No ectopterygoid, basioccipital, supraoccipital, pleurosphenoid, postorbital, or supratemporal elements were found. We assess the homology of the bones constituting the caecilian skull and discuss the above-mentioned terminologies. The phylogenetic implications of our findings are briefly discussed and we conclude that the evidence from developmental morphology is at present consistent with a monophyletic Lissamphibia of temnospondyl origin.     

Rhynchocephalians (Diapsida: Lepidosauria) from the Jurassic Kota Formation of India

Despite their rarity today, rhynchocephalians formed a diverse Early Mesozoic clade with a comparatively good fossil record. They had a Pangaean distribution in the Late Triassic and Early Jurassic, although the Gondwanan record remains more limited than the Laurasian one. We report here on new sphenodontian material from the Jurassic Kota Formation of peninsular India. Two taxa are represented, and both are attributed to new genera. One is a relatively derived sphenodontian with a premaxillary morphology similar to that of the Late Triassic/ Early Jurassic genus Clevosaurus. The other is somewhat more primitive in its morphology, although clearly a crown-group sphenodontian. In addition, three dentary fragments and a partial maxilla signal the presence of a primitive pleurodont lepidosauromorph similar to the basal rhynchocephalians Gephyrosaurus and Diphydonto-saurus from Britain.     

Anatomical study of the skull of amphisbaenian Diplometopon zarudnyi (Squamata,Amphisbaenia)

This study investigates the amphisbaenian species skull which includes cranium, lower jaw and hyoid apparatus. The medial dorsal bones comprise the premaxilla, nasal, frontal and parietal. The premaxilla carries a large medial tooth and two lateral ones. The nasals are paired bones and separated by longitudinal suture. Bones of circumorbital series are frontal, orbitosphenoid and maxilla. The occipital ring consists of basioccipital, supraoccipital and exooccipital. Supraoccipital and basioccipital are single bones while the exo-occipitals are paired. The bones of the palate comprise premaxilla, maxilla, septomaxilla, palatine, pterygoid, ectopterygoid, basisphenoid, parasphenoid, orbitosphenoid and laterosphenoid. Prevomer and pterygoid teeth are absent. Palatine represent by two separate bones. The temporal bones are clearly visible. The lower jaw consists of the dentary, articular, coronoid, supra-angular, angular and splenial. The hyoid apparatus is represented by a Y-shaped structure. The mandible is long and is suspended from the braincase via relatively short quadrate. There is an extensive contact between the long angular and the large triangular coronoid. Thus inter-mandibular joint is bridged completely by the angular and consequently, the lower jaws are relatively rigid and kinetic. The maxillae are suspended from the braincase largely by ligaments and muscles rather than through bony articulation. In conclusion, the skull shape affects feeding strategy in Diplometopon zarudnyi. The prey is ingested and transported via a rapid maxillary raking mechanism.     

Latimeria chalumnae and its pedigree

Synopsis Latimeria is the product of a long coelacanth lineage, usually viewed as having changed very little. In this paper a classification of better known coelacanth genera is proposed based on a cladistic computer analysis of 56 morphological characters. Biometrical data are then matched with the classification to explore the possibility of identifying subtle change. It is concluded that throughout coelacanth history there have been changes in the structure of the vertebral column involving an overall increase in the number of vertebral elements, and a consequent crowding of these elements within the abdominal region. These changes may be associated with increasing lobation of the second dorsal and anal fins. In the skull, parameters involving the intracranial joint have also changed in such a way that the anterior part of the skull has lengthened in relation to the posterior part and this may be associated with an increase in length of the basicranial muscle.Abbreviations in text figures Ang angular - a.o.r anterior opening of th rostral organ - Art articular - ba.cr.m basicranial muscle - Basi basisphenoid - Boc basioccipital - bpt.pr basipterygoid process - c.p.l cheek pit line - De dentary - Esc extrascapular - eth.sp etmosphenoid - f.e frontoethmoid - Fr frontal - Fr.d descending process of frontal - intr. j intracranial joint - io.s interorbital septum - sc jugal sensory canal - L.e lateral ethmoid - m.Cor modified coronoid - Mm memtomeckelian - m.ot.sc medial branch of otic canal - Op operculum - o.p.l oral pit line - ot,occ otico-occipital - Pa parietal - Pa.d descending process of parietal - Par parasphenoid - pa.s parietal shield - p.Cor principal coronoid - Po postorbital - Pop preoperculum - p.o.r posterior openings of the rostral organ - Pmx premaxilla, Pre-preorbital - Pro prootic - Pro.p posterior process of prootic - Rart retroarticular - Sc.o sclerotic ossicle - So supraorbital - Soc supraoccipital - Sop suboperculum - Sp spiracular - spl splenial - Sq squamosal - Stt supratemporal - Stt.com supratemporal commissure - Stt.d descending process of supratemporal - Par.a.w ascending wing of parasphenoid - Te tectal - X level of vagus exit     

