Siobhán B Cooke

Johns Hopkins Medicine | JHUSOM · Center for Functional Anatomy and Evolution

The correlation between diet and dental topography is of importance to paleontologists seeking to diagnose ecological adaptations in extinct taxa. Although the subject is well represented in the literature, few studies directly compare methods or evaluate dietary signals conveyed by both upper and lower molars. Here, we address this gap in our know...

Geometric morphometrics (GM) has increasingly become an important tool in assessing and studying shape variation in a wide variety of taxa. While the GM toolkit has unparalleled power to quantify shape, its uses in studies of functional morphology have been questioned. Here we assess the state of the field of GM and provide an overview of the techn...

A new extinct Late Quaternary platyrrhine from Haiti, Insulacebus toussaintiana, is described here from the most complete Caribbean subfossil primate dentition yet recorded, demonstrating the likely coexistence of two primate species on Hispaniola. Like other Caribbean platyrrhines, I. toussaintiana exhibits primitive features resembling early Midd...

Objectives Previous studies report that geometric measures of incisor size and curvature in extant anthropoid primates correspond to dietary differences. However, other methodologies of assessing incisor shape variation, such as dental topographic analysis, have not been considered. Materials and Methods This study measures Relief Index (RFI), lin...

Our knowledge of the fossil avifauna from the Middle Miocene La Venta locality in Colombia is limited almost entirely to aquatic birds. Phorusrhacidae, popularly known as ‘terror birds’, are a group of highly diversified cursorial birds that played the role of apex predators during most of the Cenozoic. Here we present the first record of a phorusr...

Here we describe new fossil material of Antillothrix bernensis, a Pleistocene-Holocene primate taxon from Hispaniola. It is now represented by seven crania, five mandibles, and dozens of postcranial elements from several paleontologically rich cave systems. The five adult crania included here share a similar overall profile as well as specific feat...

Pathologies of the skull and teeth are well documented for many human populations, but there are fewer studies of other primates. We contrast lesion prevalence and patterning among cercopithecoid primates and map variation onto socioecological variables. We compare craniodental lesions in six species: Nasalis larvatus ( n = 54), Colobus polykomos (...

The extinct endemic monkeys of the Caribbean have been difficult to place phylogenetically and, despite some last appearance dates postdating human arrival on these islands, we have only a basic understanding of their paleobiology and no direct evidence explaining the timing and drivers of their demise. Of the four genera, one is associated with ea...

Neoreomys Ameghino, 1887 is among the most representative genera of South American Miocene rodents. The systematics of this taxon have been unclear, but currently, the most accepted hypothesis places it within Cavioidea, with ambiguous relationships inside the clade. Neoreomys is abundant and well-represented at high latitudes, with two species fro...

Phenomenon: Dissection of cadavers is a common practice in anatomical education. To meet demand for cadavers, some medical institutions facilitate dissection of individuals who did not provide consent during their life. This includes the bodies of individuals who passed away with either no living kin or no kin able to claim and bury their body. Re...

Early research hypothesized that Aotus was a member of a specialized guild of hard-fruit and seed-eating “sclerocarpic harvesters” based largely on their dentognathic morphology. However, these food items remain conspicuously absent in reports from the field. Here, we reconsider the morphology of the feeding apparatus of Aotus, in light of the most...

This contribution contains the 3D models described and figured in: New remains of Neotropical bunodont litopterns and the systematics of Megadolodinae (Mammalia: Litopterna). Geodiversitas.

NOW ( New and Old Worlds ) is a global database of fossil mammal occurrences, currently containing around 68,000 locality-species entries. The database spans the last 66 million years, with its primary focus on the last 23 million years. Whereas the database contains records from all continents, the main focus and coverage of the database historica...

Purpose The infraspinatus muscle is a component of the rotator cuff that has relatively few known variants. Understanding variation in this structure is critical for clinicians and may have implications for understanding human development. Methods One 83-year-old male cadaver was dissected as part of the graduate anatomy education curriculum at Jo...

We present eight new radiocarbon dates for endemic and invasive rodents from Trouing Jérémie #5, a paleontologically-rich sink hole on the Tiburon Peninsula, Haiti. This includes new dates for two species that have been previously directly dated ( Isolobodon portoricensis and Brotomys voratus) as well as three endemic rodents which have no previous...

Degree of femoral neck anteversion distinguishes extinct sloth genera from each other, particularly when analyzed in combination with femoral neck angle. These data have been previously analyzed using a comparative sample including only extant sloths, which limits functional interpretations. Here, we analyze both femoral neck anteversion and femora...

Scientists recognize the Caribbean archipelago as a biodiversity hotspot and employ it for their research as a “natural laboratory”. Yet, they do not always appreciate that these ecosystems are in fact palimpsests shaped by multiple human cultures over millennia. Although post-European anthropogenic impacts are well documented, human influx into th...

