- Department of Biological Sciences
Sam Houston State University
1900 Ave. I, Lee Drain Building (LDB) Suite 300
Huntsville, Texas 77341-2116
USA - +1 936-294-4250
Juan Diego Daza
Sam Houston State University, Biological Sciences, Faculty Member
- Lepidosaurs, Paleontology, Evolutionary Biology, Cladistics (Systematic Biology), Squamates, Biology, and 14 moreRana catesbeiana, Zoology, Cancer, Biological Sciences, Herpetology, Vertebrate Paleontology, Medical Imaging, Phylogenetics, Vertebrate Evolution, Computed Tomography, Reptiles, Lizards, Bone Biology, and Anatomyedit
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John Paul Richard Thomas is among the living herpetologists to have described the greatest number of new species of amphibians and reptiles, and his contributions to the herpetology of the West Indies, particularly the Greater Antilles,... more
John Paul Richard Thomas is among the living herpetologists to have described the greatest number of new species of amphibians and reptiles, and his contributions to the herpetology of the West Indies, particularly the Greater Antilles, have been exceptional. His academic career followed an unusual path, having established a strong reputation and described 50 new taxa prior to beginning his doctoral studies. His career was strongly influenced by Albert Schwartz and later was characterized by extensive and fruitful collaboration with S. Blair Hedges. Thomas' contributions to the study of blind snakes have been noteworthy. In addition to describing 28 species of scolecophidians he has been a keen observer of blind snake morphology and his 1976 dissertation remains a valuable source of osteological data. We outline some of the highlights of the career of Richard Thomas and provide a bibliography of his scientific works and a listing of the 108 taxa of amphibians and reptiles described by him.
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Research Interests: Zoology, Herpetology, Biology, Skull, Squamata, and 3 moreSynapomorphy, Monophyly, and Ecological Applications
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ABSTRACT Gobekko cretacicus, a Cretaceous lizard from the Gobi Desert of Mongolia, is a key fossil for understanding gecko phylogeny. We revisit this fossil using high-resolution X-ray computed tomography. The application of this imaging... more
ABSTRACT Gobekko cretacicus, a Cretaceous lizard from the Gobi Desert of Mongolia, is a key fossil for understanding gecko phylogeny. We revisit this fossil using high-resolution X-ray computed tomography. The application of this imaging method reveals new information about sutures, bone shape, and structural details of the palate and basicranium. These data were used to assess the phylogenetic affinities of Gobekko in the context of an existing squamate data set. The effects of character ordering, search strategy, and the addition of another putative gekkonomorph (Hoburogekko suchanovi) on inferred gekkonomorph relationships were explored. Available specimens of G. cretacicus are skeletally mature but have unfused nasals, frontals, and parietals, and (possibly) a persistent basicranial fenestra. Some putative gekkonomorphs are not consistently supported as closer to crown clade gekkotans than to autarchoglossans. In a strict consensus both Gobekko and Hoburogekko form a polytomy with extant geckos. Some of the adult character states of Gobekko are observable in embryos of extant species. The evolution of tubular frontals and dentaries in gekkotans may be structurally related to the loss of the postorbital and supratemporal bars in this lineage. The complete lack of a parietal foramen, and presumably a light-sensitive parietal eye, in this clade is of interest and could indicate an early origin of nocturnality in geckos. © 2013 The Linnean Society of London
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We here describe a new gekkotan lizard from the earliest Eocene (MP 7) of the Dormaal locality in Belgium, from the time of the warmest global climates of the past 66 million years (Myr). This new taxon, with an age of 56 Myr, together... more
We here describe a new gekkotan lizard from the earliest Eocene (MP 7) of the Dormaal locality in Belgium, from the time of the warmest global climates of the past 66 million years (Myr). This new taxon, with an age of 56 Myr, together with indeterminate gekkotan material reported from Silveirinha (Portugal, MP 7) represent the oldest Cenozoic gekkotans known from Europe. Today gekkotan lizards are distributed worldwide in mainly warm temperate to tropical areas and the new gecko from Dormaal represents a thermophilic faunal element. Given the Palaeocene–Eocene thermal maximum at that time, the distribution of this group in such northern latitudes (above 50° North – the latitude of southern England) is not surprising. Although this new gekkotan is represented only by a frontal (further, dentaries and a mandibular fragment are described here as Gekkota indet. 1 and 2—at least two gekkotan species occurred in Dormaal), it provides a new record for squamate diversity from the earliest ...
