| shearing mechanics and the influence of a flexible symphysis during oral food processing in sphenodon (lepidosauria: rhynchocephalia). | the new zealand tuatara, sphenodon, has a specialized feeding system in which the teeth of the lower jaw close between two upper tooth rows before sliding forward to slice food apart like a draw cut saw. this shearing action is unique amongst living amniotes but has been compared with the chewing power stroke of mammals. we investigated details of the jaw movement using multibody dynamics analysis of an anatomically accurate three-dimensional computer model constructed from computed tomography s ... | 2012 | 22644955 |
| more than 1000 ultraconserved elements provide evidence that turtles are the sister group of archosaurs. | we present the first genomic-scale analysis addressing the phylogenetic position of turtles, using over 1000 loci from representatives of all major reptile lineages including tuatara. previously, studies of morphological traits positioned turtles either at the base of the reptile tree or with lizards, snakes and tuatara (lepidosaurs), whereas molecular analyses typically allied turtles with crocodiles and birds (archosaurs). a recent analysis of shared microrna families found that turtles are mo ... | 2012 | 22593086 |
| functional relationship between skull form and feeding mechanics in sphenodon, and implications for diapsid skull development. | the vertebrate skull evolved to protect the brain and sense organs, but with the appearance of jaws and associated forces there was a remarkable structural diversification. this suggests that the evolution of skull form may be linked to these forces, but an important area of debate is whether bone in the skull is minimised with respect to these forces, or whether skulls are mechanically "over-designed" and constrained by phylogeny and development. mechanical analysis of diapsid reptile skulls co ... | 2011 | 22216358 |
| micrornas support a turtle + lizard clade. | despite much interest in amniote systematics, the origin of turtles remains elusive. traditional morphological phylogenetic analyses place turtles outside diapsida-amniotes whose ancestor had two fenestrae in the temporal region of the skull (among the living forms the tuatara, lizards, birds and crocodilians)-and allied with some unfenestrate-skulled (anapsid) taxa. nonetheless, some morphological analyses place turtles within diapsida, allied with lepidosauria (tuatara and lizards). most molec ... | 2012 | 21775315 |
| structure and compositional characteristics of caniniform dental enamel in the tuatara sphenodon punctatus (lepidosauria: rhynchocephalia). | the evolution of dental tissues in relation to tooth function is poorly understood in non-mammalian vertebrates. we studied the dentition of sphenodon punctatus, the sole remaining member of the order rhynchocephalia in this light. | 2011 | 21721336 |
| environmentally cued hatching in reptiles. | evidence is accumulating for the widespread occurrence of environmentally cued hatching (ech) in animals, but its diversity and distribution across taxa are unknown. herein i review three types of ech in reptiles: early hatching, delayed hatching, and synchronous hatching. ech is currently known from 43 species, including turtles, crocodilians, lizards, snakes, tuatara, and possibly worm lizards. early hatching caused by physical disturbance (e.g., vibrations) is the most commonly reported ech a ... | 2011 | 21659393 |
| the structural basis of the filament-matrix texture in the avian/reptilian group of hard β-keratins. | avian hard keratin has a filament-matrix texture in which the filaments contain a helical array of twisted β-sheets and the matrix has unusually high concentrations of cysteine, glycine, and tyrosine. x-ray diffraction studies have established that similar filaments exist in the hard keratins of crocodiles, turtles, tuataras, lizards and snakes. here, the relationship between amino acid sequence and the filament-matrix texture is explored in a wide variety of avian and reptilian hard keratins. u ... | 2011 | 20869443 |
| on the relative roles of selection and genetic drift in shaping mhc variation. | genes of the major histocompatibility complex (mhc) have provided some of the clearest examples of how natural selection generates discordances between adaptive and neutral variation in natural populations. the type and intensity of selection as well as the strength of genetic drift are believed to be important in shaping the resulting pattern of mhc diversity. however, evaluating the relative contribution of multiple microevolutionary forces is challenging, and empirical studies have reported c ... | 2010 | 20854274 |
| genetic diversity and differentiation at mhc genes in island populations of tuatara (sphenodon spp.). | neutral genetic markers are commonly used to understand the effects of fragmentation and population bottlenecks on genetic variation in threatened species. although neutral markers are useful for inferring population history, the analysis of functional genes is required to determine the significance of any observed geographical differences in variation. the genes of the major histocompatibility complex (mhc) are well-known examples of genes of adaptive significance and are particularly relevant ... | 2010 | 20723045 |
| a survey of the husbandry of captive tuatara (sphenodon spp.) in relation to factors implicated in nutritional secondary hyperparathyroidism. | to examine selected aspects of the diet and husbandry of captive tuatara (sphenodon spp.) in new zealand, in order to develop recommendations on provision of ultraviolet b light and diet, to reduce the incidence of nutritional secondary hyperparathyroidism (nshp). | 2009 | 19966899 |
| microstructure of dental hard tissues and bone in the tuatara dentary, sphenodon punctatus (diapsida: lepidosauria: rhynchocephalia). | the tuatara, sphenodon, is a small reptile currently restricted to islands off the coast of new zealand where it feeds mainly on arthropods. a widely held misconception is that 'sphenodon does not have real teeth' and instead possesses 'serrations on the jaw bone'. one hatchling and one adult dentary were examined under sem. two longitudinal ground sections 100-microm thick were prepared through a lower canine tooth and its supporting tissues. there was clear evidence of aprismatic enamel (priml ... | 2009 | 19828975 |
