Matthew Lamanna
Carnegie Museum of Natural History, Section of Vertebrate Paleontology, Department Member
- My research focuses on the morphology, evolution, and paleobiogeography of Cretaceous non-avian dinosaurs and birds, ... moreMy research focuses on the morphology, evolution, and paleobiogeography of Cretaceous non-avian dinosaurs and birds, particularly those from the Gondwanan (Southern Hemisphere) continents. I am especially interested in deciphering the role that Gondwanan fragmentation played in driving the evolution of terrestrial vertebrate faunas on its component landmasses. To that end, I have conducted fieldwork at Cretaceous localities in South America (Argentina), Africa (Egypt), Australia, and Antarctica.edit
We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia,... more
We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla-lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) 'tongue-like' ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infu...
Research Interests:
Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of... more
Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus—seemingly adapted for bearing extraordinary weight—and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges a...
Research Interests:
Research Interests:
Research Interests: Evolutionary Biology, Paleobiology, Earth Sciences, Geology, Paleontology, and 13 moreStratigraphy, Biogeochemistry, Paleoecology, Ecology, Dinosaur Paleontology, Antarctica, Cretaceous, Ecology and Evolutionary Biology, Vertebrates, Facies, Trace Fossil, Medicine and Health Sciences, and conglomerate
Research Interests:
Abstract: Epeiric seas stretched across vast regions of continents during the eustatic highs of the Late Cretaceous. Along these seas, low-energy conditions prevailed. Halophytic plants, including the tree-fern Weichselia reticulata,... more
Abstract: Epeiric seas stretched across vast regions of continents during the eustatic highs of the Late Cretaceous. Along these seas, low-energy conditions prevailed. Halophytic plants, including the tree-fern Weichselia reticulata, colonized these quiescent coasts, forming highly ...
Research Interests:
Research Interests:
The oviraptorosaurian theropod dinosaur clade Caenagnathidae has long been enigmatic due to the incomplete nature of nearly all described fossils. Here we describe Anzu wyliei gen. et sp. nov., a new taxon of large bodied caenagnathid... more
The oviraptorosaurian theropod dinosaur clade Caenagnathidae has long been enigmatic due to the incomplete nature of nearly all described fossils. Here we describe Anzu wyliei gen. et sp. nov., a new taxon of large bodied caenagnathid based primarily on three well-preserved partial skeletons. The specimens were recovered from the uppermost Cretaceous (upper Maastrichtian) Hell Creek Formation of North and South Dakota, and are therefore among the stratigraphically youngest known oviraptorosaurian remains. Collectively, the fossils include elements from most regions of the skeleton, providing a wealth of information on the osteology and evolutionary relationships of Caenagnathidae. Phylogenetic analysis reaffirms caenagnathid monophyly, and indicates that Anzu is most closely related to Caenagnathus collinsi , a taxon that is definitively known only from a mandible from the Campanian Dinosaur Park Formation of Alberta. The problematic oviraptorosaurs Microvenator and Gigantoraptor are recovered as basal caenagnathids, as has previously been suggested. Anzu and other caenagnathids may have favored well-watered floodplain settings over channel margins, and were probably ecological generalists that fed upon vegetation, small animals, and perhaps eggs.
Research Interests:
Titanosauriform sauropod dinosaurs are widely regarded as the most diverse and abundant large herbivores in Cretaceous paleoecosystems of Gondwanan landmasses. Nevertheless, remains of these animals are scarce in Late Cretaceous deposits... more
Titanosauriform sauropod dinosaurs are widely regarded as the most diverse and abundant large herbivores in Cretaceous paleoecosystems of Gondwanan landmasses. Nevertheless, remains of these animals are scarce in Late Cretaceous deposits of continental Africa and the then-conjoined Arabian Peninsula. Here we describe two new titanosauriform fossils from the lower Upper Cretaceous（Cenomanian）‘Kem Kem beds’ of Morocco that improve our understanding of the morphology and paleoecology of Afro-Arabian members of this clade. One specimen is a nearly complete, well-preserved anterior dorsal vertebra that pertains to a large-bodied member of Somphospondyli, possibly to a basal titanosaurian. The second specimen is a partial ischium that is not identifiable beyond Somphospondyli; nevertheless, the element is significant in exhibiting numerous tooth marks that we attribute to a very large carnivorous dinosaur, probably a carcharodontosaurid or Spinosaurus. These feeding traces constitute direct evidence that sauropods were a food source for at least one African Late Cretaceous theropod. It is presently uncertain whether or not the new titanosauriform elements pertain to any of three named genera from the early Late Cretaceous of Africa (Aegyptosaurus, Paralititan, and Angolatitan), or whether they represent previously undescribed taxa.
Research Interests:
Although recent discoveries from Lower Cretaceous sediments in northeastern China have greatly improved our understanding of the initial stages of avian diversification in eastern Asia, the early evolution of Aves elsewhere on the... more
Although recent discoveries from Lower Cretaceous sediments in northeastern China have greatly improved our understanding of the initial stages of avian diversification in eastern Asia, the early evolution of Aves elsewhere on the continent remains poorly understood. In 2004, a collaborative field effort directed by personnel from the Chinese Academy of Geological Sciences and Carnegie Museum of Natural History recovered multiple partial to nearly complete avian skeletons from outcrops of the Lower Cretaceous Xiagou Formation exposed in the Changma Basin of northwestern Gansu Province, China. Here we describe a thrush−sized partial skeleton comprised of a fragmentary pelvic girdle and largely complete hind limbs. A phylogenetic analysis of 20 avian ingroup taxa and 169 anatomical characters places the specimen in Enantiornithes, and within that clade, in Euenantiornithes. When coupled with additional recent discoveries from the Changma Basin, the new skeleton improves our understanding of early avian evolution and
diversification in central Asia.
diversification in central Asia.