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Abstract Lepidosaurian reptiles (squamates and rhynchocephalians) comprise one of the world's most diverse groups of tetrapods, with most of that diversity found in regions of the world that once formed the supercontinent of Gondwana.... more
Abstract Lepidosaurian reptiles (squamates and rhynchocephalians) comprise one of the world's most diverse groups of tetrapods, with most of that diversity found in regions of the world that once formed the supercontinent of Gondwana. In this special section of the Journal of Herpetology, we present both review and original studies on the evolution of lepidosaurs from Gondwana. In this contribution, we provide a brief introduction to those studies and also present metadata collected from the Web of Science on the progress of the study of lepidosaurian evolution. The latter indicate a substantial increase of research interest in multiple aspects of lepidosaur evolution worldwide, with special increase for lepidosaurs from Gondwanan continents. We conclude by setting some of the main goals we hope to achieve in the study of lepidosaurs from Gondwana in the near future.
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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... more
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 because amphibian fossils are poorly preserved, and previous specimens from this group are both rare and mostly badly damaged. Daza et al. describe a set of fossils preserved in amber showing that this group was unusual both in their habitat use (they may been climbers) and their feeding mode, which appears to have been convergent with the ballistic feeding now seen in chameleons (see the Perspective by Wake). Science , this issue p. 687 ; see also p. 654
Research Interests: Geology, Science, Biology, Medicine, Multidisciplinary, and 3 moreCretaceous, Salamander, and Amphibian
We identify a presumed specimen of Sphaerodactylus in amber from the Zoological Research Museum Alexander Koenig as being embedded in copal, rather than amber. Further, the specimen matches the morphology not of a Hispaniolan gecko, but... more
We identify a presumed specimen of Sphaerodactylus in amber from the Zoological Research Museum Alexander Koenig as being embedded in copal, rather than amber. Further, the specimen matches the morphology not of a Hispaniolan gecko, but of the extant Madagascan species Ebenavia boettgeri, which occurs in a known area of copal deposits.
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We report on the predation of Thecadactylus solimoensis (Squamata, Phyllodactylidae) by an owl, Pulsatrix perspicillata (Aves, Strigiformes). Examination of pellets collected from a P. perspicillata roost contained a partial left maxilla... more
We report on the predation of Thecadactylus solimoensis (Squamata, Phyllodactylidae) by an owl, Pulsatrix perspicillata (Aves, Strigiformes). Examination of pellets collected from a P. perspicillata roost contained a partial left maxilla of a gecko. The maxilla contained the following traits, which confirmed the identification of T. solimoensis : the large size of the maxilla, at least 27 tooth loci, a thickened medial side of the maxillary palatal shelf, a horizontal shelf at the base of the facial process, and blade like posterior process that does not taper abruptly. This is the first report of a gecko in the genus Thecadactylus being preyed upon by an owl.
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John Paul Richard Thomas is among the living herpetologists to have described the greatest number of new species of amphibians and reptiles, and his contributions to the herpetology of the West Indies, particularly the Greater Antilles,... more
John Paul Richard Thomas is among the living herpetologists to have described the greatest number of new species of amphibians and reptiles, and his contributions to the herpetology of the West Indies, particularly the Greater Antilles, have been exceptional. His academic career followed an unusual path, having established a strong reputation and described 50 new taxa prior to beginning his doctoral studies. His career was strongly influenced by Albert Schwartz and later was characterized by extensive and fruitful collaboration with S. Blair Hedges. Thomas' contributions to the study of blind snakes have been noteworthy. In addition to describing 28 species of scolecophidians he has been a keen observer of blind snake morphology and his 1976 dissertation remains a valuable source of osteological data. We outline some of the highlights of the career of Richard Thomas and provide a bibliography of his scientific works and a listing of the 108 taxa of amphibians and reptiles described by him.
Research Interests:
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... more
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 several features inconsistent with its original phylogenetic placement. Here we describe a more complete, specimen that demonstrates Oculudentavis is actually a bizarre lizard of uncertain position. The new interpretation and phylogenetic placement highlights a rare case of convergent evolution rarely seen among reptiles. Our results re-affirm the importance of Myanmar amber in yielding unusual taxa from a forest ecosystem rarely represented in the fossil record.