| dentary tooth shape in sphenodon and its fossil relatives (diapsida: lepidosauria: rhynchocephalia). | today rhynchocephalia, the sister tax-on to squamata (snakes, lizards and amphisbaenians), is only represented by the tuatara (sphenodon) of new zealand. however, for much of the mesozoic, the group was speciose and globally distributed. historically, the rhynchocephalia were considered to be homogenous and unspecialized but new fossils and new research are overturning this view. as well as differences in body size, body proportions, habit (aquatic vs. terrestrial), and skull structure, their te ... | 2009 | 19828962 |
| the constrictor dorsalis musculature and basipterygoid articulation in sphenodon. | the constrictor internus dorsalis (cid) trigeminal muscles in vertebrates lie between the braincase and the palatoquadrate bar, and in reptiles they are believed to function in the relative movements between braincase and maxillary segment known as kinesis. in amniote taxa, the presence of a synovial basipterygoid articulation (bpa) correlates with presence of the cid. previous descriptions of the cid in the tuatara sphenodon (rhynchocephalia) are inconsistent regarding presence, size and direct ... | 2010 | 19806656 |
| evolutionary, behavioural and molecular ecology must meet to achieve long-term conservation goals. | founder populations in reintroduction programmes can experience a genetic bottleneck simply because of their small size. the influence of reproductive skew brought on by polygynous or polyandrous mating systems in these populations can exacerbate already difficult conservation genetic problems, such as inbreeding depression and loss of adaptive potential. without an understanding of reproductive skew in a target species, and the effect it can have on genetic diversity retained over generations, ... | 2009 | 19761487 |
| how do reproductive skew and founder group size affect genetic diversity in reintroduced populations? | reduced genetic diversity can result in short-term decreases in fitness and reduced adaptive potential, which may lead to an increased extinction risk. therefore, maintaining genetic variation is important for the short- and long-term success of reintroduced populations. here, we evaluate how founder group size and variance in male reproductive success influence the long-term maintenance of genetic diversity after reintroduction. we used microsatellite data to quantify the loss of heterozygosity ... | 2009 | 19732338 |
| timing of organogenesis support basal position of turtles in the amniote tree of life. | the phylogenetic position of turtles is the most disputed aspect in the reconstruction of the land vertebrate tree of life. this controversy has arisen after many different kinds and revisions of investigations of molecular and morphological data. three main hypotheses of living sister-groups of turtles have resulted from them: all reptiles, crocodiles + birds or squamates + tuatara. although embryology has played a major role in morphological studies of vertebrate phylogeny, data on development ... | 2009 | 19389226 |
| influence of major histocompatibility complex genotype on mating success in a free-ranging reptile population. | major histocompatibility complex (mhc) genes are highly polymorphic components of the vertebrate immune system, which play a key role in pathogen resistance. mhc genes may also function as odour-related cues for mate choice, thus ensuring optimal mhc diversity in offspring. mhc-associated mate choice has been demonstrated in some fish, bird and mammal species but it is not known whether this is a general vertebrate phenomenon. we investigated whether mhc-associated mate choice occurs in a wild p ... | 2009 | 19324833 |
| the evolution of the lepidosaurian lower temporal bar: new perspectives from the late cretaceous of south china. | until recently, it was considered axiomatic that the skull of lizards and snakes arose from that of a diapsid ancestor by loss of the lower temporal bar. the presence of the bar in the living new zealand tuatara, sphenodon, was thus considered primitive, corroborating its status as a 'living fossil'. a combination of new fossils and rigorous phylogeny has demonstrated unequivocally that the absence of the bar is the primitive lepidosaurian condition, prompting questions as to its function. here ... | 2010 | 19324758 |
| a sphenodontine (rhynchocephalia) from the miocene of new zealand and palaeobiogeography of the tuatara (sphenodon). | jaws and dentition closely resembling those of the extant tuatara (sphenodon) are described from the manuherikia group (early miocene; 19-16 million years ago, mya) of central otago, new zealand. this material is significant in bridging a gap of nearly 70 million years in the rhynchocephalian fossil record between the late pleistocene of new zealand and the late cretaceous of argentina. it provides the first pre-pleistocene record of rhynchocephalia in new zealand, a finding consistent with the ... | 2009 | 19203920 |
| fine-scale genetic structure of a long-lived reptile reflects recent habitat modification. | anthropogenic habitat fragmentation--ubiquitous in modern ecosystems--has strong impacts on gene flow and genetic population structure. reptiles may be particularly susceptible to the effects of fragmentation because of their extreme sensitivity to environmental conditions and limited dispersal. we investigate fine-scale spatial genetic structure, individual relatedness, and sex-biased dispersal in a large population of a long-lived reptile (tuatara, sphenodon punctatus) on a recently fragmented ... | 2008 | 19140986 |
| discrimination of flicker frequency rates in the reptile tuatara (sphenodon ). | by investigating the mechanisms that underlie the perception of environmental cues, we may begin to understand how the sensory system governs behavioral responses. this is the first empirical study to examine learning and visual sensitivity in a reptile species, the tuatara (sphenodon punctatus). we established a non-intrusive psychophysical method by employing an instrumental paradigm in order to examine discrimination learning and the ability to distinguish different flicker frequencies in the ... | 2009 | 19089401 |