Research Interests:
Ornithischian dinosaurs are uncommon elements in Late Cretaceous faunal assemblages of many Gondwanan landmasses, particularly Africa. The best-documented post-Cenomanian record of purported ornithischian body fossils from Africa consists... more
Ornithischian dinosaurs are uncommon elements in Late Cretaceous faunal assemblages of many Gondwanan landmasses, particularly Africa. The best-documented post-Cenomanian record of purported ornithischian body fossils from Africa consists of a left humerus, with associated cranial and costal fragments, from the Santonian Campanian Quseir Formation of Kharga Oasis, Egypt (Fig. 1) (Awad and Ghobrial, 1966). We show that this specimen pertains instead to a dyrosaurid crocodyliform, and restrict known African ornithischian body fossils to pre-Turonian sediments. The apparent absence of this dinosaur clade from the post- Cenomanian Late Cretaceous of Africa is probably a consequence of limited sampling; nevertheless, a comparable ornithischian absence from coeval sediments in Madagascar and possibly Indo-Pakistan constitutes a notable faunal similarity among these landmasses.
Research Interests:
A nearly complete, well-preserved maxilla of an abelisaurid theropod from the early Late Cretaceous (middle Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of Chubut, Argentina represents the first definitive member of the... more
A nearly complete, well-preserved maxilla of an abelisaurid theropod from the early Late Cretaceous (middle Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of Chubut, Argentina represents the first definitive member of the abelisaurid clade from pre-Senonian (Coniacian–Maastrichtian) deposits. The new maxilla shares derived characters with the maxillae of Carnotaurus and Majungatholus, and with AMNH 1955, a maxilla previously referred to Indosuchus, suggesting that it pertains to the abelisaurid subclade Carnotaurinae. Abelisaurus shares apomorphic characters with Carnotaurinae, but many of these characters are also found in the carcharodontosaurid allosauroid Giganotosaurus. As it is known only from cranial material lacking carnotaurine synapomorphies, Abelisaurus may represent a late-surviving carcharodontosaurid derivative.
The presence of the Bajo Barreal predator in the early Late Cretaceous indicates that the origin of Abelisauridae had occurred by then. The occurrence of the new maxilla is nearly concurrent with the accepted interval of tectonic divergence between South America and Africa. Its discovery thus weakens support for the recent hypothesis that the abelisaurid clade could not have penetrated Africa. The known occurrence of Abelisauridae may reflect a former pan- Gondwanan distribution, and is thus of limited utility in the support of Late Cretaceous paleogeographic hypotheses.
The presence of the Bajo Barreal predator in the early Late Cretaceous indicates that the origin of Abelisauridae had occurred by then. The occurrence of the new maxilla is nearly concurrent with the accepted interval of tectonic divergence between South America and Africa. Its discovery thus weakens support for the recent hypothesis that the abelisaurid clade could not have penetrated Africa. The known occurrence of Abelisauridae may reflect a former pan- Gondwanan distribution, and is thus of limited utility in the support of Late Cretaceous paleogeographic hypotheses.
Research Interests:
Three-dimensional specimens of the volant fossil bird Gansus yumenensis from the Early Cretaceous Xiagou Formation of northwestern China demonstrate that this taxon possesses advanced anatomical features previously known only in Late... more
Three-dimensional specimens of the volant fossil bird Gansus yumenensis from the Early Cretaceous Xiagou Formation of northwestern China demonstrate that this taxon possesses advanced anatomical features previously known only in Late Cretaceous and Cenozoic ornithuran birds. Phylogenetic analysis recovers Gansus within the Ornithurae, making it the oldest known member of the clade. The Xiagou Formation preserves the oldest known ornithuromorph-dominated avian assemblage. The anatomy of Gansus, like that of other non-neornithean (nonmodern) ornithuran birds, indicates specialization for an amphibious life-style, supporting the hypothesis that modern birds originated in aquatic or littoral niches.
Research Interests:
Research Interests:
We describe a giant titanosaurid sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has produced three Tyrannosaurus-sized theropods and numerous other vertebrate taxa.... more
We describe a giant titanosaurid sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has produced three
Tyrannosaurus-sized theropods and numerous other vertebrate taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since 1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous sauropod. The autochthonous scavenged skeleton was preserved in mangrove deposits, raising the possibility that titanosaurids and their predators habitually entered such environments.
Tyrannosaurus-sized theropods and numerous other vertebrate taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since 1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous sauropod. The autochthonous scavenged skeleton was preserved in mangrove deposits, raising the possibility that titanosaurids and their predators habitually entered such environments.
Research Interests:
Titanosaurian sauropod dinosaurs were the most diverse and abundant large-bodied herbivores in the southern continents during the final 30 million years of the Mesozoic Era. Several titanosaur species are regarded as the most massive... more
Titanosaurian sauropod dinosaurs were the most diverse and abundant large-bodied herbivores in the southern continents during the final 30 million years of the Mesozoic Era. Several titanosaur species are regarded as the most massive land-living animals yet discovered; nevertheless, nearly all of these giant titanosaurs are known only from very incomplete fossils, hindering a detailed understanding of their anatomy. Here we describe a new and gigantic titanosaur, Dreadnoughtus schrani,fromUpper Cretaceous sediments in southern Patagonia, Argentina. Represented by approximately 70% of the postcranial skeleton, plus craniodental remains, Dreadnoughtus is the most complete giant titanosaur yet discovered, and provides new insight into the morphology and evolutionary history of these colossal animals. Furthermore, despite its estimated mass of about 59.3 metric tons, the bone histology of the Dreadnoughtus type specimen reveals that this individual was still growing at the time of death.
