Aerosteon riocoloradensis

Sereno, Martinez, Wilson, Varricchio, Alcober, and Larsson, 2008

Background
Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize) skeletal bone and thus leave a record of their presence.

Methodology/Principal Findings
We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal) that are involved in pulmonary ventilation. We also describe several pneumatized gastralia (“stomach ribs”), which suggest that diverticulae of the air sac system were present in surface tissues of the thorax.

Conclusions/Significance
We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds:

(1) Phase I—Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic.

(2) Phase II—Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac) and caudal (abdominal air sac) divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract with compliant air sacs, in turn, suggests the presence of rigid, dorsally attached lungs with flow-through ventilation.

(3) Phase III—Evolution of a primitive costosternal pump in maniraptoriform theropods before the close of the Jurassic.

(4) Phase IV—Evolution of an advanced costosternal pump in maniraptoran theropods before the close of the Jurassic.

In addition, we conclude:

(5) The advent of avian unidirectional lung ventilation is not possible to pinpoint, as osteological correlates have yet to be identified for uni- or bidirectional lung ventilation.

(6) The origin and evolution of avian air sacs may have been driven by one or more of the following three factors: flow-through lung ventilation, locomotory balance, and/or thermal regulation.

Phylogenetic position (provisional): Theropoda | Tetanurae | Carnosauria | Allosauroidea | Carcharodontosauridae

Picture credits: Todd Marshall, Nobu Tamura

Journal article: Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina (Direct to PDF)

Albertonykus borealis

Longrich and Currie, 2008

A new alvarezsaur, Albertonykus borealis, is described from the Lower Maastrichtian of the Horseshoe Canyon Formation, Alberta, Canada. Forelimb and hindlimb elements from at least two individuals were recovered from the Albertosaurus bonebed at Dry Island Provincial Park, along with pedal phalanges from nearby localities. Phylogenetic analysis shows that Albertonykus is the sister taxon of the Asian clade Mononykinae, consistent with the hypothesis that the alvarezsaurs originated in South America, and then dispersed to Asia via North America. The discovery of Albertonykus provides important insights into the biology of the Alvarezsauridae. As in other alvarezsaurs, the forelimbs of Albertonykus are specialized for digging, but they are too short to permit burrowing; they were most likely used to dig into insect nests. Potential prey items are evaluated in light of the fossil record of social insects. Ants were a minor part of the ecosystem during the Cretaceous, and mound-building termites do not appear untill the Eocene. This leaves the possibility that Albertonykus preyed on wood-nesting termites. We tested this hypothesis by examining silicified wood from the Horseshoe Canyon Formation. It was found that this wood frequently contains borings, which resemble the galleries of dampwood termites (Termopsidae).

Phylogenetic position (provisional): Theropoda | Tetanurae | Coelurosauria | Maniraptora | Alvarezsauridae

Picture credit: Todd Korol and Reuters

Nick Longrich's site: Albertonykus borealis

Anchiornis huxleyi

Xu X., Zhao, Q,, Norell, M., Sullivan, C., Hone, D., Erickson, G., Wang, X-L., Han, F-L., & Guo, Y. (2008)

Recent fossil discoveries have substantially reduced the morphological gap between non-avian and avian dinosaurs, yet avians including Archaeopteryx differ from non-avian theropods in their limb proportions. In particular, avians have proportionally longer and more robust forelimbs that are capable of supporting a large aerodynamic surface. Here we report on a new maniraptoran dinosaur, Anchiornis huxleyi gen. et sp. nov., based on a specimen collected from lacustrine deposits of uncertain age in western Liaoning, China. With an estimated mass of 110 grams, Anchiornis is the smallest known non-avian theropod dinosaur. It exhibits some wrist features indicative of high mobility, presaging the wing-folding mechanisms seen in more derived birds and suggesting rapid evolution of the carpus. Otherwise, Anchiornis is intermediate in general morphology between non-avian and avian dinosaurs, articularly with regard to relative forelimb length and thickness, and represents a transitional step toward the avian condition. In contrast with some recent comprehensive phylogenetic analyses, our phylogenetic analysis incorporates subtle morphological variations and recovers a conventional result supporting the monophyly of Avialae.

Journal article: A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin (Fee required)

Austroraptor cabazai

Novas, Pol, Canale, Porfiri, and Calvo, 2008

Fossils of a predatory dinosaur provide novel information about the evolution of unenlagiines, a poorly known group of dromaeosaurid theropods from Gondwana. The new dinosaur is the largest dromaeosaurid yet discovered in the Southern Hemisphere and depicts bizarre cranial and postcranial features. Its long and low snout bears numerous, small-sized conical teeth, a condition resembling spinosaurid theropods. Its short forearms depart from the characteristically long-armed condition of all dromaeosaurids and their close avian relatives. The new discovery amplifies the range of morphological disparity among unenlagiines, demonstrating that by the end of the Cretaceous this clade included large, short-armed forms alongside crow-sized, long-armed, possibly flying representatives. The new dinosaur is the youngest record of dromaeosaurids from Gondwana and represents a previously unrecognized lineage of large predators in Late Cretaceous dinosaur faunas mainly dominated by abelisaurid theropods.