| the functional significance of the lower temporal bar in sphenodon punctatus. | one of the major conundrums in the evolution of vertebrate cranial design is the early loss and frequent redevelopment of the lower temporal bar in diapsids. whereas it has been proposed that the reduction of the lower temporal bar allows for an increase in jaw adductor mass and bite force, this has never been tested experimentally. as the sole recent representative of the rhynchocephalia, sphenodon punctatus is different from other extant lepidosaurians in having a fully diapsid skull and in us ... | 2008 | 19043062 |
| the evolutionary rate of tuatara revisited. | | 2009 | 18976831 |
| climate warming and environmental sex determination in tuatara: the last of the sphenodontians? | | 2008 | 18595838 |
| skull shape and feeding strategy in sphenodon and other rhynchocephalia (diapsida: lepidosauria). | the rhynchocephalia are a group of small diapsid reptiles that were globally distributed during the early mesozoic. by contrast, the only extant representatives, sphenodon punctatus and s. guntheri (tuatara), are restricted to new zealand off-shore islands. the rhynchocephalia are widely considered to be morphologically uniform but research over the past 30 years has revealed unexpected phenotypic and taxonomic diversity. phylogenetically "basal taxa" generally possess relatively simple conical ... | 2008 | 18512698 |
| rapid molecular evolution in a living fossil. | the tuatara of new zealand is a unique reptile that coexisted with dinosaurs and has changed little morphologically from its cretaceous relatives. tuatara have very slow metabolic and growth rates, long generation times and slow rates of reproduction. this suggests that the species is likely to exhibit a very slow rate of molecular evolution. our analysis of ancient and modern tuatara dna shows that, surprisingly, tuatara have the highest rate of molecular change recorded in vertebrates. our wor ... | 2008 | 18255186 |
| epidermal differentiation in embryos of the tuatara sphenodon punctatus (reptilia, sphenodontidae) in comparison with the epidermis of other reptiles. | studying the epidermis in primitive reptiles can provide clues regarding evolution of the epidermis during land adaptation in vertebrates. with this aim, the development of the skin of the relatively primitive reptile sphenodon punctatus in representative embryonic stages was studied by light and electron microscopy and compared with that of other reptiles previously studied. the dermis organizes into a superficial and deep portion when the epidermis starts to form the first layers. at embryonic ... | 2007 | 17532799 |
| functional morphology and evolution of aspiration breathing in tetrapods. | in the evolution of aspiration breathing, the responsibility for lung ventilation gradually shifted from the hyobranchial to the axial musculoskeletal system, with axial muscles taking over exhalation first, at the base of tetrapoda, and then inhalation as well at the base of amniota. this shift from hyobranchial to axial breathing freed the tongue and head to adapt to more diverse feeding styles, but generated a mechanical conflict between costal ventilation and high-speed locomotion. some "liz ... | 2006 | 16861059 |
| proceedings of the smbe tri-national young investigators' workshop 2005. mhc class i genes in the tuatara (sphenodon spp.): evolution of the mhc in an ancient reptilian order. | the major histocompatibility complex (mhc) is an extremely dynamic region of the genome, characterized by high polymorphism and frequent gene duplications and rearrangements. this has resulted in considerable differences in mhc organization and evolution among vertebrate lineages, particularly between birds and mammals. as nonavian reptiles are ancestral to both mammals and birds, they occupy an important phylogenetic position for understanding these differences. however, little is known about r ... | 2006 | 16434436 |
| formation of the corneous layer in the epidermis of the tuatara (sphenodon punctatus, sphenodontida, lepidosauria, reptilia). | the formation of the stratum corneum in the epidermis of the reptile sphenodon punctatus has been studied by histochemical, immunohistochemical, and ultrastructural methods. sulfhydryl groups are present in the mesos and pre-alpha-layer but disappear in the keratinized beta-layer and in most of the mature alpha-layer. this suggests a complete cross-linking of keratin filaments. tyrosine increases in keratinized layers, especially in the beta-layer. arginine is present in living epidermal layers, ... | 2004 | 16351945 |
| characterization of mhc class ii genes from an ancient reptile lineage, sphenodon (tuatara). | the organization and evolution of major histocompatibility complex (mhc) genes vary considerably among vertebrate lineages. mhc genes have been well characterized in mammals, birds, amphibians and fish, but little is known about their organization in reptiles, despite the fact that reptiles occupy an important phylogenetic position for understanding the evolutionary history of both mammalian and avian mhc genes. here we describe the characterization of the first mhc class ii b cdna sequences fro ... | 2005 | 16261382 |
| squamous cell carcinoma in a tuatara (sphenodon punctatus). | a mature male tuatara was presented with a history of recurrent cloacal prolapse. | 2002 | 16032273 |
| photoreceptor cell types in the retina of the tuatara (sphenodon punctatus) have cone characteristics. | the tuatara sphenodon punctatus, restricted to a few new zealand offshore islands and now strictly protected, belongs to the rhynchocephalia, the smallest order of extant reptiles. earlier light microscopical studies on the retina of this species described photoreceptors with both rod- and cone-like features and the presence of a fovea. a limited amount of retinal material from s. punctatus has now allowed us to prepare the first-ever electron microscopic observations on the eye of this reptile. ... | 2005 | 15896966 |
