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Introduction
My research interests cover a range of topics concerning the systematics and evolution of African squamates (snakes and lizards) and amphibians. I am particularly interested in the evolutionary patterns of the Cordylidae, a family of diversely armored lizards that are endemic to Sub-Saharan Africa. This work requires a combination of morphological, biogeographical and phylogenetic analyses to untangle the complex processes that drive diversification.
Current institution
Additional affiliations
October 2015 - present
September 2001 - October 2005
October 2013 - October 2015
Education
September 2009 - September 2013
Richard Gilder Graduate School
Field of study
- Comparative Biology
August 2007 - June 2009
September 2001 - June 2005
Publications
Publications (129)
Metamorphosis, a common and spectacular developmental process, involves major phenotypic changes often linked to environmental transitions. Understanding how these changes affect morphological evolution is crucial for examining metamorphosis's evolutionary impacts.
In this study, we analysed the role of metamorphosis and life cycle variation on the...
The first unequivocal fossil of a tupinambine in North America is described on the basis of a single thoracic vertebra from a middle Miocene (Barstovian 2) paleocoastal deposit in southwestern Georgia, USA. Wautaugategu formidus n. gen. n. sp. is a mid- to large-bodied taxon with a unique mosaic of tupinambine features. Vertebral position of the fo...
Lygodactylus geckos represent a well-documented radiation of miniaturized lizards with diverse life-history traits
that are widely distributed in Africa, Madagascar, and South America. The group has diversified into numerous
species with high levels of morphological similarity. The evolutionary processes underlying such diversification
remain enigm...
Scincidae is one of the most species-rich and cosmopolitan clades of squamate reptiles. Abundant disarticulated fossil material has also been attributed to this group, however, no complete pre-Cenozoic crown-scincid specimens have been found. A specimen in Burmite (99 MYA) is the first fossil that can be unambiguously referred to this clade. Our an...
Nucleotide base composition plays an influential role in the molecular mechanisms involved in gene function, phenotype, and amino acid composition. GC content (proportion of guanine and cytosine in DNA sequences) shows a high level of variation within and among species. Many studies measure GC content in a small number of genes, which may not be re...
Our ability to visualize and quantify the internal structures of objects via computed tomography (CT) has fundamentally transformed science. As tomographic tools have become more broadly accessible, researchers across diverse disciplines have embraced the ability to investigate the 3D structure-function relationships of an enormous array of items....
Organisms that have repeatedly evolved similar morphologies owing to the same selective pressures provide excellent cases in which to examine specific morphological changes and their relevance to the ecology and evolution of taxa. Hosts of permanent parasites act as an independent evolutionary experiment, as parasites on these hosts are thought to...
The impact of preserved museum specimens is transforming and increasing by three-dimensional (3D) imaging that creates high-fidelity online digital specimens. Through examples from the openVertebrate (oVert) Thematic Collections Network, we describe how we created a digitization community dedicated to the shared vision of making 3D data of specimen...
ABSTRACT
Computed microtomography is an important tool for understanding the natural history of species using
biological collections. Here we report the first dietary data of Alsodes cantillanensis Charrier, Correa,
Castro & Méndez, 2015. Using this technique, we found remains of Diplopoda and Coleoptera in the
digestive tract of a male from the ty...
Two partial vertebrae of the rare, large-bodied, aquatic salamander Batrachosauroides are reported from the Upper Miocene Love Bone Bed (late Clarendonian, ~10–9 Ma) Alachua County, Florida. They represent the latest occurrence of Batrachosauroides by 2.8–5.8 million years from previous records and are the latest account of the family Batrachosauro...
Two partial vertebrae of the rare, large-bodied, aquatic salamander Batrachosauroides are reported from the Upper Miocene Love Bone Bed (late Clarendonian, ~10–9 Ma) Alachua County, Florida. They represent the latest occurrence of Batrachosauroides by 2.8–5.8 million years from previous records and are the latest account of the family Batrachosauro...
