Papers by David A Burnham
Paläontologische Zeitschrift, 2010
Palaeoworld, 2012
Herein we describe a new species of Microraptor from northeastern China that provides new informa... more Herein we describe a new species of Microraptor from northeastern China that provides new information on the characteristics of the genus and anatomical details suggesting a gliding behaviour. Although specimens of Microraptor have been known for at least a decade, the completeness of the new fossil provides additional morphology that highlights the uniqueness of this taxon. The new specimen, Microraptor hanqingi, is the key to understanding the evolutionary significance of hindlimb wings. A four-winged structure present on an organism sharing an evolutionary lineage leading to modern birds implies that gliding was a stage in the development of avian flight. M. hanqingi represents the largest known microraptorian from China with a total length of approximately 1 m, and was closely-related to the venomous form, Sinornithosaurus.
Fig. 7. The Tanis Konservat-Lagerstätte. (A) Plaster field jacket with partially prepared (freshw... more Fig. 7. The Tanis Konservat-Lagerstätte. (A) Plaster field jacket with partially prepared (freshwater) acipenseriform fish (FAU.DGS.ND.161.116.T) next to a nacreous ammonite shell (Inset). (B) Partial site map showing carcasses oriented by flow. (c) Field photo showing mass grave of fish carcasses,aligned by flow.
Fig. 6. Acipenseriform fish with ejecta clustered in the gill region. (A) X-ray of a fossil sturg... more Fig. 6. Acipenseriform fish with ejecta clustered in the gill region. (A) X-ray of a fossil sturgeon head (outlined, pointing left; FAU.DGS.ND.161.115.T). (B) Magnified image of the X-ray in A showing numerous ejecta spherules clustered within the gill region (arrows). (c and D) Micro-CT images of another fish specimen (paddlefish; FAU.DGS.ND.161.29.T), with microtektites embedded between the gill rakers in the same fashion.
Fig. 4. In situ ejecta at Tanis. (A–c) Field photos of an ejecta lens in situ. (D) Petrographic t... more Fig. 4. In situ ejecta at Tanis. (A–c) Field photos of an ejecta lens in situ. (D) Petrographic thin section of a spherule lens (FAU.DGS.ND.161.88.T). (E) Crosssection of down-warped "microcrater" caused by incoming ejecta, with arrow pointing to spherule (FAU.DGS.ND.161.65.T). (Right) Region of origin for the items pictured.
Fig. 3. Chicxulub tonstein capping the Event Deposit at Tanis and representative impact-derived m... more Fig. 3. Chicxulub tonstein capping the Event Deposit at Tanis and representative impact-derived materials. (A) Iridium-enriched tonstein in situ atop the Event Deposit. (B) Shocked mineral with multiple intersecting planar deformation features (FAU.DGS.ND.161.977.T). (c) Clay-altered ejecta spherules (FAU.DGS.ND.161.33.T), some with prominent schlieren. (D) Micro-CT of a clay-altered ejecta spherule with unaltered glass core (FAU.DGS.ND.161.11.T). (E) Shards of unaltered impact glass (FAU.DGS.ND.161.45.T).
Fig. 2. Tanis site stratigraphy and fossil distribution. Stratigraphic section of Tanis, outlinin... more Fig. 2. Tanis site stratigraphy and fossil distribution. Stratigraphic section of Tanis, outlining the lithological subdivisions and grain-size profile for the Event Deposit, abundance and primary stratigraphic distribution for a selection of continental and marine fossils, abundance of marine palynomorphs (palyno %), select impact-derived materials, and flow direction.
Fig. 1. Map of the Tanis study locality. (A) Tanis within a regional context (large map) and on a... more Fig. 1. Map of the Tanis study locality. (A) Tanis within a regional context (large map) and on a national map (Inset). Reprinted with permission from ref. 14; black dots in Inset are previously documented KPg tsunami localities; star denotes Tanis. Kf, Fox Hills Formation; Kh, Hell Creek Formation; Kp, Pierre Shale; Qor, Holocene; QTu, Quaternary and Upper Tertiary; Tp, Slope Formation. (B) Photo and interpretive overlay of an oblique cross-section through Tanis, showing the contact between the angled point-bar sandstone and the gray Hell Creek bedrock.(c) Simplified schematic depicting the general contemporaneous depositional setting for the Event Deposit (not to scale). The Event Deposit (1) covers the slope of a prograding point bar of a meander (2), which incised into the Hell Creek bedrock during the late Cretaceous. Location of the densest carcass accumulations (3) along the slope; location of KPg boundary tonstein directly overlying the Event Deposit (4); location of KPg ton...