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Well-resolved phylogenetic hypotheses and ontogenetic data are often necessary for investigating the evolution of structural novelty. The Sphaerodactylidae comprises 12 genera of predominantly miniaturized geckos. The genera Aristelliger... more
Well-resolved phylogenetic hypotheses and ontogenetic data are often necessary for investigating the evolution of structural novelty. The Sphaerodactylidae comprises 12 genera of predominantly miniaturized geckos. The genera Aristelliger and Teratoscincus are exceptions, with taxa reaching snout-to-vent lengths far exceeding those of other sphaerodactylids. These two genera possess enigmatic, supraorbital ossifications-parafrontal bones-which are encountered nowhere else among squamates. At the time of their discovery, these structures were believed to be the result of evolutionary convergence. Although relationships between other sphaerodactylids remain unresolved, recent molecular and morphological data have supported a close relationship between Aristelliger and Teratoscincus. We investigated the ontogeny of parafrontal bones to better understand relationships between sphaerodactylid body size and the presence of parafrontals, and to evaluate whether ontogenetic data support the ...
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Sesamoids are elements that originate as intratendinous structures due to genetic and epigenetic factors. These elements have been reported frequently in vertebrates, although cranial sesamoids have been recorded almost exclusively in... more
Sesamoids are elements that originate as intratendinous structures due to genetic and epigenetic factors. These elements have been reported frequently in vertebrates, although cranial sesamoids have been recorded almost exclusively in non-tetrapod Osteichthyes. The only tetrapod cranial sesamoids reported until now have been the transiliens cartilage (of crocodiles and turtles), and another one located in the quadrate-mandibular joint of birds. Here, we examined seven squamate species using histological sections, dissections of preserved specimens, dry skeletons, cleared and stained specimens, computed tomographies (CT), and report the presence of other cranial sesamoids. One is attached to the cephalic condyle of the quadrate, embedded in the bodenaponeurosis and jaw adductor muscles of Ophiodes intermedius (Anguidae). The other sesamoid is found at the base of the basicranium of several squamates, capping the sphenoccipital tubercle, on the lateral side of the basioccipital-basisp...
Research Interests: Physiology, Zoology, Herpetology, Skeletal muscle biology, Biology, and 13 moreMorphology, Vertebrate Evolution, Medicine, Anatomy, Lizards, Animals, Skull, Ciencias Biológicas, Comparative Anatomy of Vertebrates, Joints, Sesamoid Bones, Enseñanza - Aprendizaje Ciencias Naturales Y Exactas, and X ray Computed Tomography
The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known.... more
The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known. Here, we present the first Mesozoic acrodontan from Africa, which also represents the oldest iguanian lizard from that continent. The new taxon comes from the Kem Kem Beds in Morocco (Cenomanian, Late Cretaceous) and is based on a partial lower jaw. The new taxon presents a number of features that are found only among acrodontan lizards and shares greatest similarities with uromastycines, specifically. In a combined evidence phylogenetic dataset comprehensive of all major acrodontan lineages using multiple tree inference methods (traditional and implied weighting maximum-parsimony, and Bayesian inference), we found support for the placement of the new species within uromastycines, along withGueragama sulamericana(Late Cretaceous of Brazil). The new fos...
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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... more
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. Twelve specimens from the Albian-Cenomanian boundary of Myanmar (99 Ma) preserve fine details of soft tissue and osteology, and high-resolution x-ray computed tomography permits detailed comparisons to extant and extinct lizards. The extraordinary preservation allows several specimens to be confidently assigned to groups including stem Gekkota and stem Chamaleonidae. Other taxa are assignable to crown clades on the basis of similar traits. The detailed preservation of osteological and soft tissue characters in these specimens may facilitate their precise phylogenetic placement, making them useful calibration points for molecular divergence time...
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The mourning gecko (Lepidodactylus lugubris) is a nocturnal, parthenogenetic species that has been introduced in Colombia. Despite more than 70 years of collecting activity in the country, there has yet to be a thorough evaluation of its... more
The mourning gecko (Lepidodactylus lugubris) is a nocturnal, parthenogenetic species that has been introduced in Colombia. Despite more than 70 years of collecting activity in the country, there has yet to be a thorough evaluation of its distribution in Colombia. Here we review all records from eight museum collections, along with literature reports, to generate a locality map documenting this gecko’s distribution in space and time. Additionally, new sightings are reported and its range expansion in the Cauca rift valley is discussed.