Research Interests:
Research Interests:
We describe an articulated specimen of the titanosaurian sauropod Epachthosaurus sciuttoi from the early Late Cretaceous Bajo Barreal Formation of Chubut Province, central Patagonia, Argentina. The skeleton was found in tuffaceous... more
We describe an articulated specimen of the titanosaurian sauropod Epachthosaurus sciuttoi from the early Late Cretaceous Bajo Barreal Formation of Chubut Province, central Patagonia, Argentina. The skeleton was found in tuffaceous sandstone, with its hindlimbs flexed and its forelimbs widely extended. It is slightly deformed on its left side. The skull, neck, four or five cranial dorsal vertebrae, and several distal caudals are missing. Epachthosaurus is diagnosed by the following autapomorphies: middle and caudal dorsal vertebrae with accessory articular processes extending ventrolaterally from the hyposphene, a strongly developed intraprezygapophyseal lamina, and aliform processes projecting laterally from the dorsal portion of the spinodiapophyseal lamina; hyposphene-hypantrum articulations in caudals 1–14; and a pedal phalangeal formula of 2-2-3-2-0. The genus shares the following apomorphies with various titanosaurians: caudal dorsal vertebrae with ventrally expanded posterior centrodiapophyseal laminae; six sacral vertebrae; an ossified ligament or tendon dorsal to the sacral neural spines; procoelous proximal, middle, and distal caudal centra with well-developed distal articular condyles; semilunar sternal plates with cranioventral ridges; humeri with squared proximolateral margins and proximolateral processes; unossified carpals; strongly reduced manual phalanges; craniolaterally expanded, nearly horizontal iliac preacetabular processes; pubes proximodistally longer than ischia; and transversely expanded ischia. Epachthosaurus is considered the most basal titanosaurian known with procoelous caudal vertebrae.
Research Interests:
Due to their abundance, taxonomic and morphological diversity, wide range of body sizes and broad geographical distribution, titanosaurian sauropods were one of the most important Cretaceous herbivorous dinosaur groups. Consequently,... more
Due to their abundance, taxonomic and morphological diversity, wide range of body sizes and broad geographical distribution, titanosaurian sauropods were one of the most important Cretaceous herbivorous dinosaur groups. Consequently, titanosaurs constitute one of the best samples in which to evaluate the relationship between bony structures and unpreserved soft-tissues within Sauropoda. We reconstruct the morphology and interpret the implications of selected soft-tissues associated with the titanosaurian caudal skeleton. These tissues, especially the M. caudofemoralis longus (CFL), exerted a considerable influence on the anatomy of the caudal vertebrae and haemal arches. In all studied titanosaurian taxa,the reconstructed caudofemoral musculature corresponds to one of three principal morphotypes that accord with previously recognised phylogenetic patterns within the clade. Basal titanosaurians had an elongate M. CFL that extended for much of the proximal half of the tail; in saltasaurines, this muscle was much shorter. Non-saltasaurine lithostrotians exhibited an intermediate condition. Furthermore, the differing position of the fourth trochanter, and therefore, the insertion of the caudofemoral muscles, among various titanosaurian taxa suggests distinctions in the locomotor function of these animals.
Research Interests:
A new sauropod, Aeolosaurus colhuehuapensis . sp. nov., based on an articulated caudal series recovered from an emergent island in Lago Colhué Huapi, Chubut Province is described. This series is characterized by neural arches located very... more
A new sauropod, Aeolosaurus colhuehuapensis . sp. nov., based on an articulated caudal series recovered from an emergent island in Lago Colhué Huapi, Chubut Province is described. This series is characterized by neural arches located very anteriorly above the centrum and inclined forward; well-developed prezygapophyses projecting forward and upward, and wide articular facets in the anterior caudals. Aeolosaurus colhuehuapensis sp. nov. is unique by the presence of a marked and deep fossa between the transverse process and the base of the neural spine in the most anterior caudal vertebrae; a slender lamina that connects the base of the prespinal lamina with the lower part of the articular facet in the medial part of the prezygapophysis, defining a fossa on both sides of the prespinal lamina; posterior condyle centrally placed in the entire caudal series. The genus Aeolosaurus is recorded in the Campanian-Maastrichtian in Argentina and Brazil, and is considered part of a faunal association with hadrosaurids, Madtsoiinae, Chelidae, Sudamericidae, and non-tribosphenic Theria in floodplain or littoral environments. Its presence in the Upper Member of the Bajo Barreal Formation, along with other paleontological records from the same locality, and geologic observations allow us to assign preliminarily a Campanian-Maastrichtian? age for the upper levels of this stratigraphic unit outcropping in the southeast of Lago Colhué Huapi, Chubut Province.
Research Interests:
We describe a new titanosaurian sauropod dinosaur, Borealosaurus wimani gen. et sp. nov., based on distinctive mid-distal caudal vertebra from the early Late Cretaceous Sunjiawan Formation exposed in the Shuangmiao village of Beipiao in... more
We describe a new titanosaurian sauropod dinosaur, Borealosaurus wimani gen. et sp. nov., based on distinctive mid-distal caudal vertebra from the early Late Cretaceous Sunjiawan Formation exposed in the Shuangmiao village of Beipiao in Liaoning, China. We provisionally refer an isolated tooth crown, a middle caudal vertebra, and a right humerus from the same locality and horizon to this taxon. Borealosaurus is distinguished from other sauropods in its possession of opisthocoelous mid-distal caudal vertebrae. The occurrence of opisthocoelous caudals in Borealosaurus and the Mongolian sauropod Opisthocoelicaudia raises the possibility that these taxa pertain to an as-yet unrecognized titanosaurian subclade endemic to the Cretaceous Asia.
