Matthew T Carrano

Smithsonian Institution · Department of Paleobiology

In the 1960s, United States Geological Survey (USGS) geologists working in the Late Cretaceous (Maastrichtian) Harebell Formation in the Big Game Ridge area of Yellowstone National Park, Wyoming, collected the first known dinosaur fossil from this iconic park. Consisting of a single shed theropod tooth, the fossil was previously identified as a “de...

We describe a new, small-bodied rhynchocephalian reptile, Opisthiamimus gregori gen. et sp. nov., from the Upper Jurassic Morrison Formation of Wyoming, USA. Whereas many fossil rhynchocephalians are based on isolated incomplete jaws, the holotype of O. gregori includes most of the skull and postcranium and therefore represents one of the most comp...

We describe a new species of the albanerpetontid amphibian Albanerpeton from three localities in the Lower Cretaceous Cloverly Formation of Wyoming, U.S.A. Radiometric dates between ∼111–112 Ma indicate it is slightly younger than A. arthridion from the Antlers Formation. The new species is diagnosed on a pair of fused frontals that possess a uniqu...

Dinosaurs dominated Mesozoic terrestrial ecosystems globally. However, whereas a pole-to-pole geographic distribution characterized ornithischians and theropods, sauropods were restricted to lower latitudes. Here, we evaluate the role of climate in shaping these biogeographic patterns through the Jurassic–Cretaceous (201–66 mya), combining dinosaur...

As the fossil record of injuries and/or diseases, paleopathologies are one of the most direct insights into dinosaur paleobiology. In spite of the vagaries of vertebrate fossil taphonomy and the restriction that diseases must be recorded on hard parts, there are more than 400 reports of paleopathological dinosaur body fossils in the peer-reviewed l...

Phytosaurs were a widespread clade of Triassic predatory archosauriforms whose skull anatomy is well known, but whose paleobiology is underexplored. Here we report on a well-preserved specimen from Adamanian (early-mid-Norian) strata in Arizona that includes not only the skull and lower jaws but much of the postcranial skeleton, which exhibits exte...

There is no consensus about how terrestrial biodiversity was assembled through deep time, and in particular whether it has risen exponentially over the Phanerozoic. Using a database of 60 859 fossil occurrences, we show that the spatial extent of the worldwide terrestrial tetrapod fossil record itself expands exponentially through the Phanerozoic....

Like many long‐standing dinosaur taxa, Brachiosaurus altithorax from the Upper Jurassic Morrison Formation of North America suffers from taxonomic issues stemming from a relatively incomplete holotype. Lack of anatomical overlap has precluded definitive referral of important specimens, including a mostly complete skull discovered in 1883. We redesc...

The fossil record provides one of the strongest tests of the hypothesis that diversity within local communities is constrained over geological timescales. Constraints to diversity are particularly controversial in modern terrestrial ecosystems, yet long-term patterns are poorly understood. Here we document patterns of local richness in Phanerozoic...

Vertebrate microfossil assemblages in a stratigraphic sequence often yield similar assortments of taxa but at different relative abundances, potentially indicative of marginal paleocommunity changes driven by paleoenvironmental change over time. For example, stratigraphically younger assemblages in the Dinosaur Park Formation (DPF) yield proportion...

Multituberculata, with the longest evolutionary history of any mammalian clade, represents an ideal group for studying the evolution of feeding ecology within non-therian mammals. Recent studies have challenged the historical view of non-therian mammals as primarily terrestrial generalists that fed on insects. Indeed, non-therian mammals show great...

The largest known dinosaurs weighed at least 20 million times as much as the smallest, indicating exceptional phenotypic divergence. Previous studies have focused on extreme giant sizes, tests of Cope's rule, and miniaturization on the line leading to birds. We use non-uniform macroevolutionary models based on Ornstein–Uhlenbeck and trend processes...

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...

Until now, only one Cenozoic fossil mammal from the Chilean Precordillera (Arica and Parinacota Region) has been reported, Caraguatypotherium munozi (Mesotheriidae: Notoungulata). In this study, we describe a fourth specimen of C. munozi and a new armadillo species, Epipeltephilus caraguensis (Peltephilidae: Cingulata), both collected from a new si...

