Raymond R Rogers

Raymond R Rogers
Macalester College · Department of Geology

PhD, University of Chicago

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105
Publications
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3,814
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January 2003 - December 2010

Publications

Publications (105)
Article
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The spectacular fossil fauna and flora preserved in the Upper Cretaceous terrestrial strata of North America’s Western Interior Basin record an exceptional peak in the diversification of fossil vertebrates in the Campanian, which has been termed the ‘zenith of dinosaur diversity’. The wide latitudinal distribution of rocks and fossils that represen...
Article
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Mesozoic birds display considerable diversity in size, flight adaptations and feather organization1–4, but exhibit relatively conserved patterns of beak shape and development5–7. Although Neornithine (that is, crown group) birds also exhibit constraint on facial development8,9, they have comparatively diverse beak morphologies associated with a ran...
Article
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Adalatherium hui is a latest Cretaceous (Maastrichtian) gondwanatherian mammal based on only a single specimen, a virtually complete, articulated, and well-preserved skull and postcranial skeleton. The specimen is the most complete and best preserved of any mammaliaform from the Mesozoic of the southern supercontinent Gondwana. It was discovered in...
Article
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The fossil record of mammaliaforms (mammals and their closest relatives) of the Mesozoic era from the southern supercontinent Gondwana is far less extensive than that from its northern counterpart, Laurasia1,2. Among Mesozoic mammaliaforms, Gondwanatheria is one of the most poorly known clades, previously represented by only a single cranium and is...
Article
Previous studies have yielded mixed results as to whether authigenic mineral infill in fossilized bone tracks specific lithologies or depositional environments, with most suggesting weak to no correlation between infill composition and host lithofacies. This study documents infill patterns in a suite of fossil bones from the Upper Cretaceous Two Me...
Conference Paper
We demonstrate an integrated methodology for using CT in both mechanical and digital preparation of field jackets collected from locality MAD 05-42 in Upper Cretaceous deposits of the Maevarano Formation, Mahajanga Basin, Madagascar. Following in-quarry surface mapping, field jackets were documented in a medical CT scanner before mechanical prepara...
Article
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The Mesozoic plate tectonic and paleogeographic history of Gondwana had a profound effect on the distribution of terrestrial vertebrates. As the supercontinent fragmented into a series of large landmasses (South America, Africa-Arabia, Antarctica, Australia, New Zealand, the Indian subcontinent, and Madagascar), particularly during the Late Jurassi...
Article
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Vertebrate microfossil bonebeds (VMBs)—localized concentrations of small resilient vertebrate hard parts—are commonly studied to recover otherwise rarely found small-bodied taxa, and to document relative taxonomic abundance and species richness in ancient vertebrate communities. Analyses of taphonomic comparability among VMBs have often found signi...
Article
Despite longstanding significance in the annals of North American stratigraphy and paleontology, key aspects of the Upper Cretaceous Judith River Formation remain poorly understood. We re-evaluate Judith River stratigraphy and propose new reference sections that both document the range of lithologies present in the type area in north-central Montan...
Poster
Fossil vertebrates from the Gokwe Formation (Fm) of central Zimbabwe have been known for over 50 years, yet remain poorly understood due in part to their poor preservation and the uncertainty surrounding their age, previously constrained to Upper Jurassic-Cretaceous. Collections from the Gokwe Fm include a diverse array of vertebrate fossils that b...
Article
ABSTRACT—Vintana sertichi is a sudamericid gondwanatherian mammal known only from the Upper Cretaceous (Maastrichtian) Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. It is based on a single specimen, a well-preserved and virtually complete cranium discovered in 2010 near Lac Kinkony. The cranium is superficially bizarre and...
Article
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Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous and Palaeogene of the Southern Hemisphere, the Gondwanatheria constitute the most poorly known of all major mammaliaform radiations. Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium from...