| t cell function in tuatara (sphenodon punctatus). | tuatara are the sole survivors of an entire order of reptiles that thrived during the age of the dinosaurs. therefore, knowledge of their physiology is critical to understanding the phylogeny of reptiles. previous studies of the immune system of the tuatara did not assess t cell function. we analyzed t cell function among six captive tuatara by assessing concanavalin a (con a), phytohemagglutinin (pha) and mixed lymphocyte reaction (mlr) induced t cell proliferation. peripheral blood mononuclear ... | 2005 | 15857660 |
| the pineal eye of the tuatara. | | 2010 | 15850819 |
| nuclear mitochondrial pseudogenes as molecular outgroups for phylogenetically isolated taxa: a case study in sphenodon. | 'living fossil' taxa, by definition, have no close relatives, and therefore no outgroup to provide a root to phylogenetic trees. we identify and use a molecular outgroup in the sole extant lineage of sphenodontid reptiles, which separated from other reptiles 230 million years ago. we isolated and sequenced a partial nuclear copy of the mitochondrial cytochrome b gene. we confirm the copy is indeed not mitochondrial, is older than all extant mitochondrial copies in sphenodon (tuatara), and is the ... | 2004 | 15266297 |
| chromosomes of tuatara, sphenodon, a chromosome heteromorphism and an archaic reptilian karyotype. | we examined karyotypes of the endemic new zealand reptile genus sphenodon (tuatara) from five populations, finding a karyotype unchanged for at least one million years. animals karyotyped were from five geographically distinct populations, representing three groups, namely s. guntheri, s. punctatus (cook strait group), and s. punctatus (northeastern north island group). all five populations have a diploid chromosome number of 2n = 36, consisting of 14 pairs of macrochromosomes and four pairs of ... | 2004 | 15218263 |
| molecular systematics of primary reptilian lineages and the tuatara mitochondrial genome. | we provide phylogenetic analyses for primary reptilia lineages including, for the first time, sphenodon punctatus (tuatara) using data from whole mitochondrial genomes. our analyses firmly support a sister relationship between sphenodon and squamata, which includes lizards and snakes. using sphenodon as an outgroup for select squamates, we found evidence indicating a sister relationship, among our study taxa, between serpentes (represented by dinodon) and varanidae. our analyses support monophyl ... | 2003 | 13678684 |
| immunocytochemical analysis of beta keratins in the epidermis of chelonians, lepidosaurians, and archosaurians. | beta (beta) keratins are present only in the avian and reptilian epidermises. although much is known about the biochemistry and molecular biology of the beta keratins in birds, little is known for reptiles. in this study we have examined the distribution of beta keratins in the adult epidermis of turtle, lizard, snake, tuatara, and alligator using light and electron immunocytochemistry with a well-characterized antiserum (anti-beta(1) antiserum) made against a known avian scale type beta keratin ... | 2002 | 12115916 |
| molecular clocks in reptiles: life history influences rate of molecular evolution. | life history has been implicated as a determinant of variation in rate of molecular evolution amongst vertebrate species because of a negative correlation between body size and substitution rate for many molecular data sets. both the generality and the cause of the negative body size trend have been debated, and the validity of key studies has been questioned (particularly concerning the failure to account for phylogenetic bias). in this study, a comparative method has been used to test for an a ... | 2002 | 11861889 |
| the evolutionary position of turtles revised. | consensus on the evolutionary position of turtles within the amniote phylogeny has eluded evolutionary biologists for more than a century. this phylogenetic problem has remained unsolved partly because turtles have such a unique morphology that only few characters can be used to link them with any other group of amniotes. among the many alternative hypotheses that have been postulated to explain the origin and phylogenetic relationships of turtles, a general agreement among paleontologists emerg ... | 2001 | 11482432 |
| succinic dehydrogenase histochemistry reveals the location of the putative primary visual and auditory areas within the dorsal ventricular ridge of sphenodon punctatus. | in turtles, crocodilians, lizards and snakes, the dorsal ventricular ridge (dvr) is a nuclear cell mass that contains distinct visual and auditory thalamorecipient cell groups. in the tuatara (sphenodon punctatus), the dvr is not organized into diverse cell groups but instead possesses a trilaminar cytoarchitecture resembling that characteristic of the telencephalic cortex in reptiles. to determine if visual and auditory fields might also be present in the dvr of sphenodon punctatus, we used suc ... | 2000 | 10773623 |
| a molecular phylogeny of reptiles. | the classical phylogeny of living reptiles pairs crocodilians with birds, tuataras with squamates, and places turtles at the base of the tree. new evidence from two nuclear genes, and analyses of mitochondrial dna and 22 additional nuclear genes, join crocodilians with turtles and place squamates at the base of the tree. morphological and paleontological evidence for this molecular phylogeny is unclear. molecular time estimates support a triassic origin for the major groups of living reptiles. | 1999 | 9974396 |
| relationships between corticosterone concentration and season, time of day and confinement in a wild reptile (tuatara, sphenodon punctatus). | seasonal and daily variation in basal plasma concentrations of corticosterone and the effect of short-term confinement on plasma corticosterone concentration were examined in wild adult male and female tuatara (sphenodon punctatus) on stephens island, new zealand. males and females sampled immediately upon capture at night (active period) showed significant variation in basal plasma corticosterone among four seasons of the year, and females also showed variation in concentration between reproduc ... | 1998 | 9570930 |