Theropod dinosaurs from the Late Jurassic of Gondwana are still poorly known, with Elaphrosaurus bambergi Janensch, 1920, from the late Kimmeridgian of Tendaguru, Tanzania, being the only taxon represented by more than isolated remains from Africa. Having long been considered a coelurosaurian, more specifically an ornithomimosaur, Elaphrosaurus is...

In their recent publication on an overview of theropod discoveries and classification, Hendrickx and colleagues mistakenly attributed the earliest historical reports of nonavian theropods in North America and South America to Joseph Leidy in 1856 and Florentino Ameghino in 1899, respectively. Yet, theropod tracks from Massachusetts had already been...

How did evolution generate the extraordinary diversity of vertebrates on land? Zero species are known prior to ~380 million years ago, and more than 30,000 are present today. An expansionist model suggests this was achieved by large and unbounded increases, leading to substantially greater diversity in the present than at any time in the geological...

Here we describe the forearm and manus of the ceratosaurian theropod dinosaur Ceratosaurus nasicornis Marsh, 1884, from the Upper Jurassic Morrison Formation of the western U.S.A. Recently removed from exhibition and reprepared, the holotype offers important new information on the morphology of this taxon that bears on the evolution of the forelimb...

Vertebrate microfossil assemblages in terrestrial formations are a promising source of data on the structure of fossil metacommunities. However, the degree to which these deposits capture true, metacommunity-level samples is unknown. Individual deposits may be biased in ways that limit their utility for intra- and inter-formation comparisons. This...

Subsampled genus diversity within continental regions for a quorum of 0.4. (A) Results for all tetrapods; the dashed line is the general linear model predicting subsampled regional genus diversity from geological age for the entire Mesozoic, modelling taxon counts as a Gaussian distribution and using a ln() link function (slope = -0.003; standard e...

Countries included in our contiguous continental regions. (DOCX)

Histograms of global minimum spanning tree branch lengths (in km) for the ten intervals with the longest minimum spanning trees. Interval name abbreviations are given in S1 Table. Red dashed lines indicate 100 km and 1,000 km. The data displayed in this figure can be accessed at http://doi.org/10.5061/dryad.9fr76 [90]. (TIF)

Additional methods and results. Justification of the continental regions used and subsampled genus diversity. (DOCX)

Composite 9 Myr time bins used in the present study. Pg2 ends at 48.6 Ma. Occurrences were assigned to a time bin only if their stratigraphic age uncertainty was entirely contained within that bin. (DOCX)

Reed’s Quarry 9 at Como Bluff in Albany County, Wyoming has yielded the most diverse, well studied microvertebrate fauna from the Upper Jurassic Morrison Formation. Discovered in 1879 by W. H. Reed during his time prospecting and collecting fossils for O. C. Marsh, it was worked by Reed and others for nearly 10 years before it seemed to be exhauste...

The fossil record of crocodylians and their relatives (pseudosuchians) reveals a rich evolutionary history, prompting questions about causes of long-term decline to their present-day low biodiversity. We analyse climatic drivers of subsampled pseudosuchian biodiversity over their 250 million year history, using a comprehensive new data set. Biodive...

Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone strain magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level strain magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that os...

Fossils provide the principal basis for temporal calibrations, which are critical to the accuracy of divergence dating analyses. Translating fossil data into minimum and maximum bounds for calibrations is the most important, and often least appreciated, step of divergence dating. Properly justified calibrations require the synthesis of phylogenetic...

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP; CT data are available as Morphobank project P2093 at http://www.morphobank.org.

The broad palette of feather colours displayed by birds serves diverse biological functions, including communication and camouflage. Fossil feathers provide evidence that some avian colours, like black and brown melanins, have existed for at least 160 million years (Myr), but no traces of bright carotenoid pigments in ancient feathers have been rep...

Body mass is strongly related to both physiological and ecological properties of living organisms. As a result, generating robust, broadly applicable models for estimating body mass in the fossil record provides the opportunity to reconstruct palaeobiology and investigate evolutionary ecology on a large temporal scale. A recent study provided stron...

Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over...

Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time...

The ‘Kem Kem beds’ of Morocco have yielded abundant material of largebodied theropod dinosaurs, but remains of small theropod taxa are rare. Here, we describe two femora that provide additional information on the diversity of small-bodied theropods in the Gondwanan mid-Cretaceous. An almost complete femur (ROM 64666) represents a noasaurid theropod...