Research Interests:
We describe Katepensaurus goicoecheai, gen. et sp. nov., a diplodocoid sauropod dinosaur from the Bajo Barreal Formation (Upper Cretaceous: Cenomanian–Turonian) of south-central Chubut Province, central Patagonia, Argentina. The holotypic... more
We describe Katepensaurus goicoecheai, gen. et sp. nov., a diplodocoid sauropod dinosaur from the Bajo Barreal Formation (Upper Cretaceous: Cenomanian–Turonian) of south-central Chubut Province, central Patagonia, Argentina. The holotypic specimen is a closely associated partial axial skeleton that includes cervical, dorsal, and caudal vertebrae. The dorsal vertebrae of Katepensaurus exhibit the following distinctive characters that we interpret as autapomorphies: (1) internal lamina divides lateral pneumatic fossa of centrum; (2) vertical ridges or crests present on lateral surface of vertebra, overlying neurocentral junction; (3) pair of laminae in parapophyseal centrodiapophyseal fossa; (4) transverse processes perforated by elliptical fenestrae; and (5) well-defined, rounded fossae on lateral aspect of postzygapophyses. Based on the results of previous phylogenetic analyses, we regard the new taxon as a member of Rebbachisauridae; more specifically, it may pertain to Limaysaurinae, a rebbachisaurid subclade that, to date, is definitively known only from southern South America. As currently understood, the rebbachisaurid fossil record suggests that the clade achieved its greatest taxonomic diversity within a few million years of its extinction during the early Late Cretaceous.
Research Interests:
We describe new and redescribe previously discovered sauropod dinosaur material from the Upper Cretaceous (middle Cenomanian-Turonian) Bajo Barreal Formation of south-central Chubut Province, central Patagonia, Argentina. The remains... more
We describe new and redescribe previously discovered sauropod dinosaur material from the Upper Cretaceous (middle Cenomanian-Turonian) Bajo Barreal Formation of south-central Chubut Province, central Patagonia, Argentina. The remains consist of associated and isolated axial skeletal elements recovered from three separate localities, and are herein assigned to the morphologically aberrant Rebbachisauridae clade. Several of the fossils exhibit osteological characters that were previously undocumented in rebbachisaurids, enhancing our understanding of the morphological diversity of this enigmatic sauropod group. In particular, the Bajo Barreal material demonstrates the occurrence within Rebbachisauridae of bifurcate neural spines in cervical vertebrae and well-developed, presumably pneumatic fossae in caudal vertebrae; among Diplodocoidea, these distinctive morphologies had previously been recognized only in flagellicaudatans. Furthermore, the Bajo Barreal fossils constitute the southernmost known occurrences of Diplodocoidea, adding to the globally sparse Late Cretaceous record of these sauropods and augmenting our knowledge of central Patagonian terrestrial vertebrate assemblages during this interval.
Research Interests:
More than any other sauropod dinosaur group, the long-necked herbivores belonging to Diplodocoidea have been defined by their skulls. Their unique skull shape, which is extremely elongate antorbitally, with a transversely broad, square... more
More than any other sauropod dinosaur group, the long-necked herbivores belonging to Diplodocoidea have been defined by their skulls. Their unique skull shape, which is extremely elongate antorbitally, with a transversely broad, square snout packed at its anterior extreme with narrow crowned, pencil-like teeth, has served as a touchstone for describing the biology of these animals ever since the discovery of the first skull in the late 19th century. In particular, the unusual diplodocoid skull has been discussed frequently in the context of examining feeding behavior, spawning hypotheses ranging from branch stripping, propalinal shearing, and aquatic plant ‘grazing.’ Here, we describe a juvenile skull of Diplodocus (Carnegie Museum 11255) that does not share the unusually blunted snout and anteriorly sequestered teeth seen in adult specimens, suggesting that adults and juveniles may have differed greatly in their feeding behavior, an ontogenetic distinction that may be unique among sauropodomorphs.
Research Interests:
Despite increasingly intensive paleontological sampling, Cretaceous terrestrial vertebrates from continental Africa remain relatively poorly known, frustrating efforts to characterize paleoecosystems in the region, as well as the... more
Despite increasingly intensive paleontological sampling, Cretaceous terrestrial vertebrates from continental Africa remain relatively poorly known, frustrating efforts to characterize paleoecosystems in the region, as well as the paleobiogeography of the southern continents during this interval. Here we describe the partial skeleton of a large bodied theropod dinosaur from the Early Cretaceous (early Aptian, ~125–120 Ma) of Libya. The specimen consists of associated elements (two incomplete dorsal vertebrae, a proximal caudal centrum, a partial proximal caudal neural arch, the distal right femur, and the mostly complete right tibia) and is referable to the widespread ceratosaurian clade Abelisauroidea. The discovery adds to the growing record of abelisauroids from mainland Africa, and firmly establishes the presence of the clade on the continent prior to its final separation from South America. Indeed, the age of the Libyan theropod predates or is penecontemporaneous with the accepted timing of fragmentation of most major Gondwanan landmasses, supporting the hypothesis that abelisauroids could have dispersed throughout the southern continents before land connections between these areas were severed. Moreover, the considerable size of the Libyan form challenges assertions that abelisauroids were ecologically subordinate to basal tetanuran theropods in Early and middle Cretaceous paleoenvironments of Gondwana.