Phylogenetic position (provisional): Theropoda | Tetanuranae | Coelurosauria | Maniraptora | Paraves | Dromaeosauridae | Unenlagiinea

Journal article: A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids (Direct to PDF)

Picture credit: Rodrigo Vega and Nobu Tamura

Camptosaurus aphanoecetes

Carpenter and Wilson, 2008

A new species, Camptosaurus aphanoecetes, is named for a partial skeleton of ornithopod dinosaur from the Morrison Formation (Upper Jurassic) of Dinosaur National Monument, Utah. The specimen was originally described as Camptosaurus medius Marsh, 1894, and later referred to Camptosaurus dispar (Marsh, 1879). Comparison of the specimen with a large sample of C. dispar from Quarry 13 shows differences in the proportions and shape of various axial and appendicular elements. Based on the dorsoventrally depressed form of the ilium, Camptosaurus depressus Gilmore, 1909 (Lower Cretaceous of South Dakota) is assigned to the Barremian genus Planicoxa DiCroce and Carpenter, 2001, as Planicoxa depressa, new combination. The well-preserved, undistorted forelimb material of C. aphanoecetes allows for a biomechanical analysis. The range of motion is rather limited throughout the forelimb. The analysis supports the quadrupedal locomotion previously hypothesized for Camptosaurus Marsh, 1885, from limb ratios, fusion of the wrist, and presence of short digits.

Phylogenetic position (provisional): 0rnithopod | Iguanodontia | Camptosauridae

Journal article: A new species of Camptosaurus (ornithopoda: dinosauria) from the morrison formation (upper jurassic) of dinosaur national monument, utah, and a biomechanical analysis of its forelimb (Direct to PDF)

Diceratus hatcheri

(Lull, 1905) comb. nov.

THE CERATOPSIAN dinosaur genera Diceratops Lull, 1905 and Microceratops Bohlin, 1953 are preoccupied by the Hymenoptera insects, Diceratops Foerster, 1868 and Microceratops Seyrig, 1952, respectively. Therefore, the name of the ceratopsian dinosaur Diceratops Lull, 1905 from the Late Cretaceous of United States is a junior homonym of the hymenoptera Diceratops Foerster, 1868. Diceratus n. gen. (Greek di = ‘‘two,’’ Greek ceratos = ‘‘horned’’) is proposed as the replacement name of Diceratops Lull, 1905. Some workers have considered Diceratops synonymous with Triceratops (e.g., Dodson and Currie, 1990) but it was reinstated by Forster (1996) after analysis of the characteristics of all existing ceratopsid skulls, and recent reviews (e.g., Dodson et al., 2004) have considered Diceratops a valid genus. Due to preoccupation, the name of the ceratopsian dinosaur Microceratops Bohlin, 1953 from the Cretaceous of the Gobi is a junior homonym of the insect Microceratops Seyrig, 1952. Microceratus n. gen. (Greek micro = ‘‘small,’’ Greek ceratos = ‘‘horned’’) is proposed as the replacing name of Microceratops Bohlin, 1953. Sereno (2000:489) has declared Microceratops a nomen dubium since the holotype material lacks any diagnostic features, a convention followed by You and Dodson (2004:480). However, the name is still used by Le Loeuff et al. (2002), Lucas (2006), Alifanov (2003) and Xu et al. (2002), and such practice justifies the renaming of the genus. In order to preserve some stability, the names chosen here deliberately preserve the same prefixes.

Phylogenetic position (provisional): Ceratopsia | Neoceratopsian | Ceratopsidae | Chasmosaurinae

Journal article: Two ornithischian dinosaurs renamed: Microceratops bohlin 1953 and Diceratops lull 1905 (Direct to PDF)

Picture credit: Nobu Tamura

Dongyangosaurus sinensis

Lu, Azuma, Chen, Zheng, and Ji, 2008

A new titanosauriform sauropod Dongyangosaurus sinensis gen. et sp. nov. from the early Late Cretaceous of Dongyang County, Zhejiang Province, is erected based on a partial postcranial skeleton. It is characterized by complex laminae on the lateral surface of the neural spines and postzygapophyses of dorsal vertebrae, a distinct fossa on the ventral surfaces of the prezygapophyses of dorsal vertebrae, distinct fossae are also present on the lateral surface of the postzygapophysis of anterior caudal vertebrae; pubis is shorter than ischium, the small obturator foramen of pubis elongated, and nearly closed. The lamina complexity of dorsal vertebrae in Dongyangosaurus indicates that a higher diversity of titanosauriformes occurred during the early Late Cretaceous in China.

Phylogenetic position (provisional): Sauropoda | Eusauropoda | Neosauropod | (non-titanosaurian Titanosauriforme)

Journal article: A New Titanosauriform Sauropod from the Early Late Cretaceous of Dongyang, Zhejiang Province (Fee required)

Picture credit: Acta Geologica Sinicia

Duriavenator hesperis

Waldman, 1974 comb. nov.

‘Megalosaurus’ hesperis from the Inferior Oolite (Bajocian, Middle Jurassic) of Dorset, UK is redescribed. Several features of ‘M.’ hesperis demonstrate that it is distinct from the lectotype dentary of Megalosaurus: an enlarged, subcircular third alveolus and subcylindrical, anteriorly inclined anterior dentary teeth; an anterior Meckelian foramen located almost directly anterior to the posterior Meckelian foramen; low interdental plates; and a prominent lip bounding the Meckelian groove ventrally, anterior to the Meckelian fossa. Therefore a new genus, Duriavenator, is erected to form the new combination D. hesperis. D. hesperis possesses two autapomorphies of the maxilla: a deep groove on dorsal surface of the jugal process containing numerous pneumatic foramina; and an array of small foramina in the ventral part of the articular surface for the premaxilla. Several features confirm the tetanuran affinities of D. hesperis: a prominent anterior process of the maxilla; the presence of band-like dental enamel wrinkles; the maxillary 'fenestra' is present but takes the form of an imperforate fossa (a spinosauroid synapomorphy); and the paradental groove is wide anteriorly, defining a distinct gap between the interdental plates and the medial wall of the dentary (a synapomorphy of Spinosauridae + Megalosauridae). Older records of tetanurans have been proposed, but most of these have been refuted and detailed re-examination of other early reports is warranted to establish the date of origin of this clade. An early Middle Jurassic origin of tetanurans is preferred.