Conference Paper
Full-text available
Permineralization of vertebrate fossils is typically a story of calcite and Fe-rich mineral paragenesis. Detailed study with a focus on a broad range of minerals using scanning electron microscope (SEM) has revealed a more complex history of diagenesis related to paleoclimate and tectonics. Eight paleovertebrate assemblages from the Ischigualasto a...
Article
The case was cold, but critical clues pointed to a killer's identity in ancient Madagascar
Article
Full-text available
Trends of preservation are established on the basis of 385 fossil occurrences in the Ischigualasto Formation. The distribution and preservational quality of vertebrate fossils are related to sedimentary facies and stratigraphic position and follow trends in basin evolution and paleoclimate. Fossils in the Ischigualasto Formation are mainly concentr...
Article
A new member of the Upper Cretaceous (Maastrichtian) Maevarano Formation is proposed to accommodate a distinctive succession of strata exposed along the shores of Lac Kinkony in northwestern Madagascar. The new Lac Kinkony Member overlies fully terrestrial sandstones of the Anembalemba Member of the Maevarano Formation, and is capped by marine dolo...
Article
Full-text available
A new member of the Upper Cretaceous (Maastrichtian) Maevarano Formation is proposed to accommodate a distinctive succession of strata exposed along the shores of Lac Kinkony in northwestern Madagascar. The new Lac Kinkony Member overlies fully terrestrial sandstones of the Anembalemba Member of the Maevarano Formation, and is capped by marine dolo...
Article
An assemblage of large-diameter vertical burrows interpreted as lungfish estivation burrows is documented from the Upper Cretaceous (Maastrichtian) Maevarano Formation of northwestern Madagascar. These burrows suggest that lungfish were present in the Maevarano Formation paleofauna, and they are the first lungfish estivation burrows described from...
Article
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Osteoderms are bones embedded within the dermis, and are common to select members of most major tetrapod lineages. The largest known animals that bear osteoderms are members of Titanosauria, a diverse clade of sauropod dinosaurs. Here we report on two titanosaur osteoderms recovered from the Upper Cretaceous Maevarano Formation of Madagascar. Each...
Poster
Recent field efforts conducted as part of the Mahajanga Basin Project have resulted in a significantly improved sampling of theropod dinosaurs from the Maevarano Formation. Both avialan and nonavialan taxa have been recovered from MAD 05-42, a locality exhibiting a mixed taphonomic signature that includes a range of preservational styles. Small (<...
Article
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Robust isotopic reconstructions of climate, elevation, and biology require a reasonable capture of the range of isotopic variability across a paleolandscape. Here, we illustrate how integrating multiple proxies derived from a variety of paleoenvironments aids in this effort. We determined δ¹ɸO and δ¹³C values from lake and soil carbonates, unionid...
Article
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Phanerozoic trends in shell and life habit traits linked to postmortem durability were evaluated for the most common fossil brachiopod, gastropod, and bivalve genera in order to test for changes in taphonomic bias. Using the Paleobiology Database, we tabulated occurrence frequencies of genera for 48 intervals of ∼11 Myr duration. The most frequentl...
Article
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Microfossil bonebeds are multi-individual accumulations of disarticulated and dissociated vertebrate hardparts dominated by elements in the millimeter to centimeter size range (>75% of bioclasts <5 cm maximum dimension). Modes of accumulation are often difficult to decipher from reports in the literature, although predatory (scatological) and fluvi...
Article
Simosuchus clarki is a bizarre, pug-nosed notosuchian crocodyliform known only from the Upper Cretaceous (Maastrichtian) Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. When originally named and described in 2000, S. clarki was based entirely on a single specimen that included a nearly complete skull and lower jaw preserved i...
Article
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Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) was used to determine rare earth element (REE) content of 76 fossil bones collected from the Upper Cretaceous (Campanian) Two Medicine (TMF) and Judith River (JRF) Formations of Montana. REE content is distinctive at the formation scale, with TMF samples exhibiting generally hig...