Establishment of extant terrestrial vertebrate faunas in North America was influenced by a set of factors associated with temporal changes in climate and ecology that operated at different geographic scales. While the biogeography of extant taxa can be inferred from phylogenies, these omit lineages that have gone regionally extinct and for which th...
Premise
Imaging technologies that capture three‐dimensional (3D) variation in floral morphology at micro‐ and nano‐resolutions are increasingly accessible. In herkogamous flowers, such as those of Theobroma cacao , structural barriers between anthers and stigmas represent bottlenecks that restrict pollinator size and access to reproductive organs....
Lygodactylus is the most speciose gekkonid group in Africa, with several additional, candidate species already identified from previous studies. However, in mainland Africa, several groups remain only partially resolved, and there are several taxonomic inconsistencies. Lygodactylus gutturalis was described from Guinea-Bissau in the 1870s and since...
Platypodinae ambrosia beetles depend on mutualistic fungi for food, and both partners cooperate in colonizing dead trees. The fungi are transported in specialized structures (mycangia), but the location of mycangia is unknown in many platypodine species. One species with elusive mycangia is Euplatypus parallelus, widespread in the Americas, and rec...
Reed bamboo is a major ecological and economic resource for many animals, including humans. Nonetheless, the influence of this plant's evolutionary role on the morphology of animal species remains unexplored. Here, we investigated the significance of bamboo habitats as ecological opportunities in shaping the skull morphology of bush frogs ( Raorche...
Female reproduction in squamate reptiles (lizards and snakes) is highly diverse and mode of reproduction, clutch size, and reproductive tract morphology all vary widely across this group of ~11,000 species. Recently, CRISPR genome editing techniques that require manipulation of the female reproductive anatomy have been developed in this group, maki...
Cordylus angolensis (Bocage, 1895) was described 128 years ago on the basis of a single specimen collected at Caconda in the west-central highlands of Angola. Additional specimens referred to this species were collected at ‘Mombolo’ (also in the central highlands) during the Vernay Angola Expedition in 1925. As the holotype was apparently destroyed...
Diffusible iodine-based contrast-enhanced Computed Tomography (diceCT) is now a widely used technique for imaging metazoan soft anatomy. Turtles present a particular challenge for anatomists; gross dissection is inherently destructive and irreversible, whereas their near complete shell of bony plates, covered with keratinous scutes, presents a barr...
Synopsis
How do phenotypic associations intrinsic to an organism, such as developmental and mechanical processes, direct morphological evolution? Comparisons of intraspecific and clade-wide patterns of phenotypic covariation could inform how population-level trends ultimately dictate macroevolutionary changes. However, most studies have focused on...
Osteoderms are bony plates found in the skin of vertebrates, mostly commonly in reptiles where they have evolved independently multiple times, suggesting the presence of a gene regulatory network that is readily activated and inactivated. They are absent in birds and mammals except for the armadillo. However, we have discovered that in one subfamil...
Understanding how selective pressures drive morphological change is a central question in evolutionary biology. Feather lice have repeatedly diversified into convergent ecomorphs, based on how they escape from host defenses in different microhabitats. Here, we used nano-computed tomography scan data of 89 specimens of feather lice, belonging to fou...
The genus Surangea Chitaley et Sheikh, based on permineralized specimens from the Deccan Intertrappean
Beds of central India, was originally considered to represent a fern megasporangium. Reexamination
of original material and new specimens has revealed that the structures are capsular fruits with well-defined
seeds, rather than megasporangia. We d...
Braincase descriptions of lepidosaurian clades (Rhynchocephalia and Squamata) are scarce, and paleoneurological studies are even scarcer when compared to other reptiles. Regarding paleoneurology sensu stricto, so far mosasauroids and snakes (the latter by means of a single published study) remain the better known lepidosaur groups. Further comparis...
Osteoderms are bony plates which develop in the dermis of the skin of vertebrates, most commonly found in fishes and reptiles. They have evolved independently at least eight times in reptiles suggesting the presence of a gene regulatory network which is readily activated and inactivated. The absence of osteoderms in birds and mammals, except for th...