Phylogenetic position (provisional): Theropoda | Tetanurae | Megalosauroidea | Megalosauridae

Journal article: A redescription of 'Megalosaurus' hesperis (Dinosauria, Theropoda) from the Inferior Oolite (Bajocian, Middle Jurassic) of Dorset, United Kingdom (Direct to PDF)

Eocarcharia dinops

Sereno and Brusatte, 2008

We report the discovery of basal abelisaurid and carcharodontosaurid theropods from the mid Cretaceous (Aptian-Albian, ca. 112 Ma) Elrhaz Formation of the Niger Republic. The abelisaurid, Kryptops palaios gen. et sp. nov., is represented by a single individual preserving the maxilla, pelvic girdle, vertebrae and ribs. Several features, including a maxilla textured externally by impressed vascular grooves and a narrow antorbital fossa, clearly place Kryptops palaios within Abelisauridae as its oldest known member. The carcharodontosaurid, Eocarcharia dinops gen. et sp. nov., is represented by several cranial bones and isolated teeth. Phylogenetic analysis places it as a basal carcharodontosaurid, similar to Acrocanthosaurus and less derived than Carcharodontosaurus and Giganotosaurus. The discovery of these taxa suggests that large body size and many of the derived cranial features of abelisaurids and carcharodontosaurids had already evolved by the mid Cretaceous. The presence of a close relative of the North American genus Acrocanthosaurus on Africa suggests that carcharodontosaurids had already achieved a trans-Tethyan distribution by the mid Cretaceous.

Phylogenetic position (provisional): Theropoda | Tetanurae | Carnosauria | Allosauroidea | Carcharodontosauridae

Journal article: Basal abelisaurid and carcharodontosaurid theropods from
the Lower Cretaceous Elrhaz Formation of Niger

Picture credit: Todd Marshall

Eomamenchisaurus yuanmouensis

Lu, Li, Zhong, Ji, and Li, 2008

A new mamenchisaurid dinosaur, Eomamenchisaurus yuanmouensis gen et sp. nov. is erected based on an incomplete skeleton from the Zhanghe Formation, the Middle Jurassic of Yuanmou, Yunnan Province. The new taxon is characterized by absence of pleurocoels in dorsal vertebrae and the dorsal verterbrae with slightly convex anterior articular surfaces, moderately concave posterior articular surfaces; the fourth trochanter is developed posteromedially on the femur; length ratio of the tibia to the femur is approximately 0.64; and the shaft of the ischium is rod-like. Two fused centra of the posterior dorsal vertebrae (the presumed 9th and the 10th dorsal vertebrae) are similar to those in other mamenchisaurid dinosaurs, including Mamenchisaurus hochuanesis, M. youngi and Chuanjiesaurus anaensis. Therefore, fusion of centra of the ninth and the tenth dorsal vertebrae can be recognized as a synapomorphic character of the Mamenchisauridae.

Phylogenetic position (provisional): Sauropoda | Eursauropoda | Euhelopodinae

Journal article: A New Mamenchisaurid Dinosaur from the Middle Jurassic of Yuanmou, Yunnan Province, China (Fee required)

Picture credit: Mitrchel Bogdanov (Mamenchisaurus)

Epidexipteryx hui

Zhang, Zhou, Xu, Wang, and Sullivan, 2008

Recent coelurosaurian discoveries have greatly enriched our knowledge of the transition from dinosaurs to birds, but all reported taxa close to this transition are from relatively well known coelurosaurian groups. Here we report a new basal avialan, Epidexipteryx hui gen. et sp. nov., from the Middle to Late Jurassic of Inner Mongolia, China. This new species is characterized by an unexpected combination of characters seen in several different theropod groups, particularly the Oviraptorosauria. Phylogenetic analysis shows it to be the sister taxon to Epidendrosaurus, forming a new clade at the base of Avialae. Epidexipteryx also possesses two pairs of elongate ribbon-like tail feathers, and its limbs lack contour feathers for flight. This finding shows that a member of the avialan lineage experimented with integumentary ornamentation as early as the Middle to Late Jurassic, and provides further evidence relating to this aspect of the transition from non-avian theropods to birds.