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Aprasia repens is a miniaturised, burrowing, limbless gekkotan belonging to the family Pygopodidae. We used high-resolution X-ray computed tomography to investigate the osteology of this species and describe all ossified elements of the... more
Aprasia repens is a miniaturised, burrowing, limbless gekkotan belonging to the family Pygopodidae. We used high-resolution X-ray computed tomography to investigate the osteology of this species and describe all ossified elements of the skull using terminology standardised for gekkotan lizards. Aprasia repens is characterised by a short mandible comprising only three discrete elements and bearing only two teeth on each ramus; the upper jaw is edentulous (in females). The basicranium is completely fused. The bones of the snout are strongly imbricating. The middle ear is much reduced; no stapes is evident and the fenestra ovalis is confluent with the lateral aperture of the recessus scalae tympani. However, inner-ear morphology suggests normal auditory function. The quadrate is columnar, abuts the paroccipital process, and might play a role in the transmission of ground-borne vibrations to the inner ear. The eyes are smaller than in other gekkotans, but larger than in most fossorial s...
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BackgroundThe retinal pigmented epithelium (RPE) is a rounded shaped structure in almost all lizards. In the New World dwarf geckos, this structure shows an unusual morphology. In addition to this ocular character, we describe notable... more
BackgroundThe retinal pigmented epithelium (RPE) is a rounded shaped structure in almost all lizards. In the New World dwarf geckos, this structure shows an unusual morphology. In addition to this ocular character, we describe notable differences in the development of these geckos in comparison with available developmental staging tables for other geckos and squamate reptiles.ResultsWe identified two main patterns of development of the RPE for squamates. These patterns were mapped onto a metatree of concordant hypotheses of squamates based on molecular data. During post-ovopositional stages the representative species of sphaerodactyls exhibit a RPE layer that transforms gradually from an ovoid form into the generalized spherical form. Sphaerodactyls are the only group of squamates in which this pattern is known.ConclusionsThis transition might be circumstantial evidence that the accessory RPE plays a role in providing additional protection for their apomorphic concaviclivate tempora...
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ABSTRACT This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is... more
ABSTRACT This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
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ABSTRACT Dietary data from a large sample of woodcreepers (16 spp., n = 139), revealed that six species of dendrocolaptids occasionally feed upon lizards and frogs. These birds, which are mainly insectivorous, encounter and feed on... more
ABSTRACT Dietary data from a large sample of woodcreepers (16 spp., n = 139), revealed that six species of dendrocolaptids occasionally feed upon lizards and frogs. These birds, which are mainly insectivorous, encounter and feed on lizards while perching on tree trunks, probably in association with army-ant swarm feeding behaviour. Frog intake may be related to declines in the abundance of invertebrate prey. The bones recovered were identified as one small species of gecko, Gonatodes humeralis, and at least one anuran. We estimate that in the entire sample, about eight lizards and two frogs were ingested. The partially digested gecko material allows determination of which bones are more resistant to digestion, although it is possible that these elements were differentially retained in the stomach. These elements correspond to the more frequently preserved bones in the fossil record of geckos, indicating that the same portions of the skeleton persist under the processes of both digestion and fossilization.
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... Other paratypes were deposited as follows: British Museum of Natural History (BMNH), Catherine Duckett personal collection (CNDC ... band bearing 2-3 sensory pores anteriorly just posterior to palp and many tightly packed stout hairs... more
... Other paratypes were deposited as follows: British Museum of Natural History (BMNH), Catherine Duckett personal collection (CNDC ... band bearing 2-3 sensory pores anteriorly just posterior to palp and many tightly packed stout hairs posteriorly. ... 00 Cmmm *~~~ s--' / 0 v 005mm ...
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... Juan D. Daza,1,2 Janina Aurich2,3 and Aaron M. Bauer2 ... whereas regenerated tails are typically a bright yellow or orange, or a much duller grey to greyish-yellow (see photo-graphs in FitzSimons 1943; Visser 1984; Branch 1988, 1993,... more
... Juan D. Daza,1,2 Janina Aurich2,3 and Aaron M. Bauer2 ... whereas regenerated tails are typically a bright yellow or orange, or a much duller grey to greyish-yellow (see photo-graphs in FitzSimons 1943; Visser 1984; Branch 1988, 1993, 1998; Alexander and Marais 2007; Fig. ...