Miniaturization has evolved repeatedly in frogs in the moist leaf litter environments of rainforests worldwide. Miniaturized frogs are among the world's smallest vertebrates and exhibit an array of enigmatic features. One area where miniaturization has predictable consequences is the vestibular system, which acts as a gyroscope, providing sensory i...
Miniaturization has evolved repeatedly in frogs in the moist leaf litter environments of rainforests worldwide. Miniaturized frogs are among the world's smallest vertebrates and exhibit an array of enigmatic features. One area where miniaturization has predictable consequences is the vestibular system, which acts as a gyroscope, providing sensory i...
We here report on a well-preserved juvenile lizard specimen in Albian amber (ca. 110 mya) from the Hkamti site (Myanmar). This new taxon is represented by an articulated skull and the anterior portion of the trunk, including the pectoral girdle and forelimbs. The scleral ossicles and eyelid are also visible, and the specimen exhibits pristine detai...
Dollo's law of irreversibility states that once a complex structure is lost, it cannot be regained in the same form. Several putative exceptions to Dollo's law have been identified using phylogenetic comparative methods, but the anatomy and development of these traits are often poorly understood. Gastrotheca guentheri is renowned as the only frog w...
Several species of Cophomantini are known to have an enlarged prepollex, commonly modified as an osseous
spine. We surveyed the osteology and myology of the prepollex and associated elements of 94 of the 190 species of
Cophomantini, sampling all genera, except Nesorohyla. Two distinct prepollex morphologies were found: a bladeshaped and a spine-sha...
We here report on a well-preserved juvenile lizard specimen in Albian amber (ca. 110 mya) from the Hkamti site in Myanmar. This new taxon, Retinosaurus hkamtiensis gen. et sp. nov., is represented by an articulated skull and the anterior portion of the trunk, including the pectoral girdle and forelimbs. The ocular skeleton (scleral ossicles) and ey...
Scolecophidian snakes have long posed challenges for scholars interested in elucidating their anatomy. The importance, and relative paucity, of high‐quality anatomical data pertaining to scolecophidians was brought into sharp focus in the late 20th century as part of a controversy over the phylogeny and ecological origin of snakes. The basal positi...
The cranial anatomy of blindsnakes has been markedly understudied, with the small size and relative rarity of encountering these subterranean reptiles being significant limiting factors. In this article, we re‐visit the skull anatomy of the Australian southern blind snake Anilios australis Gray, 1845 using microCT data, and produce the first comple...
CT scanning is a technique that is now used widely not only for diagnosing human disease, but also for natural history research. The micro-CT scanner located at the Nanoscale Research Facility at the University of Florida was used to explore the possibilities that the micro-CT scanning can offer for studying immature
stages of Lepidoptera. Compared...
Teeth are present in most clades of vertebrates but have been lost completely several times in actinopterygian fishes and amniotes. Using phenotypic data collected from over 500 genera via micro-computed tomography, we provide the first rigorous assessment of the evolutionary history of dentition across all major lineages of amphibians. We demonstr...
Oculudentavis khaungraae was described based on a tiny skull trapped in amber. The slender tapering rostrum with retracted narial openings, large eyes, and short vaulted braincase led to its identification as the smallest avian dinosaur on record, comparable to the smallest living hummingbirds. Despite its bird-like appearance, Oculudentavis showed...
Habitat is one of the most important factors shaping organismal morphology, but it may vary across life history stages. Ontogenetic shifts in ecology may introduce antagonistic selection that constrains adult phenotype, particularly with ecologically distinct developmental phases such as the free-living, feeding larval stage of many frogs (Lissamph...
Nonnative species are drivers of global change, affecting biodiversity and burdening society with economic costs. Effective management of an invasion relies on the ability to make accurate predictions about the target species' spread and impact. This requires knowledge of the target species' biology, making taxonomic validation critical. Even so, e...