Phylogenetic position (provisional): Theropoda | Tetanuran | coelurosauria | maniraptora | Paraves | Scansoriopterygidae

Journal article: A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers (Fee required)

Picture credit: Zhao Chuang and Xing Lida, Nobu Tamura

Gobiceratops minutus

Alifanov, 2008

Phylogenetic position (provisional): Ceratopsian | Ceratopsidae | basal neoceratopsian

Picture credit: Nobu Tamura

Kryptops palaios

Sereno and Brusatte, 2008

We report the discovery of basal abelisaurid and carcharodontosaurid theropods from the mid Cretaceous (Aptian-Albian, ca. 112 Ma) Elrhaz Formation of the Niger Republic. The abelisaurid, Kryptops palaios gen. et sp. nov., is represented by a single individual preserving the maxilla, pelvic girdle, vertebrae and ribs. Several features, including a maxilla textured externally by impressed vascular grooves and a narrow antorbital fossa, clearly place Kryptops palaios within Abelisauridae as its oldest known member. The carcharodontosaurid, Eocarcharia dinops gen. et sp. nov., is represented by several cranial bones and isolated teeth. Phylogenetic analysis places it as a basal carcharodontosaurid, similar to Acrocanthosaurus and less derived than Carcharodontosaurus and Giganotosaurus. The discovery of these taxa suggests that large body size and many of the derived cranial features of abelisaurids and carcharodontosaurids had already evolved by the mid Cretaceous. The presence of a close relative of the North American genus Acrocanthosaurus on Africa suggests that carcharodontosaurids had already achieved a trans-Tethyan distribution by the mid Cretaceous.

Phylogenetic position (provisional): Theropoda | Ceratosauria | Abelisauridae

Journal article: Basal abelisaurid and carcharodontosaurid theropods from
the Lower Cretaceous Elrhaz Formation of Niger

Picture credit: Todd Marshall

Loricatosaurus priscus

Nopcsa, 1911 comb. nov.

Stegosauria is a clade of ornithischian dinosaurs characterised by a bizarre array of dermal armour extending, in two parasagittal rows, from the cervical region to the end of the tail. Although Stegosaurus is one of the most familiar of all dinosaurs, little is known regarding the evolutionary history of this clade. Alpha-level taxonomic revision of all proposed stegosaur taxa shows that 11 species of stegosaur can be regarded as valid on the basis of autapomorphies. These are: Dacentrurus armatus and Loricatosaurus priscus (gen. nov.) from Europe; Kentrosaurus aethiopicus and Paranthodon africanus from Africa; Tuojiangosaurus multispinus, Chungkingosaurus jiangbeiensis, Huayangosaurus taibaii, Gigantspinosaurus sichuanensis and Stegosaurus homheni (comb. nov.) from China; and Stegosaurus mjosi (comb. nov.) and Stegosaurus armatus from North America. A cladistic analysis of Stegosauria (the first to be based upon direct observation of all relevant specimens) is presented, which indicates that Tuojiangosaurus, Loricatosaurus and Paranthodon are sister taxa to Stegosaurus. Stegosaurinae can be defined as all stegosaurs more closely related to Stegosaurus than to Dacentrurus; Stegosauridae is defined as all stegosaurs more closely related to Stegosaurus than to Huayangosaurus; and Huayangosauridae can be defined as all stegosaurs more closely related to Huayangosaurus than to Stegosaurus. This study is also the first phylogenetic analysis to include Gigantspinosaurus, which is recovered as the most basal stegosaur.

Phylogenetic position (provisional): Thyreophora | Stegosauria | Stegosauridae

Journal article: Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia) (Fee required)

Malarguesaurus florenciae

González Riga, Previtera, and Pirrone, 2008

Malarguesaurus florenciae gen. et sp. nov. is a new and robust somphospondylian titanosauriform (Dinosauria, Sauropoda) from the Neuquén basin, Mendoza Province, Argentina. The specimen comes from Upper Cretaceous strata assigned to the Portezuelo Formation (upper Turonian-lower Coniacian). It includes proximal, middle and distal caudal vertebrae, chevrons, dorsal ribs, and appendicular bones. Malarguesaurus is characterized by the following association of characters: (1) proximal caudal neural spines vertically directed, with a concave caudal border, and a caudodorsal corner forming a right angle; (2) procoelous-opisthoplatyan proximal and middle caudal vertebrae associated with procoelous distal caudal centra; and (3) distal caudal neural spines having a concave and depressed dorsal border. A preliminary cladistic analysis placed (Ligabuesaurus + (Malarguesaurus + Phuwiangosaurus)) as a sister taxon of Titanosauria. Unique among the titanosauriforms, Malarguesaurus has procoelous distal caudal centra associated with procoelous-opisthoplatyan proximal caudals. This discovery is a new evidence of the morphologic diversity of the South American sauropods.

Phylogenetic position (provisional): Sauropoda | Eusauropoda | Neosauropod | (non-titanosaurian Titanosauriforme)

Journal article: Malarguesaurus florenciae gen. et sp. nov., a new titanosauriform (Dinosauria, Sauropoda) from the Upper Cretaceous of Mendoza, Argentina (Fee required)

Macrogryphosaurus gondwanicus

Calvo, Porfiri and Novas, 2008

We describe the postcranial skeleton of a new Cretaceous ornithopod, Macrogryphosaurus gondwanicus gen. nov., sp.nov. from Patagonia, Argentina. The specimen was found in the Portezuelo Formation, Neuquén Group, Upper Cretaceous. Macrogryphosaurus gondwanicus gen.nov., sp.nov. is diagnosed by having triradiate sternum with the anterior border tribranched, two laterally placed and outwardly directed, and one centrally placed, smaller, and forwardly directed. Sternal ribs flattened, twisted and distally expanded. Last dorsal vertebra with well-developed hyposphene. A thin plate-like are located in front of the sterna. Together with these autapomorphies, this new species of ornithopod differs from Talenkauen santacrucensis by having the pubic peduncle of ilium less developed, a more acute angle between the anterior process of ilium and the pubic peduncle, the acetabular cavity slightly marked. Also present ten cervical vertebrae, fourteen dorsal vertebrae, epipophyses on the third cervical vertebra placed over the distal end of the postzygapophyses and posteriorly projected. The presence of plates on the lateral side of the thorax and well developed epipophyses on the third cervical vertebra, were originally interpreted as autapomorphies for the euiguanodontian Talenkauen santacrucensis. These features are also present in Macrogryphosaurus gondwanicus gen.nov, sp.nov., and are regarded as synapomorphies defining a new clade of Euiguanodontia dinosaurs comprising the two species: Elasmaria nov.