Research Interests:
Recent paleogeographic scenarios postulate the isolation of continental Africa during the Late Cretaceous. The absence of abelisaurid theropods from Upper Cretaceous African strata offered as support of hypothesized African isolation... more
Recent paleogeographic scenarios postulate the isolation of continental Africa during the Late Cretaceous. The absence of abelisaurid theropods from Upper Cretaceous African strata offered as support of hypothesized African isolation with the acknowledgement that the paucity of African abelisaurids may be mostly an issue of sampling. Here we report on a shed theropod tooth from the Upper Cretaceous (Maastrichtian, ∼70 Ma) Duwi Formation of Egypt. The tooth was referred to the Malagasy abelisaurid “Megalosaurus” crenatissimus (=Majungasaurus crenatissimus) in 1921. A discriminant function analysis was run to test for morphological congruence between the Egyptian tooth and the dentitions of 24 theropod taxa. The analysis correctly classified 96.6% of the teeth in the sample and assigned the ooth to Majungasaurus. As current paleogeographic reconstructions posit Madagascar had attained its current position relative to Africa before the Late Cretaceous, it is unlikely that the Egyptian tooth actually pertains to Majungasaurus. Nevertheless, its classification as an abelisaurid supports its referral to the clade. This tooth thus constitutes defensible evidence of an abelisaurid from the post-Cenomanian Cretaceous of mainland Africa. Combined with recent discoveries of abelisaurids in Niger and Morocco, the result indicates that Abelisauridae was a diverse group in Africa during the Cretaceous, existing in multiple places for at least ∼25 Ma and weakens support for hypotheses of an isolated Africa during the Late Cretaceous.
Research Interests:
Research Interests:
We report an isolated right lacrimal of a tyrannosaurid theropod dinosaur, probably from the Upper Cretaceous (upper Campanian) Judith River Formation of Fergus County, Montana. The lacrimal was originally associated with the holotype of... more
We report an isolated right lacrimal of a tyrannosaurid theropod dinosaur, probably from the Upper Cretaceous (upper Campanian) Judith River Formation of Fergus County, Montana. The lacrimal was originally associated with the holotype of the giant crocodylian Deinosuchus rugosus, but was later identified as that of a tyrannosaurid. It is of comparable size to the corresponding element in the gigantic Maastrichtian tyrannosaurid Tyrannosaurus. Moreover, comparison of the lacrimal to those of other tyrannosaurids tentatively supports its referral to this genus. Consequently, provided that its stratigraphic provenance has been correctly identified, the specimen represents the oldest-known North American record of a Tyrannosaurus-sized tyrannosaurid, and possibly the most ancient occurrence of this genus yet documented.
Research Interests:
We herein describe an associated partial postcranial skeleton of a theropod dinosaur discovered in the Lower Cretaceous Xinminpu Group of the Yujingzi Basin, in the Jiuquan area of Gansu Province, northwestern China. Features of its... more
We herein describe an associated partial postcranial skeleton of a theropod dinosaur discovered in the Lower Cretaceous Xinminpu Group of the Yujingzi Basin, in the Jiuquan area of Gansu Province, northwestern China. Features of its humerus, such as strongly expanded proximal and distal ends, a well developed medial tuberosity, distal condyles expressed on the humeral cranial surface, and a hypertrophied entepicondyle, definitively establish the therizinosauroid affinities of the specimen. It differs from other therizinosauroids in having a shallow, poorly demarcated glenoid fossa with a prominent rounded and striated tumescence on the dorsomedial surface of its scapular portion, and a pubis with a strongly concave cranial margin. It represents a new taxon, Suzhousaurus megatherioides gen. et sp. nov. Cladistic analysis recovers Suzhousaurus as the sister taxon of Nothronychus mckinleyi from the mid-Cretaceous of western North America; together, they are basal members of the Therizinosauroidea, more derived than the Early Cretaceous Falcarius and Beipiaosaurus but less derived than Alxasaurus and the Therizinosauridae. Along with “Nanshiungosaurus” bohlini from possibly coeval beds in the Mazongshan area of northern-most Gansu, Suzhousaurus represents one of the largest-known Early Cretaceous therizinosauroids, demonstrating that this clade attained considerable body size early in its evolutionary history.
Research Interests:
In recent years, the Lower Cretaceous (Aptian) Xiagou Formation has yielded approximately 100 avian partial skeletons, many with soft-tissue traces, from sites in the Changma Basin of Gansu Province, north-western China. The most abundant... more
In recent years, the Lower Cretaceous (Aptian) Xiagou Formation has yielded approximately 100 avian partial skeletons, many with soft-tissue traces, from sites in the Changma Basin of Gansu Province, north-western China. The most abundant taxon amongst these is the ornithuromorph Gansus yumenensis, but enantiornithines have also been identified in the sample. Here we describe two incomplete, semi-articulated appendicular skeletons, the first consisting of a partial left pelvic girdle and complete pelvic limb, and the second comprised of a nearly complete right pelvic limb. Both specimens bear characteristics diagnostic of Enantiornithes, and are referred to a new taxon, Qiliania graffini gen. et sp. nov. The exceptional, three-dimensional preservation of these specimens (compared to the crushed, nearly two-dimensional condition of most other Early Cretaceous avian fossils) reveals new information regarding enantiornithine anatomy, evolution, and diversity.
Research Interests:
Research Interests:
A new specimen of an enantiornithean bird from the Lower Cretaceous Xiagou Formation of Gansu Province, northwestern China, consists of an articulated distal left humerus, ulna, radius, carpus, and manus. The specimen may represent a... more
A new specimen of an enantiornithean bird from the Lower Cretaceous Xiagou Formation of Gansu Province, northwestern China, consists of an articulated distal left humerus, ulna, radius, carpus, and manus. The specimen may represent a primitive enantiornithean because it lacks a longitudinal sulcus on the radius, has incompletely fused alular and major metacarpals, and possibly retains a remnant of a second phalanx on the minor digit. It differs from all other known enantiornitheans, and exhibits possible autapomorphies, including peculiar, flat humeral epicondyles, a pair of eminences on the distal minor metacarpal, and an enormous flexor tuberculum on the alular ungual. The specimen probably pertains to the same taxon as a previously described enantiornithean arm from Changma; the incompleteness of the taxon precludes erecting a new name, but it provides new information concerning enantiornithean diversity in the Early Cretaceous of central Asia.