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ABSTRACT Geckos with a leaf-toed morphology (digits with a single pair of enlarged adhesive pads located terminally) occur on six continents and many islands. Although most leaf-toed gecko genera belong to independently derived lineages,... more
ABSTRACT Geckos with a leaf-toed morphology (digits with a single pair of enlarged adhesive pads located terminally) occur on six continents and many islands. Although most leaf-toed gecko genera belong to independently derived lineages, recent studies support the monophyly of a circum-Indian Ocean group including four genera from disparate regions: the southern African genera Afrogecko and Cryptactites, the Malagasy genus Matoatoa, and the Australian genus Christinus. We obtained molecular and/or morphological data for most species in these genera to estimate phylogenetic relationships among constituent species and infer broad historical biogeographic patterns. Our results confirm that Afrogecko is not monophyletic, and that Christinus is embedded among African taxa. Afrogecko is comprised of three lineages, each of which is distinct in external features and osteology. Based on these results, we partition Afrogecko and recognize two new genera. Molecular clock analyses suggest divergences within the circum-Indian Ocean group are too recent for Gondwanan vicariance or hypothesized land bridges (e.g. Kerguelen Plateau) to account for the observed Africa/Madagascar/Australia distributional pattern. Ancestral area analyses support an origin of the clade in mainland Africa or Madagascar, and imply a dispersal event from southern Africa to Australia, similar to those observed in some plant and arthropod taxa, but otherwise unknown among non-volant terrestrial vertebrates. Dispersal was likely via a southern route and may have been facilitated by island hopping using Antarctica or other southern landmasses available in the mid-Cainozoic.
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Morphologists have historically had to rely on destructive procedures to visualize the three-dimensional (3-D) anatomy of animals. More recently, however, non-destructive techniques have come to the forefront. These include X-ray computed... more
Morphologists have historically had to rely on destructive procedures to visualize the three-dimensional (3-D) anatomy of animals. More recently, however, non-destructive techniques have come to the forefront. These include X-ray computed tomography (CT), which has been used most commonly to examine the mineralized, hard-tissue anatomy of living and fossil metazoans. One relatively new and potentially transformative aspect of current CT-based research is the use of chemical agents to render visible, and differentiate between, soft-tissue structures in X-ray images. Specifically, iodine has emerged as one of the most widely used of these contrast agents among animal morphologists due to its ease of handling, cost effectiveness, and differential affinities for major types of soft tissues. The rapid adoption of iodine-based contrast agents has resulted in a proliferation of distinct specimen preparations and scanning parameter choices, as well as an increasing variety of imaging hardwa...
Research Interests: Comparative Anatomy, Biomedical Engineering, Computed Tomography, Morphology, Medicine, and 11 moreDigital Image Processing, Tomography, Anatomy, Animals, Three Dimensional Imaging, microCT, 3-D Reconstruction, Medical Physiology, Comparative Anatomy of Vertebrates, X ray Computed Tomography, and Contrast Media
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Sphaerodactyl geckos comprise five genera distributed across Central and South America and the Caribbean. We estimated phylogenetic relationships among sphaerodactyl genera using both separate and combined analyses of seven nuclear genes.... more
Sphaerodactyl geckos comprise five genera distributed across Central and South America and the Caribbean. We estimated phylogenetic relationships among sphaerodactyl genera using both separate and combined analyses of seven nuclear genes. Relationships among genera were incongruent at different loci and phylogenies were characterized by short, in some cases zero length, internal branches and poor phylogenetic support at most nodes. We recovered a polyphyletic Coleodactylus, with Coleodactylus amazonicus being deeply divergent from the remaining Coleodactylus species sampled. The C. amazonicus lineage possessed unique codon deletions in the genes PTPN12 and RBMX while the remaining Coleodactylus species had unique codon deletions in RAG1. Topology tests could not reject a monophyletic Coleodactylus, but we show that short internal branch lengths decreased the accuracy of topology tests because there were not enough data along short branches to support one phylogenetic hypothesis over...
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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... more
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. Twelve specimens from the Albian-Cenomanian boundary of Myanmar (99 Ma) preserve fine details of soft tissue and osteology, and high-resolution x-ray computed tomography permits detailed comparisons to extant and extinct lizards. The extraordinary preservation allows several specimens to be confidently assigned to groups including stem Gekkota and stem Chamaleonidae. Other taxa are assignable to crown clades on the basis of similar traits. The detailed preservation of osteological and soft tissue characters in these specimens may facilitate their precise phylogenetic placement, making them useful calibration points for molecular divergence time estimates and potential keys for resolving conflicts in higher-order squamate relationships.