Phylogenetic position (provisional): Ornithopoda | Iguanodontia | Elasmaria

Journal article: Discovery of a new ornithopod dinosaur from the Portezuelo Formation (Upper Cretaceous), Neuquén, Patagonia, Argentina (Direct to PDF)

Picture credit: EmperorDinobot (deviantART alias)

Microceratus gobiensis

Bohlin, 1953 comb. nov.

THE CERATOPSIAN dinosaur genera Diceratops Lull, 1905 and Microceratops Bohlin, 1953 are preoccupied by the Hymenoptera insects, Diceratops Foerster, 1868 and Microceratops Seyrig, 1952, respectively. Therefore, the name of the ceratopsian dinosaur Diceratops Lull, 1905 from the Late Cretaceous of United States is a junior homonym of the hymenoptera Diceratops Foerster, 1868. Diceratus n. gen. (Greek di = ‘‘two,’’ Greek ceratos = ‘‘horned’’) is proposed as the replacement name of Diceratops Lull, 1905. Some workers have considered Diceratops synonymous with Triceratops (e.g., Dodson and Currie, 1990) but it was reinstated by Forster (1996) after analysis of the characteristics of all existing ceratopsid skulls, and recent reviews (e.g., Dodson et al., 2004) have considered Diceratops a valid genus. Due to preoccupation, the name of the ceratopsian dinosaur Microceratops Bohlin, 1953 from the Cretaceous of the Gobi is a junior homonym of the insect Microceratops Seyrig, 1952. Microceratus n. gen. (Greek micro = ‘‘small,’’ Greek ceratos = ‘‘horned’’) is proposed as the replacing name of Microceratops Bohlin, 1953. Sereno (2000:489) has declared Microceratops a nomen dubium since the holotype material lacks any diagnostic features, a convention followed by You and Dodson (2004:480). However, the name is still used by Le Loeuff et al. (2002), Lucas (2006), Alifanov (2003) and Xu et al. (2002), and such practice justifies the renaming of the genus. In order to preserve some stability, the names chosen here deliberately preserve the same prefixes.

Journal article: Two ornithischian dinosaurs renamed: Microceratops bohlin 1953 and Diceratops lull 1905 (Direct to PDF)

Picture credit: Nobu Tamura

Muyelensaurus pecheni

Coria, Gonzalez-Riga and Porfiri, 2008

The discovery of Muyelensaurus pecheni gen. et sp.nov., a new slender titanosaurid, is relevant from anatomical and systematic viewpoints. The specimens come from the Upper Cretaceous strata of the Portezuelo Formation (Turonian-Early Coniacian) at Loma del Lindero, Rincón de los Sauces area, Neuquén Province, Argentina. The remains include a braincase, cervical, dorsal, sacral and caudal vertebrae, and numerous appendicular bones. It is characterized by the following association of autapomorphies: basal tubera diverge 70 degrees from each other; thin and concave lamina that unit basal tubera ventrally, basioccipital condyle wider than the proximal portion of the basal tubera; posterior dorsal neural spines with large prespinal lamina reinforced by two small accessory laminae, distal end of pubic blade rectangular and medially thick. A cladistic phylogenetic analysis placed Muyelensaurus pecheni gen. et sp.nov. and Rinconsaurus caudamirus in a new eutitanosaur clade named herein Rinconsauria. This new clade include middle-sized sauropods different from Aeolosaurini, Opisthocoelicaudiinae or Saltasaurinae taxa.

Phylogenetic position (provisional): Sauropoda | Eusauropoda | Neosauropoda | Titanosauria | Lithostrotia

Journal article: A new titanosaur sauropod from the Late Cretaceous of Neuquén, Patagonia, Argentina

Orkoraptor burkei

Novas, Ezcurra, and Lecuona, 2008

A new large theropod, Orkoraptor burkei nov. gen. et nov. sp., from the Upper Cretaceous (Maastrichtian) Pari Aike Formation of southern Patagonia is based on a postorbital, quadratojugal, coronoid?, several teeth, an atlantal intercentrum and neurapophysis, two caudal vertebrae, and the proximal half of tibia. This new theropod exhibits characteristics of maniraptorans (i.e., coelurosaurians more derived than tyrannosaurids) including an upturned rostral process of the postorbital, the caudoventral corner of which is widely concave. Furthermore, teeth without denticles and carina in the mesial margin resemble the condition of the maniraptoran clades Compsognathidae and Deinonychosauria. The new Patagonian theropod differs from other coelurosaurians (Ornithomimosauria, Compsognathidae, Alvarezsauridae, Dromaeosauridae, Aves) in having caudal vertebrae with a single pair of small pleurocoels on each side, and in having a median depression flanked by two longitudinal and narrow furrows on each tooth. Orkoraptor represents one of the southernmost carnivorous dinosaurs yet found in South America and adds valuable information about the diversification of tetanuran theropods in Gondwana.