The temporomandibular joint is the direct interface between the mandible and the cranium and is critical for transmitting joint reaction forces and determining mandibular range of motion. As a consequence, understanding variation in the morphology of this joint and how it relates to other aspects of craniofacial form is important for better underst...

There are many questions regarding the largest freshwater turtle that ever existed, including how its morphology changed during its ontogeny and how a single ecosystem was able to support more than one group of giant turtles. Here, we report the first individual preserving an associated skull and shell for Stupendemys geographica (currently the lar...

Objectives Craniofacial fluctuating asymmetry (FA) refers to the random deviations from symmetry exhibited across the craniofacial complex and can be used as a measure of developmental instability for organisms with bilateral symmetry. This article addresses the lack of data on craniofacial FA in nonhuman primates by analyzing FA magnitude and vari...

Parocnus dominicanus sp. nov. represents a new species of megalonychid ground sloth from the Altagracia Province of southeastern Dominican Republic. Specimens of multiple individuals, including one associated partial skeleton, were recovered from two separate underwater caves in the Parque Nacional del Este through collaborations with museums and c...

The process of mastication is often described as dynamic, involving bending, torsional and shear stresses of the corpus, all of which can drive the shape of the jaw’s internal structure over one’s lifetime. This has been studied in a number of primate species. The black-and-white ruffed lemur (Varecia variegata) is one of the most frugivorous lemur...

We found that when researchers preferentially seek to only landmark specimens in good condition, they may be ignoring entire demographic-specific shape data from groups of individuals more likely to exhibit damage and/or pathology.

Obtaining coordinate data for geometric morphometric studies often involves the sampling of dry skeletal specimens from museum collections. But many specimens exhibit damage and/or pathologic conditions. Such specimens can be considered inadequate for the analyses of shape and are excluded from study. However, the influences that damaged specimens...

Extinct sloths represent a wide range of morphological, locomotor, and body size variation. Researchers have examined femoral neck angle in two dimensions to hypothesize locomotor behaviors in this group; however, this measure does not account for femoral neck anteversion. Here, we present a new method for quantifying femoral neck anteversion angle...

Antillothrix bernensis , an extinct platyrrhine primate from the Dominican Republic, has been under intensive study following a series of new finds from two flooded cave sites. To date, three nearly complete crania and one mandible have been described, but none of them preserve the anterior dentition. This study reports the first discovery of Antil...

The anteriorly‐projecting femoral head/neck of some extinct sloths has been noted; however, neck angle has never been quantified from a 3D perspective, despite its potential usefulness in taxonomic and functional interpretations. Here, we present a method to quantify femoral neck torsion in extinct and extant sloths. Seventy femora from four genera...

Late Quaternary fossils representing a locally extinct population of the Cuban crocodile (Crocodylus rhombifer) are reported from two underwater caves in the Dominican cny DOM A large fossil sample of C. rhombifer, from Oleg's Bat Cave near Bavaro in the southeastern Dominican cny DOM, consists of four nearly complete skulls, numerous isolated cran...

Hispaniola once had a large and diverse endemic rodent community. Today, a single species, Plagiodontia aedium, survives alongside invasive murids. Ecological adaptations and resource competition among species have not been previously studied. Here, we undertake the first investigation of the foraging ecology of the endemic taxa using estimated bod...

Exploration of elements of fossil sloths from Hispaniola that exhibit very distinct osteopathologies. Of the few pathological bones, two show bony remodeling consistent with osteomyelitis, two additional elements exhibit morphological changes consistent with healed chronic fractures, and osteophytosis and bony remodeling consistent with severe musc...

In this study, we assess the precision, accuracy, and repeatability of craniodental landmarks (Types I, II, and III, plus curves of semilandmarks) on a single macaque cranium digitally reconstructed with three different surface scanners and a microCT scanner. Nine researchers with varying degrees of osteological and geometric morphometric knowledge...

Body mass is an important component of any paleobiological reconstruction. Reliable skeletal dimensions for making estimates are desirable but extant primate reference samples with known body masses are rare. We estimated body mass in a sample of extinct platyrrhines and Fayum anthropoids based on four measurements of the articular surfaces of the...

The extensive postglacial mammal losses in the West Indies provide an opportunity to evaluate extinction dynamics, but limited data have hindered our ability to test hypotheses. Here, we analyze the tempo and dynamics of extinction using a novel data set of faunal last-appearance dates and human first-appearance dates, demonstrating widespread over...

The Jamaican primate, Xenothrix mcgregori, regarded variously as either a pitheciid or a stem platyrrhine, was the terminal branch of a clade that likely entered the West Indies at least as early as the Early Miocene, although its lineage is represented by fossils of Quaternary age only. We present a new direct radiocarbon-based date of 1,477 ± 34...