Article
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The first diagnostic sirenian material from Madagascar and, more broadly, the first diagnostic pre-Pleistocene Cenozoic mammal material recovered from the island is reported. Eotheroides lambondrano is a new species of sirenian collected from middle Eocene nearshore marine deposits in the Mahajanga Basin of northwestern Madagascar. The recovered ma...
Article
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Elemental maps generated by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) provide a previously unavailable high-resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization. A selection of LA-ICP-MS maps of bones collected from...
Article
Mechanical properties of the pigeon humerus are significantly influenced by internal bony trabeculae. Experimental testing of braced (intact trabeculae) and unbraced (trabeculae experimentally removed) humerus pairs extracted from the same individuals demonstrates that the flexural rigidity, strength and toughness (work of fracture) of the pigeon h...
Article
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Stable carbon and oxygen isotope ratios were measured for carbonate in samples of hadrosaurid tooth enamel and dentine, and gar scale ganoine and dentine from five geologically “contemporaneous“ (two-million-year resolution) and geographically distant late Campanian formations (Two Medicine, Dinosaur Park, Judith River, Kaiparowits, and Fruitland)...
Article
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The abelisaurid theropod Majungasaurus crenatissimus inhabited the plains of northwestern Madagascar during the Late Cretaceous. It lived alongside other nonavian dinosaurs, including a small-bodied noasaurid theropod (Masiakasaurus knopfleri) and a titanosaurian sauropod (Rapetosaurus krausei). Although an inhabitant of the expansive floodplains o...
Article
The Mahajanga Basin Project, initiated in 1993 and centered in Upper Cretaceous strata of northwestern Madagascar, has resulted in the discovery of some of the most complete, well-preserved, and significant specimens of Late Cretaceous vertebrate animals from the Southern Hemisphere and indeed the world. Among the most important finds are various s...
Article
Although the use of stable isotope data from vertebrate remains is becoming common for the Cenozoic, their application to Mesozoic environments has been rare, in part due to the perception that diagenesis has obfuscated all potential primary signal. In this paper, we illustrate how stable isotope data collected from dinosaur and other vertebrate re...
Article
Terrestrial deposits of the Upper Cretaceous (Campanian) Two Medicine Formation of northwestern Montana preserve multiple bentonite beds (n ≥ 19) that reflect recurrent pyroclastic events in the Western Interior Basin. Major and trace element concentrations were determined on 27 samples derived from four bentonites using X-ray fluorescence spectros...
Article
Preservation of intact macromolecules and geochemical signals in fossil bones is mainly controlled by the extent of post-mortem interaction between bones and sediment pore waters. Trace elements such as lanthanum are added to bone post-mortem from pore waters, and where uptake occurs via a simple process of diffusion and adsorption, the elemental d...
Article
Twenty three different sites in two areas of Río Negro Province (Salitral Ojo de Agua and Salitral de Santa Rosa-Salinas de Trapalcó), preserving eggs and eggshells from the Allen Formation (Upper Cretaceous) were studied, and five egg levels were identified. Three different types of eggshell were recognized. Eggs possessing thick eggshells of Type...
Article
Large meat-eating dinosaur Majungatholusatopus (above) met an untimely end some 70 million years ago in what is now northwestern Madagascar (opposite page, top]. Members of the authors' team carefully excavated the remains, including a jaw with serrated teeth used to slice through flesh (right), and packed them in plaster for transport to the U.S....
Article
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Two new insect-related ichnogenera are reported in fossil dinosaur bones from Upper Cretaceous continental strata in Madagascar and Utah. Cubiculum ornatus n. igen. and isp. is described from numerous fossil bones in the Upper Cretaceous Maevarano Formation of northwestern Madagascar, and consists of hollow, ovoid chambers with concave flanks excav...