Phylogenetic position (provisional): Theropoda | Tetanurae (incertae sedis)

Journal article: Orkoraptor burkei nov. gen. et sp., a large theropod from the Maastrichtian Pari Aike Formation, Southern Patagonia, Argentina (Fee required)

Pachyrhinosaurus lakustai

Currie, Langston, and Tanke, 2008

This new species of Pachyrhinosaurus is closely related to Pachyrhinosaurus canadensis, which is known from younger rocks near Drumheller and Lethbridge in southern Alberta, but is a smaller animal with many differences in the ornamental spikes and bumps on the skull. The adults of both species have massive bosses of bone in the positions where other horned dinosaurs (like Centrosaurus and Triceratops) have horns. However, juveniles of the new species resemble juveniles of Centrosaurus in having horns rather than bosses. Skull anatomy undergoes remarkable changes during growth and the horns over the nose and eyes of the Pachyrhinosaurus juveniles transform into bosses; spikes and horns develop on the top of and at the back of the frill that extends back over the neck. No cause has been determined for the apparent catastrophic death of the herd of Pachyrhinosaurus from the Grande Prairie area, but it has been suggested that such herds may have been migratory animals.

Phylogenetic position (provisional): Ceratopsia | Neoceratopsia | Ceratopsidea | Centrosaurinae

Monograph information: A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta

Picture credit: Nobu Tamura

Peloroplites cedrimontanus

Carpenter, Bird, Bartlett, and Barrick, 2008

A new large nodosaurid ankylosaur, Peloroplites cedrimontanus, is described from a partial skull and postcranial skeleton found at the PR-2 Quarry located at the base of the Mussentuchit Member of the Cedar Mountain Formation in central Utah. The specimen is about the same size as the contemporary nodosaurid Sauropelta edwardsorum from the Cloverly Formation of Montana, and is of an individual approximately 5–5.5 m long. The skull of Peloroplites differs from that of Sauropelta in the vertical orientation of the suspensorium, non-domed cranium and broad, square premaxillary beak. The quarry is near and roughly at the same level as the CEM Quarry that produced the holotype of the ankylosaurid Cedarpelta bilbeyhallorum. The postcrania of Cedarpelta is described and illustrated based on the paratype and new material. These elements clearly establish that Cedarpelta is closer to Ankylosaurus than to Sauropelta. As a primitive ankylosaurid, there is no a priori reason to assume that the tail club was present. Based on recent finds in China, a hypothesis is presented that the tail club is a derived feature in non-shamosaurine (i.e., ankylosaurine) ankylosaurids.

Phylogenetic position (provisional):
Thyreophora | Ankylosauria | Nodosauridae

Journal article: Ankylosaurs from the Price River Quarries, Cedar Mountain Formation (Lower Cretaceous), East-Central Utah (Fee required

Qingxuisaurus youjiangensis

Mo, Huang, Zhao, Wang, and Xu, 2008

Phylogenetic position (provisional): Sauropoda | Eusauropoda | Neosauropoda | Titanosauria | Lithostrotia | Saltasauridae

Pitekunsaurus macayai

Filippi and Garrido, 2008

A new titanosaur is described, Pitekunsaurus macayai gen. et sp. nov., from mudstone levels asigned to Anacleto Formation (Lower - Middle Campanian), corresponding to the uppermost beds of the Neuquen Group (Upper Cretaceous of Neuquen Basin). The specimen is represented by braincase, left frontal, one tooth, four cervical vertebrae, three dorsal vertebrae, four caudal vertebrae, right ulna and scapula, proximal extreme of left femur, rib fragments and uncertain remains. Pitekunsaurus is characterized by the following autapomorphies: (1) basipterygoid processes broadly separated and parallelly projected, (2) anterior cervical vertebrae with small depressions or longitudinal grooves in the spinal sector of spinopostzygapophyseal lamina, (3) centropostzygapophyseal lamina forked proximally in anterior dorsal vertebrae, and (4) posterior centrodiapophyseal lamina with accessory lamina in anterior dorsal vertebrae. The existence of two types of articulations in the posterior caudal vertebrae, one amphicoelous and another biconvex, indicates a close relationship with Rinconsaurus caudamirus Calvo Gonzalez Riga, suggesting that the caudal morphology of titanosaurs is much more complex and more varied than previously supposed.

Phylogenetic position (provisional): Sauropoda | Eusauropoda | Neosauropoda | Titanosauria | Lithostrotia

Sahaliyania elunchunorum

Godefroit, Hai, Yu, and Lauters, 2008

Several hundred disarticulated dinosaur bones have been recovered from a large quarry at Wulaga (Heilongjiang Province, China), in the Upper Cretaceous (Maastrichtian) Yuliangze Formation. The Wulaga quarry can be regarded as a monodominant bonebed: more than 80% of the bones belong to a new lambeosaurine hadrosaurid, Sahaliyania elunchunorum gen. et sp. nov. This taxon is characterised by long and slender paroccipital processes, a prominent lateral depression on the dorsal surface of the frontal, a quadratojugal notch that is displaced ventrally on the quadrate, and a prepubic blade that is asymmetrically expanded, with an important emphasis to the dorsal side. Phylogenetic analysis shows that Sahaliyania is a derived lambeosaurine that forms a monophyletic group with the corythosaur and parasauroloph clades. Nevertheless, the exact position of Sahaliyania within this clade cannot be resolved on the basis of the available material. Besides Sahaliyania, other isolated bones display a typical hadrosaurine morphology and are referred to Wulagasaurus dongi gen. et sp. nov., a new taxon characterised by the maxilla pierced by a single foramen below the jugal process, a very slender dentary not pierced by foramina, and by the deltopectoral crest (on the humerus) oriented cranially. Phylogenetic analysis indicates that Wulagasaurus is the most basal hadrosaurine known to date. Phylogeographic data suggests that the hadrosaurines, and thus all hadrosaurids, are of Asian origin, which implies a relatively long ghost lineage of approximately 13 million years for basal hadrosaurines in Asia.