| purification, partial characterization and peptide sequences of vitellogenin from a reptile, the tuatara (sphenodon punctatus). | vitellogenin (vg), a major precursor to egg yolk proteins, was purified from plasma of an estradiol-treated female tuatara (sphenodon punctatus) by mgcl2-edta precipitation and deae-cellulose chromatography. the amino acid composition of tuatara vg is similar to that of other vertebtate vgs and contains a large proportion of serine (13.7 mol/100 mol of total amino acid). the amino acid sequences of the n-terminus of mature vg (33 residues) and of several trypsin- and cnbr-generated peptides were ... | 1997 | 9226877 |
| identification and partial characterization of alpha 2-macroglobulin from the tuatara (sphenodon punctatus). | alpha 2-macroglobulin (alpha 2-m), a large molecular mass proteinase-binding protein, was identified in plasma from tuatara (sphenodon), a rare reptile endemic to new zealand. in this genus, alpha 2-m constitutes 11-13% of total plasma protein (approximately 2.2-3.9 mg/ml). analysis of blood samples collected at approximately monthly intervals from individual tuatara indicated that the plasma level of alpha 2-m remains fairly constant. the subunits of tuatara alpha 2-m have an apparent molecular ... | 1996 | 8925440 |
| mitochondrial gene order adjacent to the control region in crocodile, turtle, and tuatara. | we used the polymerase chain reaction and sequencing of mitochondrial gene junctions adjacent to the 5' end of the control region (light strand orientation) and the 3' end of nd6 to assess whether a representative crocodilian, turtle, or tuatara shares a unique mitochondrial gene order that is found in birds but not in mammals or amphibians. turtles and crocodiles have the same gene order as mammals, except that crocodile has a trnaphe gene inserted between trnapro and the 5' end of the control ... | 1996 | 8728392 |
| a highly divergent retroviral sequence in the tuatara (sphenodon). | vertebrate retroviruses have been classified into a number of different genera, and although many mammalian and avian examples have been characterized, less information exists about the retroviruses present within other vertebrate classes. we designed oligonucleotide primers against two highly conserved motifs within retroviral protease and reverse transcriptase genes and used them to isolate a retroviral fragment from the reptile tuatara (sphenodon). sequence analysis of this element, termed sp ... | 1995 | 7540785 |
| identification of a 130-kda albumin in tuatara (sphenodon) and detection of a novel albumin polymorphism. | electrophoretic, immunochemical, and protein sequence analyses were performed on plasma albumin of the tuatara (sphenodon), a rare reptile endemic to new zealand. the analyses revealed that, unlike other terrestrial vertebrates, tuatara do not seem to possess a 60- to 75-kda plasma albumin. the common form of plasma albumin in this genus has an apparent molecular mass of 130 kda, making it by far the largest albumin reported for any terrestrial vertebrate. starch gel electrophoresis of samples f ... | 1995 | 7575395 |
| higher-level snake phylogeny inferred from mitochondrial dna sequences of 12s rrna and 16s rrna genes. | portions of two mitochondrial genes (12s and 16s ribosomal rna) were sequenced to determine the phylogenetic relationships among the major clades of snakes. thirty-six species, representing nearly all extant families, were examined and compared with sequences of a tuatara and three families of lizards. snakes were found to constitute a monophyletic group (confidence probability [cp] = 96%), with the scolecophidians (blind snakes) as the most basal lineages (cp = 99%). this finding supports the h ... | 1995 | 7700153 |
| environmental sex determination in reptiles: ecology, evolution, and experimental design. | sex-determining mechanisms in reptiles can be divided into two convenient classifications: genotypic (gsd) and environmental (esd). while a number of types of gsd have been identified in a wide variety of reptilian taxa, the expression of esd in the form of temperature-dependent sex determination (tsd) in three of the five major reptilian lineages has drawn considerable attention to this area of research. increasing interest in sex-determining mechanisms in reptiles has resulted in many data, bu ... | 1991 | 1891591 |
| endocrinology of oviposition in the tuatara (sphenodon punctatus): i. plasma steroids and prostaglandins during natural nesting. | plasma concentrations of estradiol, progesterone, prostaglandin (pg) e2 and pgf were measured during three stages of the natural nesting cycle of the tuatara (sphenodon punctatus), a rare new zealand reptile. specifically, we tested whether nesting activity in this species is correlated with significant modifications in plasma concentrations of these hormones. tuatara dig a nest over a period of several nights, oviposit a complete clutch on a single night, and then guard that nest for several ni ... | 1990 | 2378940 |
| absence of daily cycles in plasma sex steroids in male and female tuatara (sphenodon punctatus), and the effects of acute capture stress on females. | the possible existence of daily cycles in plasma concentrations of sex steroids was examined in wild male and female tuatara (sphenodon punctatus). samples were collected from freshly captured animals at dusk, middle of the night, dawn, and middle of the day in january (summer) and july (winter). males showed daily cycles in mean body temperature (tb) in both seasons but no daily cycle in mean plasma testosterone concentration in either season. vitellogenic female tuatara in january and females ... | 1990 | 2354772 |
| fine structure of regenerating caudal spinal cord in adult tuatara (sphenodon punctatus). | a report on the presence of cerebrospinal fluid contacting neurons (csfcn) inside the regenerating caudal spinal cord of adult specimens of the tuatara sphenodon punctatus is given. the cells in question are easily distinguished from amongst ependymal tanicytes of the regenerating cord. large granules of high electron density are particularly common in these neural cells which generally show clear cytoplasm of low electron density. the ultrastructural findings strongly support the idea of a secr ... | 1990 | 1707076 |