Research Interests:
Finely−bedded lacustrine deposits of the Aptian (Lower Cretaceous) Xiagou Formation exposed in the Changma Basin of Gansu Province, northwestern China, have yielded numerous fossil vertebrate remains, including approximately 100 avian... more
Finely−bedded lacustrine deposits of the Aptian (Lower Cretaceous) Xiagou Formation exposed in the Changma Basin of Gansu Province, northwestern China, have yielded numerous fossil vertebrate remains, including approximately 100 avian specimens. Though the majority of these birds appear referable to the ornithuromorph Gansus yumenensis, a number of enantiornithine fossils have also been recovered. Here we report on a specimen consisting of a complete, three−dimensionally preserved sternum, furcula, and sternal ribs that represents a second ornithuromorph taxon from the Xiagou Formation at Changma. The fossil exhibits morphologies that distinguish it from all previously−known Xiagou birds and demonstrate that it represents a derived non−ornithurine member of Ornithuromorpha. Though it is morphologically distinct from the equivalent elements of all other described ornithuromorphs, the material is too incomplete to justify the erection of a new taxon. Nonetheless, it increases the taxonomic diversity of the Xiagou avifauna, thereby expanding our knowledge of Early Cretaceous avian diversity and evolution.
Research Interests:
Research Interests:
Microbodies associated with fossil feathers, originally attributed to microbial biofilm, have been reinterpreted as melanosomes: pigment-containing, eukaryotic organelles. This interpretation generated hypotheses regarding coloration in... more
Microbodies associated with fossil feathers, originally attributed to microbial biofilm, have been reinterpreted as melanosomes: pigment-containing, eukaryotic organelles. This interpretation generated hypotheses regarding coloration in non-avian and avian dinosaurs. Because melanosomes and microbes overlap in size, distribution and morphology, we reevaluate both hypotheses. We compare melanosomes within feathers of extant chickens with patterns induced by microbial overgrowth on the same feathers, using scanning (SEM), field emission (FESEM) and transmission (TEM) electron microscopy. Melanosomes are always internal, embedded in a morphologically distinct keratinous matrix. Conversely, microbes grow across the surface of feathers in continuous layers, more consistent with published images from fossil feathers. We compare our results to both published literature and new data from a fossil feather ascribed to Gansus yumenensis (ANSP 23403). ‘Mouldic impressions’ were observed in association with both the feather and sediment grains, supporting a microbial origin. We propose criteria for distinguishing between these two microbodies.
Research Interests:
A new genus and species of basal neoceratopsian dinosaur, Auroraceratops rugosus, is reported based on material from the Early Cretaceous Xinminpu Group in the Gongpoquan Basin of Gansu Province, China. Auroraceratops is represented by a... more
A new genus and species of basal neoceratopsian dinosaur, Auroraceratops rugosus, is reported based on material from the Early Cretaceous Xinminpu Group in the Gongpoquan Basin of Gansu Province, China. Auroraceratops is represented by a nearly complete skull and low jaws, and different greatly from all other neoceratopsians by its considerable breadth of the nasals, fungiform expansion of the dorsal end of the lacrimal, highly developed rugosity of the jugal, dentary and surangular, and inflated, striated premaxillary teeth. The finding of Auroraceratops adds diversity and helps elucidate the evolution of basal neoceratopsian dinosaurs.
Research Interests:
We present a reinterpretation of the bones previously identified as ossified hyoid elements in the Asian Late Cretaceous ceratopsian dinosaur Protoceratops andrewsi Granger and Gregory, 1923. Comparisons with other ceratopsian skeletons... more
We present a reinterpretation of the bones previously identified as ossified hyoid elements in the Asian Late Cretaceous ceratopsian dinosaur Protoceratops andrewsi Granger and Gregory, 1923. Comparisons with other ceratopsian skeletons indicate that the tetraradiate bone tentatively regarded as a first ceratobranchial is actually an incomplete middle cervical rib, and the larger, flattened elements identified as second ceratobranchials are partial sternal plates. As in nearly all other ornithischian dinosaurs for which this area of the skeleton is known, the ossified hyoid apparatus of P. andrewsi probably consisted of a pair of rod-like first ceratobranchials; two additional, splint-like or sheet-like bones that are most frequently interpreted as ceratohyals may also have been present.
Research Interests:
An associated partial postcranial skeleton is described as the third definitive ornithopod dinosaur record from the Upper Cretaceous Bajo Barreal Formation of central Patagonia, Argentina. Specifically, the specimen was recovered from... more
An associated partial postcranial skeleton is described as the third definitive ornithopod dinosaur record from the Upper Cretaceous Bajo Barreal Formation of central Patagonia, Argentina. Specifically, the specimen was recovered from the uppermost Cretaceous (Campanian -?Maastrichtian) Upper Member of the Bajo Barreal exposed on an ephemeral island in the southeastern portion of Lago Colhué Huapi in southern Chubut Province. Identifiable elements of the skeleton include four incomplete dorsal vertebrae, three partial anterior caudal vertebrae, a middle caudal neural arch, an incomplete posterior caudal vertebra, a dorsal rib fragment, the right calcaneum, and portions of the left metatarsal III and right metatarsal IV. Comparisons with corresponding elements in other ornithischians indicate that the material pertains to a medium-sized, non-hadrosaurid ornithopod. In particular, the morphology of the calcaneum is characteristic of ornithopods of this "grade". The new discovery augments our understanding of the latest Cretaceous terrestrial vertebrate assemblage of central Patagonia and adds to the generally meager record of ornithischians in the Late Cretaceous of the Southern Hemisphere.