Phylogenetic position (provisional): Ornithopoda | Iguanodontia | Hadrosauroidea | Hadrosauridae | Lambeosaurinae

Journal article: New hadrosaurid dinosaurs from the uppermost Cretaceous of northeastern China

Similicaudipteryx yixianensis

He, Wang, and Zhou, 2008
A new oviraptorosaur Similicaudipteryx yixianensis gen. et. sp. nov. is described from the Jiufotang Formation (120 Ma) of the Jehol Group in western Liaonong, China, which is referred to the Caudipteridae based on an dagger-like pygostyle and the shape of the ilium that are most similar to those of Caudipteryx. It differs from other oviraptorosaurids in that the ratio of pubis to ilium length is 1.46 and the presence of two large and deep hypapophyses on dorsal vertebrae. The known caudipterids have previously been found only from the Jianshangou Member of the Yixian Formation (125 Ma) of the Sihetun area in Liaoning Province. S. yixianensis represents the first caudipterid dinosaur from the Jiufotang Formation. The new discovery provides more information for the discussion of the evolution of oviraptorids during the Early Cretaceous and adds to the dinosaur assemblage of the Jehol Biota.

Phylogenetic position (provisional): Theropoda | Tetanurae | Coelurosauria | Maniraptora | Oviraptorosauria | Caudipterygidae

Skorpiovenator bustingorryi

Canale, Scanferla, Agnolin, and Novas, 2008

A nearly complete skeleton of the new abelisaurid Skorpiovenator bustingorryi is reported here. The holotype was found in Late Cenomanian–Early Turonian outcrops of NW Patagonia, Argentina. This new taxon is deeply nested within a new clade of South American abelisaurids, named Brachyrostra. Within brachyrostrans, the skull shortening and hyperossification of the skull roof appear to be correlated with a progressive enclosure of the orbit, a set of features possibly related to shock-absorbing capabilities. Moreover, the development of horn-like structures and differential cranial thickening appear to be convergently acquired within Abelisauridae. Based on the similarities between Skorpiovenator and carcharodontosaurid tooth morphology, we suggest that isolated teeth originally referred as post-Cenomanian Carcharodontosauridae most probably belong to abelisaurids.

Phylogenetic position (provisional): Theropoda | Ceratosauria | Abelisauridae | Carnotaurinae

Journal article: New carnivorous dinosaur from the Late Cretaceous of NW
Patagonia and the evolution of abelisaurid theropods (Direct to PDF)

Picture credit: Matt Celeskey

Stokesosaurus langhami

Benson, 2008

A partial postcranial skeleton from the Late Jurassic (Tithonian) of Dorset, England represents a new species of the theropod dinosaur Stokesosaurus, Stokesosaurus langhami. S. langhami is a member of Tyrannosauroidea, showing a distinct median vertical ridge on the lateral surface of the ilium, a prominent shelf medial to the preacetabular notch, a pronounced ischial tubercle, and a tibia that is elongate relative to the femur. One of only two definitive Jurassic tyrannosauroids known from more than isolated elements, it is the largest Jurassic tyrannosauroid reported to date and provides additional evidence for the presence of relatively small- or medium-sized basal tyrannosauroids in Asia, North America, and Europe during the Late Jurassic. The occurrence of Stokesosaurus in the Tithonian of the UK and USA and the absence of tyrannosauroids in contemporaneous west African faunas supports the hypothesis of a paleobiogeographic link during the Late Jurassic between North America and Europe, to the exclusion of Africa.

Phylogenetic position (provisional):
Theropoda | Tetanurae | Coelurosauria | Tyrannosauroidea (basal)

Journal article: New Information on Stokesosaurus, A Tyrannosauroid (Dinosauria: Theropoda) from North America and the United Kingdom

Picture credit: Todd Marshall, Nobu Tamura

Tastavinsaurus sanzi

Canudo, Royo-Torres, and Cuenca, 2008

The new sauropod dinosaur Tastavinsaurus sanzi, gen. et sp. nov., from the early Aptian of Spain is described. The holotype is a partially articulated skeleton of an adult individual recovered from the Arsis-1 site in Peñarroya de Tastavins (Teruel) at the base of the marine Xert Formation. It is one of the most complete and bestpreserved sauropod dinosaur skeletons from the European Early Cretaceous. The fossil remains comprise the three caudalmost thoracic vertebrae, part of a fourth, nine thoracic rib fragments, sacrum, 25 caudal vertebrae, 21 chevrons, both ilia, pubes, ischia and femora, right tibia, right fibula, six metatarsals, and seven pedal phalanges (including four unguals). The new taxon is defined by 19 autapomorphies. In our cladistic analysis, Tastavinsaurus is the sister-taxon of the North American Venenosaurus within Titanosauriformes, which includes the Brachiosauridae, Somphospondyli, and Titanosauria. The new taxon provides new information about the diversity of non-brachiosaurid titanosauriforms during the Early Cretaceous in Europe and paleobiogeographic relationships between Europe and North America.