Two coalesced hadrosaur (compare with<i> Edmontosaurus annectens</i>) caudal vertebra... more Two coalesced hadrosaur (compare with<i> Edmontosaurus annectens</i>) caudal vertebrae were discovered in the Hell Creek Formation of Harding County, South Dakota ( 40). Archosaur fauna identified in this site include crocodiles, dinosaurs, and birds ( 41). Physical evidence of dental penetration and extensive infection (osteomylitis) of the fused vertebral centra and healing (bone overgrowth) document an unsuccessful attack by a large predator. A tooth crown was discovered within the wound, permitting identification of the predator as<i> T. rex</i>. This is unambiguous evidence that<i> T. rex</i> was an active predator, fulfilling the criteria that Farlow and Holtz ( 3) advanced. As<i> T. rex</i> comprises between 1% and 16% of the Upper Cretaceous dinosaurian fauna in Western North America ( 41 – 45), its status as a predator or obligate scavenger is nontrivial and could have significant implications for paleoecological reconstructio...
Fig. 3. Lateral view of embedded tooth crown showing well-developed blood grooves oriented obliqu... more Fig. 3. Lateral view of embedded tooth crown showing well-developed blood grooves oriented obliquely toward the base and large, chisel-shaped mesial denticles typical of T. rex (60); (Scale bar: 5 mm.)
Fig. 2. CT scans of the fused hadrosaur vertebrae, showing embedded theropod tooth and reactive b... more Fig. 2. CT scans of the fused hadrosaur vertebrae, showing embedded theropod tooth and reactive bone (A–c). Longitudinal slice through the fused vertebrae shows the substantial overgrowth of reactive bone on the outside of the centra, while the articular surfaces remain largely unaffected (A). Two oblique slices through the vertebrae show the embedded theropod tooth in cross-section and the reactive bone that partially surrounds it (B and c). (Scale bars: A, 20 mm and B and c, 10 mm.)
Fig. 1. Depiction of a hadrosaur skeleton showing the position in the tail of the fused vertebrae... more Fig. 1. Depiction of a hadrosaur skeleton showing the position in the tail of the fused vertebrae (A) and a lateral view of the affected vertebrae with the circle indicating the location of the theropod tooth (B).
Geological Society of America Abstracts with Programs, 2017
Scientific Reports, 2021
The end-Cretaceous Chicxulub impact triggered Earth’s last mass-extinction, extinguishing ~ 75% o... more The end-Cretaceous Chicxulub impact triggered Earth’s last mass-extinction, extinguishing ~ 75% of species diversity and facilitating a global ecological shift to mammal-dominated biomes. Temporal details of the impact event on a fine scale (hour-to-day), important to understanding the early trajectory of mass-extinction, have largely eluded previous studies. This study employs histological and histo-isotopic analyses of fossil fish that were coeval with a unique impact-triggered mass-death assemblage from the Cretaceous-Paleogene (KPg) boundary in North Dakota (USA). Patterns of growth history, including periodicity of ẟ18O and ẟ13C and growth band morphology, plus corroborating data from fish ontogeny and seasonal insect behavior, reveal that the impact occurred during boreal Spring/Summer, shortly after the spawning season for fish and most continental taxa. The severity and taxonomic symmetry of response to global natural hazards are influenced by the season during which they oc...
Geological Society of America Abstracts with Programs, 2021
Geological Society of America Abstracts with Programs, 2021
PeerJ, 2018
A set of associated left pedal elements of a sauropod dinosaur from the Upper Jurassic Morrison F... more A set of associated left pedal elements of a sauropod dinosaur from the Upper Jurassic Morrison Formation in Weston County, Wyoming, is described here. Several camarasaurids, a nearly complete small brachiosaur, and a small diplodocid have been found at this locality, but none match the exceptionally large size of the pedal elements. Next to the associated pedal elements, an isolated astragalus, phalanx and ungual were found, which match the large metatarsals in size. The elements cannot be ascribed to diplodocids due to the lack of a ventral process of metatarsal I. Moreover, the morphology of metatarsal V has a broad proximal end, with a long and narrow distal shaft, which differs fromCamarasaurus. The size of the material and a medially beveled distal articular surface of metatarsal IV imply an identification as a brachiosaurid. This is the largest pes ever reported from a sauropod dinosaur and represents the first confirmed pedal brachiosaur elements from the Late Jurassic of No...
Proceedings of the National Academy of Sciences, 2019
Significance The Chicxulub impact played a crucial role in the Cretaceous–Paleogene extinction. H... more Significance The Chicxulub impact played a crucial role in the Cretaceous–Paleogene extinction. However the earliest postimpact effects, critical to fully decode the profound influence on Earth’s biota, are poorly understood due to a lack of high-temporal-resolution contemporaneous deposits. The Tanis site, which preserves a rapidly deposited, ejecta-bearing bed in the Hell Creek Formation, helps to resolve that long-standing deficit. Emplaced immediately (minutes to hours) after impact, Tanis provides a postimpact “snapshot,” including ejecta accretion and faunal mass death, advancing our understanding of the immediate effects of the Chicxulub impact. Moreover, we demonstrate that the depositional event, calculated to have coincided with the arrival of seismic waves from Chicxulub, likely resulted from a seismically coupled local seiche.
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Papers by David A Burnham