Anolis lizards originated in continental America but have colonized the Greater Antillean islands and recolonized the mainland, resulting in three major groups (Primary and Secondary Mainland and Greater Antillean). The adaptive radiation in the Greater Antilles has famously resulted in the repeated evolution of ecomorphs. Yet, it remains poorly un...
The first amber-embedded fossil representing the lizard family Agamidae, Protodraco monocoli gen. et sp. nov., is described in burmite of the lowermost Cenomanian (ca. 99 Ma; mid-Cretaceous) from northern Myanmar. It is among both the oldest known amber lizards and the oldest fossils of the family. The fossil is a well preserved left hind foot with...
Teeth have been broadly maintained across most clades of vertebrates but have been lost completely at least once in actinopterygian fishes and several times in amniotes. Using phenotypic data collected from over 500 genera via micro-computed tomography, we provide the first rigorous assessment of the evolutionary history of dentition across all maj...
Ancient amphibians preserved in amber
Extant amphibians are represented by three fairly simple morphologies: the mostly hopping frogs and toads, the low-crawling salamanders, and the limbless caecilians. Until the early Pleistocene—and for more than 165 million years—there was another group, the albanerpetontids. We know little about this group bec...
Editor's Note: this Article has been retracted; the Retraction Note is available at https://doi.org/10.1038/s41598-020-75408-8
Recent molecular phylogenetic work has found that Breviceps Merrem, 1820 comprises two major clades, one of which, the B. mossambicus group, is widely distributed across southern sub-Saharan Africa. This group is notable for harboring abundant cryptic diversity. Of the four most recently described Breviceps species, three are members of this group,...
Although Conraua goliath is well known as the largest living frog species, the diversity and evolution of the genus Conraua across sub-Saharan Africa remain poorly understood. We present multilocus phylogenetic analyses of the six currently recognized species that provide insights into divergence times, biogeography, body size evolution and undescr...
Prosymna is a specialized African snake genus lacking close relatives. The evolutionary relationships and history within Prosymna are poorly understood. Here we assembled a multi-gene data set including representatives for 11 of 16 species to investigate the phylogenetic relationships of this group. Our analyses support the monophyly of Prosymna an...
Oculudentavis khaungraae was described based on a tiny skull trapped in amber. The slender tapering rostrum with retracted osseous nares, large eyes, and short vaulted braincase led to its identification as the smallest avian dinosaur on record, comparable to the smallest living hummingbirds. Despite its bird-like appearance, Oculudentavis showed s...
Metamorphosis is widespread across the animal kingdom and induces fundamental changes in the morphology, habitat and resources used by an organism during its lifetime. Metamorphic species are likely to experience more dynamic selective pressures through ontogeny compared with species with single-phase life cycles, which may drive divergent evolutio...
Evolutionary integration (covariation) of traits has long fascinated biologists because of its potential to elucidate factors that have shaped morphological evolution. Studies of tetrapod crania have identified patterns of evolutionary integration that reflect functional or developmental interactions among traits, but no studies to date have sample...
Frogs (Anura) are one of the most diverse vertebrate orders, comprising more than 7,000 species with a worldwide distribution and extensive ecological diversity. In contrast to other tetrapods, frogs have a highly derived body plan and simplified skull. In many lineages of anurans, increased mineralization has led to hyperossified skulls, but the f...
A recent multilocus molecular phylogeny of the large dragon lizards of the genus Smaug Stanley et al. (2011) recovered a south-eastern clade of two relatively lightly-armoured, geographically-proximate species ( Smaug warreni (Boulenger, 1908) and S. barbertonensis (Van Dam, 1921)). Unexpectedly, S. barbertonensis was found to be paraphyletic, with...
The deep ocean is frequently assumed to be a homogeneous system lacking the same diverse life history strategies found in shallower waters. However, as our methods for exploring the deep ocean improve, common assumptions about dispersal, reproduction and behavior are constantly being challenged. Fishes exhibit the most diverse reproductive strategi...