Phylogenetic position (provisional): Sauropoda | Eusauropod | Neosauropoda | Titanosauriforme

Journal article: A New Sauropod: Tastavinsaurus sanzi Gen. Et Sp. Nov. from the Early Cretaceous (Aptian) of Spain

Picture credit: Francisco Gascó Lluna, Nobu Tamura

Uberabatitan ribeiroi

Salgado and Carvalho, 2008

A new Late Cretaceous titanosaur sauropod from the Bauru Basin of Brazil, Uberabatitan ribeiroi gen. et sp. nov., represented by at least three specimens, is described. The material comes from a level of coarse sandstone within the Serra da Galga sequence in Uberaba County, Minas Gerais State. The fossiliferous strata belong to the Marília Formation (Serra da Galga Member), Bauru Group, considered to be Maastrichtian in age. The fossils occur in the uppermost levels of the above-mentioned unit; thus, Uberabatitan ribeiroi is the youngest titanosaur to have been recorded from the Bauru Basin. The autapomorphies that support the new species are: (1) anterior and mid-cervicals with postzygodiapophyseal lamina (podl) segmented in zygapophyseal and diapophyseal laminae, of which the first extends rostrodorsally over the second; (2) mid-dorsals with a robust lateral lamina formed mainly by a diapophyseal lamina (probably homologous to the postzygodiapophyseal lamina), and, to a lesser extent, by a relic of the spinodiapophyseal lamina (spdl); (3) mid (and probably posterior) dorsals with accessory neural laminae, which are lateral to the prespinal lamina, and probably homologous to the spinoprezygapophyseal laminae (sprl); (4) mid-caudal centra with deeply excavated lateral faces; (5) pubis very thick and robust, with a very stout longitudinal crest on its external (ventral) face; and (6) proximal end of the tibia with a prominent lateral protuberance, which articulates with an equally prominent medial knob of the fibula. The titanosaurian assemblage at Uberaba includes, apart from U. ribeiroi, well-preserved specimens assigned to species of uncertain affinities (Trigonosaurus pricei and Baurutitan britoi), as well as a few vertebrae assigned to aeolosaurines.

Phylogenetic position (provisional):
Sauropoda | Eusauropoda | Neosauropoda | Titanosauria | Lithostrotia

Journal article: Uberabatitan ribeiroi, a new titanosaur from the Marília Formation (Bauru Group, Upper Cretaceous), Minas Berais, Brazil (Fee required)

Picture credit: Silvia Izquierdo

Velociraptor osmolskae

Godefroit, Currie, Li, Shang, and Dong (2008)
A new dromaeosaurid dinosaur Velociraptor osmolskae n. sp. is described on the basis of associated paired maxillae and a left lacrimal discovered in Campanian (Upper Cretaceous) deposits at Bayan Mandahu (Inner Mongolia, P. R. China) The maxilla of this new taxon is characterized by its long rostral plate and its enlarged, teardrop-shaped promaxillary fenestra, which is as large as the maxillary fenestra. The teeth are robust and the serrations are weakly developed on their distal carinae. This new taxon appears more closely related to Velociraptor mongoliensis, from the Campanian Djadokhta Formation in Mongolia, than to other dromaeosaurids described to date. The identification of the Bayan Mandahu Velociraptor as a distinct species is in keeping with the taxonomic distinction of the entire dinosaur fauna of this locality. Minor regional differences among Djadokhta-like localities in regards to their dinosaur faunas may reflect either some kind of geographic isolation, or small differences in their age or in their paleoenvironment.

Phylogenetic position (provisional): Theropoda | Tetanurae | Coelurosauria | Maniraptora | Paraves | Dromaeosauridae | Velociraptorinae

Journal article: A New Species Of Velociraptor (Dinosauria: Dromaeosauridae) From the Upper Cretaceous Of Northern China (Fee required)

Wulagasaurus dongi

Godefroit, Hai, Yu, and Lauters, 2008

Several hundred disarticulated dinosaur bones have been recovered from a large quarry at Wulaga (Heilongjiang Province, China), in the Upper Cretaceous (Maastrichtian) Yuliangze Formation. The Wulaga quarry can be regarded as a monodominant bonebed: more than 80% of the bones belong to a new lambeosaurine hadrosaurid, Sahaliyania elunchunorum gen. et sp. nov. This taxon is characterised by long and slender paroccipital processes, a prominent lateral depression on the dorsal surface of the frontal, a quadratojugal notch that is displaced ventrally on the quadrate, and a prepubic blade that is asymmetrically expanded, with an important emphasis to the dorsal side. Phylogenetic analysis shows that Sahaliyania is a derived lambeosaurine that forms a monophyletic group with the corythosaur and parasauroloph clades. Nevertheless, the exact position of Sahaliyania within this clade cannot be resolved on the basis of the available material. Besides Sahaliyania, other isolated bones display a typical hadrosaurine morphology and are referred to Wulagasaurus dongi gen. et sp. nov., a new taxon characterised by the maxilla pierced by a single foramen below the jugal process, a very slender dentary not pierced by foramina, and by the deltopectoral crest (on the humerus) oriented cranially. Phylogenetic analysis indicates that Wulagasaurus is the most basal hadrosaurine known to date. Phylogeographic data suggests that the hadrosaurines, and thus all hadrosaurids, are of Asian origin, which implies a relatively long ghost lineage of approximately 13 million years for basal hadrosaurines in Asia.

Phylogenetic position (provisional): Ornithopoda | Iguanodontia | Hadrosauroidea | Hadrosauridae | Hadrosaurinae

Journal article: New hadrosaurid dinosaurs from the uppermost
Cretaceous of northeastern China