Research Interests:
The Upper Cretaceous (Maastrichtian) Sandwich Bluff Member of the López de Bertodano Formation is well exposed on Vega Island in the James Ross Basin off the northeastern coast of the Antarctic Peninsula. Although this unit is one of the... more
The Upper Cretaceous (Maastrichtian) Sandwich Bluff Member of the López de Bertodano Formation is well exposed on Vega Island in the James Ross Basin off the northeastern coast of the Antarctic Peninsula. Although this unit is one of the richest sources of end-Cretaceous vertebrate fossils in Antarctica, it is also one of the least sedimentologically and stratigraphically characterized units in the basin. New facies and stratigraphic analyses of the Sandwich Bluff Member and the underlying Cape Lamb Member of the Snow Hill Island Formation were performed in tandem with intensive prospecting for fossil vertebrates and stratigraphic assessment of historic paleontological localities on Vega Island. This effort has led to a revised stratigraphy for the Sandwich Bluff Member and the precise stratigraphic placement of important terrestrial and marine vertebrate fossil localities. Facies analysis reveals a fining and shallowing upward trend through the section that culminates in a newly recognized sequence boundary near the top of the Sandwich Bluff Member, followed by the deposition of a previously unrecognized, 6 m-thick, matrix-supported pebble-cobble conglomerate of probable alluvial origin. Immediately overlying this unit, well-developed Thalassinoides burrow networks in fine-grained transgressive sandstones and siltstones indicate a rapid return to marine conditions. A similar stratigraphic pattern is well documented at the top of the López de Bertodano Formation and the base of the overlying (Paleocene) Sobral Formation on Seymour Island in the southern part of the basin. Although no fossils were recovered to constrain the age of the upper 10-15 m of the succession on Vega Island that preserves the newly recognized upper sequence boundary, strata below this level can be confidently placed within the Manumiella bertodano interval zone, which extends to a short distance below the K– Pg boundary on Seymour Island. Hence, based on sequence stratigraphic and lithostratigraphic evidence, the uppermost 10–15 m of the succession on Vega Island may encompass the Cretaceous–Paleogene boundary together with a few meters of the Paleocene Sobral Formation.
Research Interests:
The Albian-Cenomanian Alcântra Formation of northeastern Brazil preserves the most diverse continental vertebrate fauna of this age yet known from northern South America. The Alcântra vertebrate assemblage, consisting of elasmobranches,... more
The Albian-Cenomanian Alcântra Formation of northeastern Brazil preserves the most diverse continental vertebrate fauna of this age yet known from northern South America. The Alcântra vertebrate assemblage, consisting of elasmobranches, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs, displays close similarities to contemporaneous faunas from North Africa. The co-occurrence of as many as eight freshwater or estuarine fish taxa (Onchopristis, Bartschichthys, Lepidotes, Stephanodus, Mawsonia, Arganodus, Ceratodus africanus, and possibly Ceratodus humei) and up to seven terrestrial archosaur taxa (Sigilmassasaurus, Rebbachisauridae, Baryonychinae, Spinosaurinae, Carcharodontosauridae, possibly Pholidosauridae, and doubtfully Bahariasaurus) suggests that a land route connecting northeastern Brazil and North Africa existed at least until the Albian. Interestingly, most components of this mid-Cretaceous northern South American/North African assemblage are not shared with coeval southern South American faunas, which are themselves characterized by a number of distinct freshwater and terrestrial vertebrate taxa (e.g., chelid turtles, megaraptoran and unenlagiine theropods). These results suggest that, although mid-Cretaceous faunal interchange was probably possible between northern South American and North Africa, paleogeographic, paleoclimatic, and/or paleoenvironmental barriers may have hindered continental vertebrate dispersal between northern and southern South America during this time.
Research Interests:
Epeiric seas stretched across vast regions of continents during the eustatic highs of the Late Cretaceous. Along these seas, low-energy conditions prevailed. Halophytic plants, including the tree-fern Weichselia reticulata, colonized... more
Epeiric seas stretched across vast regions of continents during the eustatic highs of the Late Cretaceous. Along these seas, low-energy conditions prevailed. Halophytic plants, including the tree-fern Weichselia reticulata, colonized these quiescent coasts, forming highly productive mangrove ecosystems.
The morphodynamic behavior of Cretaceous epeiric coasts can be better understood though analogy with similar environments that exist today. The Ten Thousand Islands coast of southwestern Florida provides an ideal analog. The low-energy wave regime and attenuated tidal range is probably representative of conditions that prevailed along Cretaceous epeiric coasts. The invasion of the littoral zone along the Ten Thousand Islands coast by robust mangrove vegetation has led to a bimodal response to Holocene sea level rise. Both transgressive and regressive behaviors occur simultaneously along different reaches, creating a very complex stratigraphic record.
Late Cretaceous coastal deposits exposed in the Bahariya Oasis of Egypt record the development of a similar low-energy mangrove coast in response to rising Cenomanian sea level. These deposits record coeval transgressive and regressive sequences that appear to have resulted from: 1) heterogeneities in the paleolittoral system, and; 2) colonization of the littoral zone by mangrove vegetation, that includes Weichselia reticulata and possibly other mangrove species. Study of the modern analog provided by the Ten Thousand Islands coast has facilitated a more complete understanding of the paleomorphodynamics of low-energy Mesozoic epeiric coasts. Conversely, the study of ancient coastal deposits, laid down in Cretaceous “hothouse” conditions, holds implications for understanding coastal response to modern global warming and sea level rise.
The morphodynamic behavior of Cretaceous epeiric coasts can be better understood though analogy with similar environments that exist today. The Ten Thousand Islands coast of southwestern Florida provides an ideal analog. The low-energy wave regime and attenuated tidal range is probably representative of conditions that prevailed along Cretaceous epeiric coasts. The invasion of the littoral zone along the Ten Thousand Islands coast by robust mangrove vegetation has led to a bimodal response to Holocene sea level rise. Both transgressive and regressive behaviors occur simultaneously along different reaches, creating a very complex stratigraphic record.