We describe an unusual squamate fossil from the Green River Formation (Uintan, Eocene) from the Piceance Creek Basin, Colorado, USA. The new specimen, USNM PAL 540708, is a small fossil squamate skin lacking skeletal elements. It is preserved as a part and counterpart in fine-grained limestone. Recovery of a fossil organism's skin (not a shed, but...

The vertebrate fauna of the Cloverly Formation has been studied for more than 75 years, but remains poorly sampled and incompletely understood. We undertook an extensive survey of the formation that resulted in the discovery of several new, highly productive vertebrate microfossil bonebeds (VMBs). Comprehensive sampling of these and other sites has...

Data, whether images, measurements, counts, occurrences, or character codings, are a cornerstone of vertebrate paleontology. Every published paper,master’s thesis, and doctoral dissertation relies on these data to document patterns and processes in evolution, ecology, taphonomy, geography, geologic time, and functional morphology, to name just a fe...

Aim Modern biodiversity peaks in the tropics and declines poleward, a pattern that is potentially driven by climate. Although this latitudinal biodiversity gradient (LBG) also characterizes the marine invertebrate fossil record, distributions of ancient terrestrial faunas are poorly understood. This study utilizes data on the dinosaur fossil record...

Tetanuran theropods represent the majority of Mesozoic predatory dinosaur diversity and the lineage leading to extant Aves. Thus their history is relevant to understanding the evolution of dinosaur diversity, Mesozoic terrestrial ecosystems, and modern birds. Previously, the fragmentary and poorly sampled fossil record of basal (non-coelurosaur) te...

The basal theropod dinosaur clade Ceratosauria, and its subclade Abelisauroidea, is characteristic of late Mesozoic terrestrial vertebrate faunas in western Gondwana (South America, Africa, Madagascar, and India) and Europe. Yet unambiguous records of ceratosaurs have hitherto been absent from Australia, where the theropod assemblage appears to inc...

Abelisaurid theropods are common members of Cretaceous Gondwanan faunas and are characterized by a bizarre, highly reduced forelimb. Unfortunately, forelimb elements are rarely preserved and thus the basic structure of the abelisaurid forelimb remains poorly understood. Until recently, the Upper Cretaceous Maevarano Formation of northwestern Madaga...

Schmitz and Motani (Reports, 6 May 2011, p. 705) claimed to definitively reconstruct activity patterns of Mesozoic archosaurs using the anatomy of the orbit and scleral ring. However, we find serious flaws in the data, methods, and interpretations of this study. Accordingly, it is not yet possible to reconstruct the activity patterns of most fossil...

Dinosaurs provide excellent opportunities to examine the impact of sampling biases on the palaeodiversity of terrestrial organisms. The stratigraphical and geographical ranges of 847 dinosaurian species are analysed for palaeodiversity patterns and compared to several sampling metrics. The observed diversity of dinosaurs, Theropoda, Sauropodomorpha...

  The Cretaceous dinosaur fauna of Indo-Pakistan has remained poorly understood because of a lack of associated and articulated remains, proliferation of named species, and an incomplete understanding of the dinosaur clades present (e.g. abelisaurid theropods; titanosaur sauropods). Continued work on existing collections, and new discoveries of din...

Pneumatic (air-filled) postcranial bones are unique to birds among extant tetrapods. Unambiguous skeletal correlates of postcranial pneumaticity first appeared in the Late Triassic (approximately 210 million years ago), when they evolved independently in several groups of bird-line archosaurs (ornithodirans). These include the theropod dinosaurs (o...

Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3-6 March, 2011, Durham, NC, USA), bringing t...

The accurate reconstruction of palaeobiodiversity patterns is central to a detailed understanding of the macroevolutionary history of a group of organisms. However, there is increasing evidence that diversity patterns observed directly from the fossil record are strongly influenced by fluctuations in the quality of our sampling of the rock record;...

Osteology of the noasaurid theropod Masiakasaurus knopfleri Sampson et al., 2001, is now two-thirds complete. We describe Masiakasaurus knopfleri in detail on the basis of examination of new specimens and emphasis on previously unknown elements. The skull is anteroposteriorly long but low in height, unlike the foreshortened abelisaurid condition. P...