陕北槽齿类新发现

本文记述了采自陕北府谷县三迭系和尚沟组上部的一槽齿类化石。根据骨髂形态特征认为属于古鳄亚目的原鳄科,与Chasmatosaurus和Elaphrosuchus相近,但上颌骨参与外鼻孔的构成及前上颌骨不呈喙嘴状等却显著不同。为此另建立一新属(Xilousuchus)。考虑其一些进步的构造、新属种的生存时代应稍晚于上述Chasmatosaurus和Elaphrosuchus。     

A NEW SEMLIKIICHTHYS FISH (TELEOSTEI, PERCIFORMES) FROM THE UPPER MIOCENE OF CHAD: FOSSIL RECORD AND PALAEOBIOGEOGRAPHICAL IMPLICATIONS

Abstract:  Semlikiichthys is a fossil genus of perciform fish from the Neogene continental deposits of Africa. Until now, it was known in Mio-Pliocene sites of the Great Lake Region and of the River Nile by a single species, S. rhachirhinchus . Here, we describe new Semlikiichthys material recovered from Central Africa (Upper Miocene of Toros-Menalla, western Djurab, Chad), and compare it to S. rhachirhinchus , which is the only known species of the genus, and also with Lates niloticus , which is the fish in African Neogene deposits that most closely resembles it. We attribute the Chadian material to Semlikiichthys darsao sp. nov., based on ten osteological characters of the neurocranium, the maxilla, the dentary and the first vertebra. Our comparative anatomical study also enables us to provide a revised diagnosis for the genus and to reconsider the taxonomic attribution of the fossils assigned to it. Furthermore, the fossil record of Semlikiichthys supports a connection between sub-basins of the Nilo-Sudanese region during the Miocene, and a disruption between the Great Lake and the Nile Basin on the one hand and the Chadian Basin on the other before 7 Ma.     

The Taxonomic and Evolutionary History of Fossil and Modern Balaenopteroid Mysticetes

Balaenopteroids (Balaenopteridae + Eschrichtiidae) are a diverse lineage of living mysticetes, with seven to ten species divided between three genera (Megaptera, Balaenoptera and Eschrichtius). Extant members of the Balaenopteridae (Balaenoptera and Megaptera) are characterized by their engulfment feeding behavior, which is associated with a number of unique cranial, mandibular, and soft anatomical characters. The Eschrichtiidae employ suction feeding, which is associated with arched rostra and short, coarse baleen. The recognition of these and other characters in fossil balaenopteroids, when viewed in a phylogenetic framework, provides a means for assessing the evolutionary history of this clade, including its origin and diversification. The earliest fossil balaenopterids include incomplete crania from the early late Miocene (7–10 Ma) of the North Pacific Ocean Basin. Our preliminary phylogenetic results indicate that the basal taxon, “Megaptera” miocaena should be reassigned to a new genus based on its possession of primitive and derived characters. The late late Miocene (5–7 Ma) balaenopterid record, except for Parabalaenoptera baulinensis and Balaenoptera siberi, is largely undescribed and consists of fossil specimens from the North and South Pacific and North Atlantic Ocean basins. The Pliocene record (2–5 Ma) is very diverse and consists of numerous named, but problematic, taxa from Italy and Belgium, as well as unnamed taxa from the North and South Pacific and eastern North Atlantic Ocean basins. For the most part Pliocene balaenopteroids represent extinct species and genera and reveal a greater degree of morphological diversity than at present. The Pleistocene record is very limited and, unfortunately, fails to document the evolutionary details leading to modern balaenopteroid species diversity. It is evident, however, that most extant species evolved during the Pleistocene. Morphological and molecular based phylogenies support two competing hypotheses concerning relationships within the Balaenopteroidea: (1) balaenopterids and eschrichtiids as sister taxa, and (2) eschrichtiids nested within a paraphyletic Balaenopteridae. The addition of fossil taxa (including a new Pliocene species preserving a mosaic of balaenopterid and eschrichtiid characters) in morphological and “total evidence” analyses, offers the potential to resolve the current controversy concerning the possible paraphyly of Balaenopteridae.     

新疆吐谷鲁群天山贫齿鳄的再研究

本文对杨钟健1973年记述的—原鳄类成员——天山贫齿鳄 (Edentosuchus tienshanensis) 进行了修订和补充描述,并依据头骨及脊椎的特征将原订的贫齿鳄科 Edentosuchidae 归人中鳄亚目.文中对这一鳄类的年龄及齿列的功能形态进行了初步的探讨.     

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.     