The Florida peninsula in the southeastern United States hosts a rich fauna of frogs and toads (Order Anura) with nearly 30 native species representing five families. In addition to the present-day species, fossils of anurans are known from terrestrial deposits in Florida from the Oligocene, Miocene, Pliocene, and Pleistocene (Table 1). These fossil...
Although our inventory of Earth’s biodiversity remains incomplete, we still require analyses using the Tree of Life to understand evolutionary and ecological patterns. Because incomplete sampling may bias our inferences, we must evaluate how future additions of newly discovered species might impact analyses performed today. We describe an approach...
We report on the first detailed study of the atlas-axis complex in the lizard clade Dibamidae, a family of poorly known fossorial squamates distributed in tropical or subtropical climates. This skeletal bridge is characterized by several features, such as the complete absence of the first intercentrum or the appearance of the first free cervical ri...
Squamates exhibit a vast diversity of body plans, which directly determines habitat use and preference. Here the skeleton of the sand‐swimmer burrower gymnophthalmid, Calyptommatus leiolepis, is analyzed to investigate how its peculiar fossorial locomotion affects its osteology. Calyptommatus leiolepis is a limb‐reduced, short‐intermediate tailed l...
A new species of rupicolous girdled lizard is described from Serra da Neve Inselberg, Namibe Province, southwestern Angola. We sequenced two mitochondrial gene regions (16S and ND2) for the new species and compared these data with those previously published for other Cordylus species. The new species is genetically divergent from the closely relate...
A comprehensive, accurate, and revisable alpha taxonomy is crucial for biodiversity studies, but is challenging when data from reference specimens are difficult to collect or observe. However, recent technological advances can overcome some of these challenges. To illustrate this, we used modern approaches to tackle a centuries-old taxonomic enigma...
Background
One goal of evolutionary developmental biology is to understand the role of development in the origin of phenotypic novelty and convergent evolution. Geckos are an ideal system to study this topic, as they are species‐rich and exhibit a suite of diverse morphologies—many of which have independently evolved multiple times within geckos....
African clawed frogs in the genus Xenopus are found today throughout sub-Saharan Africa and, because of their widespread use as model organisms in biological research, as introduced populations around the world (Measey et al., 2012; Evans et al., 2015). Because all members of the family Pipidae, including Xenopus, are predominantly aquatic frogs wi...
The limbless skink Ophiomorus punctatissimus is a cryptozoic species found in the Peloponnese region of Greece and on the Greek island Kythira. To provide the first thorough description of the cranial and postcranial osteology of this species, both disarticulated specimens and X‐ray computed tomographies of wet‐preserved specimens were examined in...
Atractaspidines are poorly studied, fossorial snakes that are found throughout Africa and western Asia, including the Middle East. We employed concatenated gene-tree analyses and divergence dating approaches to investigate evolutionary relationships and biogeographic patterns of atractaspidines with a multi-locus data set consisting of three mitoch...
Settings for high-resolution CT scans and DOI numbers for supporting files on the Morphosource website, in Microsoft Excel format.
(XLSX)
Insects that depend on microbial mutualists evolved a variety of organs to transport the microsymbionts while dispersing. The ontogeny and variability of such organs is rarely studied, and the microsymbiont's effects on the animal tissue development remain unknown in most cases. Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae or Platypodina...
The Western Ghats (WG) is an escarpment on the west coast of Peninsular India, housing one of the richest assemblages of frogs in the world, with three endemic families. Here, we report the discovery of a new ancient lineage from a high-elevation massif in the Wayanad Plateau of the southern WG. Phylogenetic analysis
reveals that the lineage belong...
We report the discovery of a new genus and species of amber-preserved lizard from the mid-Cretaceous of Myanmar. The fossil is one of the smallest and most complete Cretaceous lizards ever found, preserving both the articulated skeleton and remains of the muscular system and other soft tissues. Despite its completeness, its state of preservation ob...
Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae and Platypodinae) rely on a symbiosis with fungi for their nutrition. Symbiotic fungi are preserved and transported in specialized storage structures called mycangia. Although pivotal in the symbiosis, mycangia have been notoriously difficult to study, given their minute size and membranous st...
African pygmy toads of the genus Poyntonophrynus are some of the least known species of African toads. The genus comprises ten recognized species endemic to sub-Saharan Africa, five of which are restricted to southwestern Africa. Recent field research in Angola provided new material for three species of Poyntonophrynus , including a morphologically...
In 2017 NSF funded “oVert (openVertebrate): Open Exploration of Vertebrate Diversity in 3D,” which is the first Thematic Collections Network devoted entirely to vertebrate morphological specimens. The primary goal of oVert is to generate and serve high-resolution digital three-dimensional data for internal anatomy across vertebrate diversity. oVert...
Frogs are a familiar and diverse component of tropical forests around the world. Yet there is little direct evidence from the fossil record for the antiquity of this association. We describe four fossil frog specimens from mid-Cretaceous (~99 mya) amber deposits from Kachin State, Myanmar for which the associated fauna provides rich paleoenvironmen...
We reviewed the taxonomic status of populations of frogs in the genus Hemiphractus in Panama, which have all been referred to Hemiphractus fasciatus Peters, 1862 for over 40 years. Although relatively few specimens have been collected, mostly juveniles, it is clear that these frogs inhabit three separate upland regions of the country: The Cordiller...
Aims:
Chemokine CXCL12 (stromal derived factor 1: SDF1) has been shown to play important roles in various processes of cardiovascular development. In recent avian studies, CXCL12 signaling has been implicated in guidance of cardiac neural crest cells for their participation in the development of outflow tract and cardiac septum. The goal of this s...
We describe two new species of miniaturized toadlet in the B. pernix group of Brachycephalus (Anura: Brachycephalidae) from the Atlantic Forest of the state of Paraná, southern Brazil. The first new species is distinguished from all congeners by the pale red coloration from the head to the pelvic region, with sides of the body and thighs dorsally y...
Ambrosia beetles and fungi represent an interesting and economically important symbiosis, but the vast majority of ambrosia fungi remain unexplored, hindering research, management of pathogens, and mitigation of invasive species. Beetles in the subtribe Premnobiini are one example of an entire beetle lineage whose fungal symbionts have never been s...
A new species of Brachycephalus (Anura: Brachycephalidae) is described from the Atlantic Forest of northeastern state of Santa Catarina, southern Brazil. Nine specimens (eight adults and a juvenile) were collected from the leaf litter of montane forests 790–835 m above sea level (a.s.l.). The new species is a member of the pernix group by its bufon...
The species diversity of the frog genus Cardioglossa (family Arthroleptidae) is concentrated in the Lower Guinean Forest Zone of Central Africa with most of the 19 species occurring in Cameroon and neighboring countries (Amiet 1972a,b; Blackburn 2008; Hirschfeld et al . 2015). These small leaf-litter frogs are typically found in primary or secondar...
Modern tropical forests harbor an enormous diversity of squamates, but fossilization in such environments is uncommon and little is known about tropical lizard assemblages of the Mesozoic. We report the oldest lizard assemblage preserved in amber, providing insight into the poorly preserved but potentially diverse mid-Cretaceous paleotropics. Twelv...
The girdled lizard genus Cordylus is represented in Angola by two species, Cordylus angolensis and C. machadoi, separated from their nearest congeners by over 700 km. Here we describe a new species, Cordylus namakuiyus sp. nov., endemic to the arid lowlands west of the southern Angolan escarpment. Phylogenetic analysis using three mitochondrial and...
Despite their unassuming appearance and small size, pipid frogs, including the well-known African Clawed Frog Xenopus, are a diverse and evolutionarily informative group of early-diverging Anura. Though their external morphology is not ostensibly varied, pipid braincases are morphologically diverse. Their small size means that they are often recove...