Late Cretaceous coastal deposits exposed in the Bahariya Oasis of Egypt record the development of a similar low-energy mangrove coast in response to rising Cenomanian sea level. These deposits record coeval transgressive and regressive sequences that appear to have resulted from: 1) heterogeneities in the paleolittoral system, and; 2) colonization of the littoral zone by mangrove vegetation, that includes Weichselia reticulata and possibly other mangrove species. Study of the modern analog provided by the Ten Thousand Islands coast has facilitated a more complete understanding of the paleomorphodynamics of low-energy Mesozoic epeiric coasts. Conversely, the study of ancient coastal deposits, laid down in Cretaceous “hothouse” conditions, holds implications for understanding coastal response to modern global warming and sea level rise.
Research Interests:
We present an annotated and illustrated catalogue of all original fossils, casts, and sculpted replicas of pterosaur specimens from the Upper Jurassic Solnhofen limestones of southern Germany that are housed at Carnegie Museum of Natural... more
We present an annotated and illustrated catalogue of all original fossils, casts, and sculpted replicas of pterosaur specimens from the Upper Jurassic Solnhofen limestones of southern Germany that are housed at Carnegie Museum of Natural History (Pittsburgh, Pennsylvania, U.S.A.). The museum obtained its substantial Solnhofen pterosaur fossil collection—almost certainly the largest currently held outside of Europe—as part of its purchase of the vast private collection of the Belgian Baron Ernest de Bayet in 1903. Original fossils include six partial to nearly complete skeletons and a beautifully preserved skull of the rhamphorhynchine Rhamphorhynchus muensteri (Goldfuss, 1831), two skeletons of the ctenochasmatid pterodactyloid Aurorazhdarcho micronyx (von Meyer, 1856), and one large pterodactyloid partial appendicular skeleton of indeterminate affinity. Three of the fossils preserve significant soft tissues, and one of these is also among the very few specimens of Rhamphorhynchus von Meyer, 1847 known to include probable gut contents (in this case, fragmentary fish remains). Two other Rhamphorhynchus fossils have been prepared nearly free of sediment in three dimensions. Despite the significance of the Carnegie Museum’s Solnhofen pterosaur collection, it has, in general, been underutilized by the paleontological community. The primary purpose of this catalogue is therefore to increase awareness, and ideally study, of this scientifically and historically important collection of Late Jurassic flying reptiles.
Research Interests:
A newly discovered osteichthyan ectopterygoid from the Upper Cretaceous (lower Cenomanian) Bahariya Formation of the Bahariya Oasis, Egypt, is nearly identical to the holotypic specimen of Polypterus? bartheli from the same area and... more
A newly discovered osteichthyan ectopterygoid from the Upper Cretaceous (lower Cenomanian) Bahariya Formation of the Bahariya Oasis, Egypt, is nearly identical to the holotypic specimen of Polypterus? bartheli from the same area and geologic unit. The Bahariya ectopterygoids are referable to Polypteridae based on the presence of a robust, laterally directed process that articulates with the maxilla. Additionally, ganoid scales from the Bahariya Formation have an isopedine layer, a histological character of Polypteriformes; but differ from those of previously described members of this clade in having a discontinuous ganoin layer, rectilinear shape, and proportionally small articular processes. Both the ectopterygoids and the scales are unusually large, and are the only polypteriform remains so far identified from the Bahariya Formation. The ectopterygoids and (tentatively) the scales are herein assigned to a single species of gigantic polypterid, the morphology of which is sufficiently distinctive to warrant its placement in a new genus, Bawitius, gen. nov. Differences in scale anatomy and the enormous disparity in body size between Bawitius and Serenoichthys support the hypothesis (originally proposed on the basis of varied fin spine morphologies) that a diversity of polypterid fishes inhabited North Africa during the early Late Cretaceous.
Research Interests:
A new genus of crab from the Late Cretaceous of Antarctica increases diversity within Necrocarcinidae Förster, 1968, and demonstrates what appear to be gradual evolution and sympatric speciation in the southern high latitudes. New taxa... more
A new genus of crab from the Late Cretaceous of Antarctica increases diversity within Necrocarcinidae Förster, 1968, and demonstrates what appear to be gradual evolution and sympatric speciation in the southern high latitudes. New taxa include Hadrocarcinus tectilacus, new genus, new species, as well as two new combinations, Hadrocarcinus carinatus (Feldmann et al., 1993) and Hadrocarcinus wrighti (Feldmann et al., 1993). Necrocarcinidae was paleogeographically widespread by the middle Early Cretaceous, but the geographic distribution and diversity of the group increased even further by the middle Late Cretaceous, perhaps as a result of high sea levels and elevated global temperatures at that time. The paleogeographic range and diversity of necrocarcinids decreased during the latest Cretaceous and into the earliest Paleocene (Danian), possibly due to decreases in sea level and global temperatures, restricting the family to the northern high latitudes. Alternatively, apparent diversity trends in Necrocarcinidae may simply reflect available rock volume.
Research Interests:
Brachyuran decapods (crabs) are rarely preserved in coastal environments and have not been documented in close association with dinosaur fossils. A crab referable to the Necrocarcinidae Forster, 1968, is here described from the Cenomanian... more
Brachyuran decapods (crabs) are rarely preserved in coastal environments and have not been documented in close association with dinosaur fossils. A crab referable to the Necrocarcinidae Forster, 1968, is here described from the Cenomanian Bahariya Formation, Bahariya Oasis, Egypt. The occurrence of a crab in a mangrove setting in association with terrestrial vertebrates is extremely unusual in the fossil record. Review of decapod occurrences from the region has resulted in placement of Portunus sp. of Roger (1946) within the Raninidae de Haan, 1839, and Lophoraninella cretacea (Dames, 1886) into the Galatheoidea Samouelle, 1819. The crabs of the Bahariya Formation were probably scavengers, feeding on vegetation and other organic material and were possibly a food source for fish and other vertebrates and invertebrates in the environment.