| mammal-like dentition in a mesozoic crocodylian. | crocodylian teeth are generally conical with little differentiation in shape along the tooth row. the mandible is incapable of any fore-aft movement, and feeding typically involves little or no intraoral processing. complex, multi-cusped, mammal-like teeth differentiated along the tooth row have been found in a cretaceous crocodylian from malawi. the morphology of the teeth and mandible indicates that food items were processed by back-to-front (proal) movement of the mandible, unlike living croc ... | 1989 | 17741044 |
| thermal sensitivity of reptilian melatonin rhythms: "cold" tuatara vs. "warm" skink. | daily rhythms in plasma melatonin levels were compared in two ecologically diverse reptilian species under natural environmental conditions in autumn. the nocturnal, cold temperature-adapted tuatara (sphenodon punctatus) had a melatonin rhythm of much lower amplitude than did the diurnal desert-adapted sleepy lizard (tiliqua rugosa). experiments in controlled laboratory environments showed that, although both species are capable of attaining a comparable melatonin peak (approximately 750 pmol/l) ... | 1989 | 2719158 |
| [anatomy of the brain of the new zealand gray sphenodon punctatus (sphenodontidae). a quantitative study of the principle subdivisions of the brain]. | this study has been carried out on two adults of the species sphenodon punctatus (sphenodontidae). the results allowed us to establish the numerical features of the brain organization in this species. comparisons were done with regard to a sample of forty various species of lizards, in which six species of lacertids were taken as a mean reference level (platel, 1975). opposite to those of the lacertids (100), the index of encephalization in tuatara has a low value (70.2), but locates sphenodon i ... | 1989 | 2745969 |
| allosteric transition in hemoglobin (alpha 2a beta 2i) from the rhynchocephalian reptile relict sphenodon punctatus. | the major hemoglobin component hb a of the tuatara, sphenodon punctatus, a relict of the rhynochocephalian reptiles that lived 200 million years ago, was investigated in the light of the apparent contradiction inherent in an effect of organic phosphate cofactors on the oxygen affinity of hemoglobins exhibiting hyperbolic oxygen equilibrium curves. the heterotropic allosteric effect of atp, the major erythrocytic cofactor in the tuatara, is shown to be correlated with distinct homotropic interact ... | 1989 | 2634664 |
| comparative fine structure of the axial skeleton inside the regenerated tail of some lizard species and the tuatara (sphenodon punctatus). | the regenerated tail of the new zealand gecko hoplodactylus maculatus is equipped with an elastic cartilaginous tube as skeletal axis. other lizard species and sphenodon punctatus possess variably developed hyaline cartilaginous tubes. moreover, h. maculatus enhances the functional performance of its tail by long elastic fibres, which are arranged all around the central regenerated spinal cord. the different characteristics of the regenerated skeleton could be related to the different environmen ... | 1989 | 2606315 |
| an investigation of the functioning of the two major haemoglobins of the sphenodon using fast reaction kinetic methods. | the blood of the sphenodon (sphenodon punctatus) has been fractionated into two major and one minor haemoglobin components by ion-exchange chromatography. the two major haemoglobins have been studied in terms of their kinetic reactions with both o2 and co. the combination of flash photolysis and stopped-flow indicates kinetic differences between two states of the proteins identified with the allosteric t and r forms. the major kinetic findings show that (i) in these haemoglobins the t state is r ... | 1988 | 3415645 |
| similarity in yolk-platelet structure of an ancient bony fish (acipenser) and an ancient reptile (sphenodon). | lipovitellin-phosvitin crystals from oocytes of the sturgeon (acipenser boeri l.) and the tuatara (sphenodon punctatus [gray]) have been shown to he orthorhombic like all such known crystals from vertebrates higher than cyclostomes. lattice parameters and projected crystal views also resembled closely the hitherto known cases. the high evolutionary conservation of this crystal structure probably reflects a cell-biological significance of the tertiary structure of crystal constituents, especially ... | 1986 | 18620159 |
| absence of cooperative haemoglobin-oxygen binding in sphenodon, a reptilian relict from the triassic. | it is generally accepted that the sigmoidal nature of the haemoglobin-oxygen dissociation curve (odc) is necessary for efficient oxygen transport in terrestrial vertebrates because it allows large volumes of oxygen to be bound or released for relatively small changes in the partial pressure of oxygen (po2) in the blood. furthermore, the amount of oxygen to tissues is increased by hydrogen ions produced from the dissociation of carbon dioxide in solution. the generality of these key features of c ... | 2013 | 6646231 |
| ultrastructural observations on the granular leucocytes of the tuatara sphenodon punctatus (gray). | the granular leucocytes of an active, mature female tuatara, sphenodon punctatus (gray) were examined in the electron microscope. eosinophils contained a lobulated nucleus, homogeneous, dense, irregularly shaped granules, assorted smaller granular inclusions, mitochondria and beta-glycogen. endoplasmic reticulum, golgi complexes and ribosomes were scanty. immature neutrophils (myelocytes) were regular in outline and contained a compact nucleus. in the adjacent centrosomal region were paired cent ... | 1979 | 574993 |
| ultrastructural observations on the erythrocytes and thrombocytes of the tuatara, sphenodon punctatus (gray). | the erythrocytes of sphenodon punctatus (gray) are nucleated, ellipsoidal and flattened, and contain 55--65 microtubules in their marginal band. the thrombocytes are also flattened, ellipsoidal, nucleated cells and in electron-microscopic preparations occurred in aggregrates. the thrombocytes appeared to be 'activated' and possessed many pseudopodia which were devoid of organelles. the latter were concentrated in the perinuclear region and were encircled by a ring of microtubules. the organelles ... | 1979 | 230613 |