Recent paleontological collection in submerged caves in the eastern Dominican Republic has yielded new specimens of Antillothrix bernensis. Here we describe a complete cranium of an adult individual (MHD 20) and provide phenetic comparisons to other endemic Caribbean taxa and extant mainland platyrrhines using three-dimensional geometric morphometr...

Three-dimensional geometric morphometrics (3DGM) has become a standard method for describing and analyzing shape variation in the primate skeleton. One promising application of 3DGM is the production of phenetic dendrograms in order to examine patterns of shared morphology and potentially shared evolutionary history. However, because 3DGM is often...

Alouatta is a wide-spread, speciose genus of largely folivorous platyrrhine primates found throughout Central and South America. One of the major questions about the evolution of genus Alouatta pertains to the selective pressures surrounding the development of its largely folivorous diet and unique mandibular and hyoid morphology. The earliest foss...

The extant radiation of Neotropical primates, the platyrrhines, occupy a great variety of ecological niches in the tropical forests of Central and South America. This diversity includes large-bodied suspensory ripe fruit specialists such as Ateles, mid-canopy dwelling seed consuming pitheciids, the predominantly folivorous genera Alouatta and Brach...

There are currently two endemic primate species known from Hispaniola. A large collection of cranial and postcranial specimens of Antillothrix bernensis have been recovered from the eastern and northern Dominican Republic. The second species, Insulacebus toussaintiana, was described from craniodental remains from southwestern Haiti; the sample also...

The howler monkey clade includes species of Alouatta and four extinct genera, Stirtonia, Paralouatta, Protopithecus, and probably Solimoea as well. Contrary to expectations, this radiation may have originated as a largely frugivorous group; advanced, Alouatta-like leaf-eating is a novelty well-developed in the Alouatta-Stirtonia sublineage only. Re...

Endemic New World monkeys are an important element of the extinct mammal faunas of the Caribbean's Greater Antilles. Here we report the first geochronometric evidence that the primate Antillothrix bernensis existed in the Dominican Republic during the Pleistocene, based on the uranium-series age of carbonate speleothem that encased a tibia when it...

La Venta is a Colombian Middle Miocene paleontological site that has yielded fossils critical for understanding the evolution of the platyrrhines and the endemic South American vertebrate fauna that existed prior to the Great American Interchange. Despite being highly fossiliferous, no systematic fossil collection has been conducted at La Venta sin...

Cranial and temporomandibular joint (TMJ) form has been shown to reflect masticatory forces and mandibular range of motion, which vary in relation to feeding strategy. Similarly, the dentition, as the portion of the masticatory apparatus most directly involved in triturating food items, strongly reflects dietary profile. Fine control over condylar...

Dental topographic analysis is the quantitative assessment of shape of three-dimensional models of tooth crowns and component features. Molar topographic curvature, relief, and complexity correlate with aspects of feeding behavior in certain living primates, and have been employed to investigate dietary ecology in extant and extinct primate species...

A mandible of the Hispaniolan primate Antillothrix bernensis, virtually complete and providing the only definitive evidence of the species' lower dentition, has been discovered in a submerged Dominican Republic cave. The new specimen enables a more certain assessment of the species' phylogenetic position than previously possible. It belongs to the...

The fossil record of bats is extensive in the Caribbean, but few fossils have previously been reported from the Dominican Republic. In this paper, we describe new collections of fossil bats from two flooded caves in the Dominican Republic, and summarize previous finds from the Island of Hispaniola. The new collections were evaluated in the context...

Among living New World monkeys, Howlers and Muriquis are by far the most folivorous. We examine how well the morphology and behavior of Alouatta and Brachyteles conform to leaf-eating adaptational models derived from other studies. Both genera match these expectations unevenly, which suggests a broader conception of primate folivory is in order. He...

A three-dimensional geometric morphometric approach was employed to examine shape variation in laser-scan generated models of lower second molars and its relationship to diet in a sample of 9 extant and 16 extinct platyrrhine genera. Principal component analysis of twenty-three x,y,z landmarks describing the occlusal table and sidewalls showed that...

The nearly pristine remains of Antillothrix bernensis, a capuchin-sized (Cebus) extinct platyrrhine from the Dominican Republic, have been found submerged in an underwater cave. This represents the first specimen of an extinct Caribbean primate with diagnostic craniodental and skeletal parts in association, only the second example of a skull from t...

Spider monkeys are one of the most widespread New World primate genera, ranging from southern Mexico to Bolivia. Although they are common in zoos, spider monkeys are traditionally very difficult to study in the wild, because they are fast moving, live high in the canopy and are almost always found in small subgroups that vary in size and compositio...