A New Species of Goniopholis from the Upper Jurassic of Portugal

The new goniopholidid crocodile Goniopholis baryglyphaeus sp. nov. from the Kimmeridgian of Guimarota/Leiria, Portugal is based on the oldest known relatively complete skeleton of Goniopholis from Europe and consists of a nearly complete skull together with a mandible and various postcranial remains. G. baryglyphaeus shows characters that hitherto have only been described for Goniopholis simus : a caudal expansion of the prefrontal that excludes the frontal from the medial margin of the orbit; and the loss of contact between the paroccipital process and the lateral surface of the squamosal and the quadrate, which exposes the cranioquadrate canal laterally. This new species can be distinguished from other European Goniopholis species by an articular facet placed ventral to the retroarticular process, and directed slightly medioventrally; a caudal margin of the mandible forming almost a right angle at its caudoventral corner; an almost square rostrolateral corner of the cranial table; a straight transverse suture between the parietal and the frontal with a median rostral process; a rostrally tapering wedge-like lacrimal, and a regular heavy skull-sculpturing. The new find of Goniopholis in Portugal shows that this genus was distributed in a larger area, and was present much earlier, than hitherto reported in south-western Europe.     

THE ORIGIN OF AFRO-ARABIAN 'DIDELPHIMORPH' MARSUPIALS

Abstract:  New specimens of Peratherium africanum from Early Oligocene deposits of the Fayum, Egypt, provide key information on the relationships of the species. These include the first maxilla to be found and two additional dentaries. The maxilla can be demonstrated to belong to the same species as the holotype dentary by study of the occlusal relationships of upper and lower molars. It can be shown by several synapomorphies that P. africanum is the sister species to European Bartonian–Rupelian Peratherium lavergnense . P. africanum therefore belongs to the 'didelphimorph' family Herpetotheriidae, not to the peradectimorph family Peradectidae. The genus Qatranitherium , previously erected for this species alone, is here synonymized with Peratherium . Comparison with 'didelphimorphian' taxa from early Paleogene deposits of South America suggests more remote relationships, indicating an origin for P. africanum by dispersal from Europe as originally envisaged. The more precise relationships deduced here help to constrain the time interval for dispersal to Afro-Arabia, probably during the earliest Oligocene sea-level low.     

The skull and jaw musculature as guides to the ancestry of salamanders

The fossil record provides no evidence supporting a unique common ancestry for frogs, salamanders and apodans. The ancestors of the modern orders may have diverged from one another as recently as 250 million years ago, or as long ago as 400 million years according to current theories of various authors. In order to evaluate the evolutionary patterns of the modern orders it is necessary to determine whether their last common ancestor was a rhipidistian fish, a very primitive amphibian, a labyrimhodom or a ‘lissamphibian’. The broad cranial similarities of frogs and salamanders, especially the dominance of the braincase as a supporting element, can be associated with the small size of the skull in their immediate ancestors. Hynobiids show the most primitive cranial pattern known among the living salamander families and “provide a model for determining the nature of the ancestors of the entire order. Features expected in ancestral salamanders include: (1) Emargination of the cheek; (2) Movable suspensorium formed by the quadrate, squamosal and pterygoid; (3) Occipital condyle posterior to jaw articulation; (4) Distinct prootic and opisthotic; (5) Absence ol otic notch; (6) Stapes forming a structural link between braincase and cheek. In the otic region, cheek and jaw suspension, the primitive salamander pattern (resembles most closely the microsaurs among known Paleozoic amphibians, and shows no significant features in common with either ancestral frogs or the majority of labyrinth odonts. The basic pattern of the adductor jaw musculature is consistent within both frogs and salamanders, but major differences are evident between the two groups. The dominance of the adductor mandibulae externus in salamanders can be associated with the open cheek in all members of that order, and the small size of this muscle in frogs can be associated with the large otic notch. The spread of different muscles over the otic capsule, the longus head ol the adductor mandibulae posterior in frogs and the superficial head of the adductor mandibulae internus in salamanders, indicates that fenestration of the skull posterodorsal to the orbit occurred separately in the ancestors of the two groups. Reconstruction of the probable pattern of the jaw musculature in Paleozoic amphibians indicates that frogs and salamanders might have evolved from a condition hypothesized for primitive labyrinthodonts, but the presence of a large otic notch in dissorophids suggests specialization toward the anuran, not the urodele condition. The presence of either an einarginated cheek or an embayment of the lateral surface of the dentary and the absence of an otic notch in microsaurs indicate a salamander-like distribution of die adductor jaw muscles. The ancestors of frogs and salamanders probably diverged from one another in the early Carboniferous, Frogs later evolved from small labyrinthodonts and salamanders from microsaurs. Features considered typical of lissamphibians evolved separately in the two groups in the late Permian andTriassic.