| ear and hearing in sphenodon punctatus. | observations on sphenodon punctatus have revealed new features of the anatomy of the ear,and measurements in a living specimen by means of cochlear potentials show the form and level of this ear's performance in sound reception. for an animal lacking an external ear opening and a functional tympanic membrane, the sensitivity of from 100-900 hz is surprisingly good in low tones with peak response around 200-400 hz. the inner ear is well developed, with a tectorial membrane connected to a tectoria ... | 1976 | 1069313 |
| [lung structure of sphenodon punctatus. a comparative anatomic study]. | after a critical review of the literature, the authors describe the structure of the lung of sphenodon, dealing with form, arteries, veins, and septation. the external form, circulatory pattern, degree of complication, height of the septa, vascular structure, and decrease in complication (?) are discussed from the standpoint of comparative anatomy. in an attempt to explain the unusual findings, the capacity for development of the central and subpleural type of differentiation is compared and con ... | 1976 | 941670 |
| [details of the muscular and nervous system in the anterior member of sphenodon punctatus (reptiles-rhynchocephales)]. | sphenodom is the only lepidosaurian with an organisation of the nervous ways in the anterior member which constitute an important stage in tetrapod evoluation. squamata are exceptions. the radial nerve is developed and possesses the most important part of the fibres for the dorsal muscles of the forearm. the flexor canal is separated into 2 voluminous trunks. | 1975 | 1205113 |
| [contribution to the histology of the external nasal glands of sphenodon punctatus (reptilia, rhynchoecephalia)]. | | 1973 | 4704395 |
| [quantity of deoxyribonucleic acid per nucleus and nuclear areas of erythrocytes in rhynchocephalic reptile, sphenodon punctatus]. | | 1971 | 5164401 |
| microsporidiosis in the tuatara. | | 1971 | 5153878 |
| changes in oxygen consumption and heart-rate with activity and body temperature in the tuatara, sphenodon punctatum. | | 1970 | 5428028 |
| nitrogen excretion in the tuatara, sphenodon punctatus. | | 1969 | 5351975 |
| the bulbus cardis and its septa in sphenodon punctatus. | | 1969 | 5343863 |
| adipose tissue reactivity of sphenodon punctatus and a species of new zealand skink. | | 1969 | 5777400 |
| observations on the epidermis of the tuatara (sphenodon punctatus). | | 1968 | 5693711 |
| [a study on the heart in the tuatara, sphenodon (hatteria) punctatus gray]. | | 1966 | 5925681 |
| [the 3d type of proximal hypothalamo-hypophyseal contact: the median eminence of sphenodon punctatus]. | | 1964 | 14196822 |
| [histological peculiarities of the adrenal gland in sphenodon punctatus gray (rhyncocephalian reptile)]. | | 1964 | 14145392 |
| [on vitali's organ in sphenodon punctatus gray]. | | 1963 | 14010462 |
| [the foveal structure of the retina in sphenodon punctatus]. | | 1951 | 14839859 |
| [the general organization of the neural retina in sphenodon punctatus]. | | 1951 | 14839858 |
| [morphological value of the retinal photoreceptor in the hatteria (sphenodon punctatus)]. | | 1951 | 14839857 |
| the normal and parietal eyes of the tuatara. | | 1947 | 20243480 |
| emydomyces testavorans, a new genus and species of onygenalean fungus isolated from shell lesions of freshwater aquatic turtles. | the fungal order onygenales includes many pathogens of humans and animals, and recent studies have shown some onygenalean fungi to be significant emerging pathogens of reptiles. although many of these fungi have similar morphological features in histologic tissue sections, recent molecular analyses have revealed a genetically complex and diverse group of reptile pathogens comprising several genera, most notably nannizziopsis, ophidiomyces, and paranannizziopsis infections by members of these gen ... | 2019 | 30487306 |
| thermoregulation of a temperate reptile in a forested habitat. | a major focus in zoology is to understand the phenotypic responses of animals to environmental variation. this is particularly important when dealing with ectotherms in a thermally heterogenous environment. we measured body temperatures of a free-ranging, medium sized temperate reptile, the tuatara, sphenodon punctatus, to investigate its thermal opportunities and the degree to which the animal actively regulates its body temperature. we found high variation in body temperature between individua ... | 2018 | 29500060 |
| extreme thermal fluctuations from climate change unexpectedly accelerate demographic collapse of vertebrates with temperature-dependent sex determination. | global climate is warming rapidly, threatening vertebrates with temperature-dependent sex determination (tsd) by disrupting sex ratios and other traits. less understood are the effects of increased thermal fluctuations predicted to accompany climate change. greater fluctuations could accelerate feminization of species that produce females under warmer conditions (further endangering tsd animals), or counter it (reducing extinction risk). here we use novel experiments exposing eggs of painted tur ... | 2019 | 30862793 |
| sphenodon punctatus (tuatara). | | 2020 | 33097277 |
| learning in non-avian reptiles 40 years on: advances and promising new directions. | recently, there has been a surge in cognition research using non-avian reptile systems. as a diverse group of animals, non-avian reptiles [turtles, the tuatara, crocodylians, and squamates (lizards, snakes and amphisbaenids)] are good model systems for answering questions related to cognitive ecology, from the role of the environment on the brain, behaviour and learning, to how social and life-history factors correlate with learning ability. furthermore, given their variable social structure and ... | 2020 | 33073470 |