Article
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Two new insect-related ichnogenera are reported in fossil dinosaur bones from Upper Cretaceous continental strata in Madagascar and Utah. Cubiculum ornatus n. igen. and isp. is described from numerous fossil bones in the Upper Cretaceous Maevarano Formation of northwestern Madagascar, and consists of hollow. ovoid chambers with concave flanks excav...
Article
The vertebrate fossil record extends back more than 500 million years, and bonebeds—localized concentrations of the skeletal remains of vertebrate animals—help unlock the secrets of this long history. Often spectacularly preserved, bonebeds—both modern and ancient—can reveal more about life histories, ecological associations, and preservati...
Article
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The origin of Madagascar’s highly endemic vertebrate fauna remains one of the great unsolved mysteries of natural history. From what landmasses did the basal stocks of this unique and imbalanced fauna come? When and how did the ancestral populations arrive on the island? How rapidly did they diversify, and why? The most direct means of addressing t...
Article
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The present paper includes detailed descriptions of all fossil fishes known from the Los Rastros Formation (Ladinian; Bermejo Basin, Argentina). Four taxa are identified: Gualolepis carinaesquamosa n. gen. n. sp., Rastrolepis n. gen. with two species R . riojaensis n. sp. and R . latipinnata n. sp., and Challaiaelongata n. comb. Gualolepis n. gen....
Article
Full-text available
The present paper includes detailed descriptions of all fossil fishes known from the Los Rastros Formation (Ladinian; Bermejo Basin, Argentina). Four taxa are identified: Gualolepis carinaesquamosa n. gen. n. sp., Rastrolepis n. gen. with two species R . riojaensis n. sp. and R. latipinnata n. sp., and Challaiaelongata n. comb. Gualolepis n. gen. a...
Article
Full-text available
This paper tests whether the most common fossil brachiopod, gastropod, and bivalve genera also have intrinsically more durable shells. Commonness was quantified using occurrence frequency of the 450 most frequently occurring genera of these groups in the Paleobiology Database (PBDB). Durability was scored for each taxon on the basis of shell size,...
Article
Full-text available
Vertebrate fossils are remarkably abundant and exceptionally well preserved within the Upper Cretaceous Maevarano Formation of northwestern Madagascar. The vast majority of these fossils, including all of the currently known bone beds, are entombed within deposits of fine-grained cohesive debris flows. These deposits are typically massive and are c...
Article
Karoo-equivalent rocks in the Tuli Basin of Zimbabwe are described, with a focus on the dinosaur-bearing Mpandi Formation, which correlates with the Elliot Formation (Late Triassic–Early Jurassic) in the main Karoo Basin. Isolated exposures of the Mpandi Formation along the banks of the Limpopo River consist of red silty claystones and siltstones t...
Article
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Many lines of evidence have been brought to bear on the question of theropod feeding ecology, including functional and physiological considerations, morphological constraints, taphonomic associations, and telling--although rare--indications of direct ingestion. Tooth marks of theropods, although rarely described and generally left unassigned to a p...
Article
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The enigmatic concretionary exposures that typify the Chahares Formation (Ladinian, northwestern Argentina) long have defied precise paleoenvironmental characterization. Recent work indicates that the formation accumulated in an alluvial-to-lacustrine setting within an active rift basin that received sedimentary detritus from surrounding highlands,...
Article
Full-text available
Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. W...
Article
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Although lags of bones and teeth are commonly cited criteria for marine unconformities, the consistency of the association of vertebrate fossils and discontinuity surfaces, as well as the taphonomic (postmortem) controls on this relationship, are poorly understood. A field test across fluvial, paralic, and shallow marine facies in the Campanian Two...
Article
Oxygen isotope ratios of fossil remains of coexisting taxa from several different localities can be used to help investigate dinosaur thermoregulation. Focusing on the Late Cretaceous, oxygen isotope ratios of crocodile tooth enamel from four separate localities exhibit less of a decrease with latitude than do ratios of tooth enamel from coexisting...