| the untapped potential of reptile biodiversity for understanding how and why animals age. | 1. the field of comparative aging biology has greatly expanded in the past 20 years. longitudinal studies of populations of reptiles with a range of maximum lifespans have accumulated and been analyzed for evidence of mortality senescence and reproductive decline. while not as well represented in studies of amniote senescence, reptiles have been the subjects of many recent demographic and mechanistic studies of the biology of aging. 2. we review recent literature on reptile demographic senescenc ... | 2020 | 32921868 |
| palaeontological evidence reveals convergent evolution of intervertebral joint types in amniotes. | the intervertebral disc (ivd) has long been considered unique to mammals. palaeohistological sampling of 17 mostly extinct clades across the amniote tree revealed preservation of different intervertebral soft tissue types (cartilage, probable notochord) seen in extant reptiles. the distribution of the fossilised tissues allowed us to infer the soft part anatomy of the joint. surprisingly, we also found evidence for an ivd in fossil reptiles, including non-avian dinosaurs, ichthyosaurs, plesiosau ... | 2020 | 32839497 |
| publisher correction: the tuatara genome reveals ancient features of amniote evolution. | an amendment to this paper has been published and can be accessed via a link at the top of the paper. | 2020 | 32811988 |
| structure and topology of the linkers in the conserved lepidosaur β-keratin chain with four 34-residue repeats support an interfilament role for the central linker. | the β-keratin chain with four 34-residue repeats that is conserved across the lepidosaurs (lizards, snakes and tuatara) contains three linker regions as well as a short, conserved n-terminal domain and a longer, more variable c-terminal domain. earlier modelling had shown that only six classes of structure involving the four 34-residue repeats were possible. in three of these the 34-residue repeats were confined to a single filament (classes 1, 2 and 3) whereas in the remaining three classes the ... | 2020 | 32800921 |
| tuatara genome reveals diverse insights into a remarkable reptile. | | 2020 | 32760036 |
| the tuatara genome reveals ancient features of amniote evolution. | the tuatara (sphenodon punctatus)-the only living member of the reptilian order rhynchocephalia (sphenodontia), once widespread across gondwana1,2-is an iconic species that is endemic to new zealand2,3. a key link to the now-extinct stem reptiles (from which dinosaurs, modern reptiles, birds and mammals evolved), the tuatara provides key insights into the ancestral amniotes2,4. here we analyse the genome of the tuatara, which-at approximately 5 gb-is among the largest of the vertebrate genomes y ... | 2020 | 32760000 |
| heat tolerance of reptile embryos: current knowledge, methodological considerations, and future directions. | aspects of global change result in warming temperatures that threaten biodiversity across the planet. eggs of non-avian, oviparous reptiles (henceforth "reptiles") are particularly vulnerable to warming due to a lack of parental care during incubation and limited ability to behaviorally thermoregulate. because warming temperatures will cause increases in both mean and variance of nest temperatures, it is crucial to consider embryo responses to both chronic and acute heat stress. although many st ... | 2020 | 32757379 |
| identification of epidermal differentiation genes of the tuatara provides insights into the early evolution of lepidosaurian skin. | the tuatara (sphenodon punctatus) is the phylogenetically closest relative of squamates (including lizards and snakes) from which it diverged around 250 million years ago. together, they constitute the clade lepidosauria. fully terrestrial vertebrates (amniotes) form their skin barrier to the environment under the control of a gene cluster, termed the epidermal differentiation complex (edc). here we identified edc genes in the genome of the tuatara and compared them to those of other amniotes. t ... | 2020 | 32732894 |
| bite force data suggests relationship between acrodont tooth implantation and strong bite force. | extant and extinct reptiles exhibit numerous combinations of tooth implantation and attachment. tooth implantation ranges from those possessing roots and lying within a socket (thecodonty), to teeth lying against the lingual wall of the jawbone (pleurodonty), to teeth without roots or sockets that are attached to the apex of the marginal jawbones (acrodonty). attachment may be ligamentous (gomphosis) or via fusion (ankylosis). generally speaking, adaptative reasonings are proposed as an underlyi ... | 2020 | 32656000 |
| general and specific microscopic characteristics of the dorsal tail scales and the spines of the crest in the tuatara sphenodon pucntatus (reptilia; rhynchocephalia; sphenodontidae). | dorsal crest scales and those of the tail spines of the tuatara (sphenodon punctatus) represent different specializations involved in display and protection. erection of the dorsal crest occurs in males during combat and courtship, but tail spines are not noticeably involved in these activities. in both scale derivatives corneous beta proteins (cbps, formerly called beta-keratins) and intermediate filaments keratins (ifks) were determined by immunolabelling. the dermis is dense with few sparse f ... | 2020 | 32569859 |
| evolution: herbivore-type teeth in a cretaceous tuatara relative. | in a new study, leblanc and co-workers have discovered an unusually complex dentition in a fossil relative of the modern-day tuatara that features compound occlusal surfaces, thick and prismatic enamel, and a novel enamel-to-bone tooth attachment. this finding suggests that complex dentitions arose independently in several reptilian lineages. | 2020 | 32369750 |
| unique tooth morphology and prismatic enamel in late cretaceous sphenodontians from argentina. | mammals and reptiles have evolved divergent adaptations for processing abrasive foods. mammals have occluding, diphyodont dentitions with taller teeth (hypsodonty), more complex occlusal surfaces, continuous tooth eruption, and forms of prismatic enamel that prolong the functional life of each tooth [1, 2]. the evolution of prismatic enamel in particular was a key innovation that made individual teeth more resilient to abrasion in early mammals [2-4]. in contrast, reptiles typically have thin, n ... | 2020 | 32220319 |