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Crab inquiline in a baculite.
Get PDF16 pages : illustrations (some color), map ; 26 cm.We describe a small crab inside the phragmocone of a heteromorph cephalopod Baculites sp. smooth from the Gammon Ferruginous Member (lower Campanian) of the Pierre Shale in Butte County, South Dakota. The crab Ferricorda kimberlyae (Bishop, 1987) is well preserved with its carapace and pereiopods parallel to and between two septa of the phragmocone. Because of its superb preservation, the specimen is unlikely to have been washed into the phragmocone. The crab probably retreated into the phragmocone chamber to avoid predation or to molt and was subsequently buried by an influx of rapid sedimentation. This is the first instance of inquilinism by a crab in a heteromorph ammonite. Despite the rarity of such fossils, the occurrence of crabs inside ammonite shells was probably not uncommon on sea floors during the Mesozoic. Morphological details of the specimen reveal that Ferricorda is a dynomenid crab
Molecules, morphology and monophyly : resolving pleuronectiform phylogeny and investigating why it has been so difficult to do.
No full textxii, 157 leaves : illustrations (some color)Although adult flatfishes (order Pleuronectiformes) start out in life as bilaterally
symmetrical larvae, they undergo a remarkable metamorphosis, where one eye of the
symmetrical larva migrates to the opposite side of the cranium, resulting in highly
asymmetrical juvenile and adult forms. Because all flatfishes exhibit this bizarre
morphology and variation, both the degree of asymmetry and handedness (direction of
eye migration) exists within the order, this group provides multiple tests of hypotheses
regarding the evolution of bilateral asymmetry and underlying mechanisms.
Unfortunately, undertaking such studies has been elusive because of three major issues
confounding pleuronectiform phylogenetics: 1) relationships of the major groups within
the order remain mostly unresolved, 2) the sister group of flatfishes is unknown, and 3)
monophyly of the assemblage is weakly supported.
To resolve these issues in pleuronectiform phylogenetics, my dissertation research
has focused on: 1) evaluating the effects non-neutral markers on phylogeny estimation,
principally rhodopsin1 (rho), 2) rigorously testing both flatfish monophyly and sistergroup
hypotheses and 3) resolving relationships within the order, re-examining characters
of adult morphology and comparing them to often overlooked larval characters in light of
new phylogenetic hypotheses.
In the first study, Chapter II, I use previously published sequence data from 78
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acanthomorph (including flatfishes) taxa for rho, rnf213, irbp and mll, perform tests for
neutrality, and compare neutral versus non-neutral markers for congruence using tree
distance metrics and topology testing. I find that while the signal provided by rho may
be discordant with the others, neutrality alone does not predict congruence and therefore
should not be used as a justification to omit data.
In the second study, Chapter III, I optimize new molecular markers and sequence
them along with rho and rnf213 for 58 flatfishes and 90 putative outgroups to test
monophyly, intraordinal relationships and sister-group hypotheses. Those sequences
along with data from a previous study are analyzed to determine possible causes for gene
tree incongruence or phylogenetic error. I discover that the new markers are variable,
providing large amounts of data, while being conserved so that alignment is
unambiguous. When combined with the others and analyzed simultaneously, these
markers provide overwhelming support for a monophyletic Pleuronectiformes.
Additionally, I demonstrate that abundant missing data is likely the cause of low
resolution, validate the importance of investigating substitution saturation as a cause of
error and discuss asymmetrical taxonomic distribution as a cause of low resolution at the
base of Carangimorpha.
Finally, in the third study (Chapter IV) I infer an ultrametric tree, recode a
previously published matrix of characters of adult morphology, combine those with new
larval characters and test whether life history is correlated with phylogenic signal.
Further, I investigate the accuracy of ML ancestral character state estimation (ACE) to
determine if these morphological characters provide additional support for hypotheses of
relationships among major pleuronectiform groups. My results suggest that larval
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characters should not be treated as a source of independent data, but do provide
resolution and additional support for novel relationships within Pleuronectiformes,
although they may be in violation of the condition of low rates on ML ACE. Lastly, I
show that because larval characters are mostly pleisiomorphic for the order, and that
larval morphology is similar to that of putative sister groups, these characters are a
potential source of evidence needed to resolve the placement of this lineage within
Acanthomorpha.Richard Gilder Graduate School at the American Museum of Natural History
Relationships of New World porcupines.
No full text36 p. : ill. (some col.), map ; 26 cm.Phylogenetic analyses of cytochrome-b sequence data from 13 of the 15 currently recognized species of New World porcupines were used to test competing taxonomic hypotheses and to explore scenarios of morphological evolution and biogeography. Consistent with previous studies, the monophyly of Erethizontidae (Chaetomys + Erethizon + Coendou) and the monophyly of Erethizontinae (Erethizon + Coendou) were both strongly supported. However, cytochrome-b sequence data provide no support for the reciprocal monophyly of Coendou, "Echinoprocta," and "Sphiggurus" as those taxa were previously recognized by authors. All of the erethizontid species recognized in recent revisionary work and represented by multiple sequences in this study were recovered as monophyletic groups. Maximum-likelihood (ML) analyses of these data recovered the following phylogeny for 11 species of Coendou: ((melanurus (ichillus (pruinosus + vestitus))) ((spinosus (bicolor + nycthemera)) (prehensilis (mexicanus (quichua + rufescens))))). Ancestral-state reconstructions based on the ML topology suggest that several morphological characters emphasized in past erethizontid classifications (size, nasofrontal sinus inflation, and long fur) have evolved homoplasiously. Maximum-likelihood inference of geographic range evolution suggests that the last common ancestor of living erethizontids was a cis-Andean species, and that most subsequent cladogenesis was also cis-Andean; however, at least two trans-Andean dispersal events are plausibly indicated, as well as two separate invasions of Andean landscapes. Among the most remarkable results of this study are almost-identical sequences of Coendou prehensilis from localities spanning 27° of latitude and 25° of longitude; we speculate that a trophic-niche shift might have allowed rapid range expansion of this species, which accounts for almost all known cases of geographic range overlap and sympatry in the genus Coendou
Systematics and morphological diversification of the Cordylidae (Squamata)
No full textxiii, 327 pages : illustrations (chiefly color)The Cordylidae is a species poor but ecologically and morphologically diverse family of lizards endemic to sub-Saharan Africa. Although the majority of the cordylid species are strictly rupicolous (rock dwelling), the family also contains a diverse array of other specialist ecotypes. Due to this concentrated ecological and morphological variation, the family is an excellent system for studying macroevolutionary processes. Previous studies have hypothesized that the majority of diversity in the family evolved rapidly at the base of the viviparous subfamily (Cordylinae), possibly representing an adaptive radiation, but this has not been investigated empirically. The four central chapters of this thesis were designed to be synergistic, with each chapter providing information and helping develop hypotheses in the others. Chapter two places the phylogenetic relationships of the Cordylidae into a temporal framework using relaxed clock Bayesian analyses on an 11 gene, squamate-wide dataset with ten fossil calibrations. These analyses recover the viviparous cordylines as undergoing a period of rapid cladogenesis across the Oligocene-Miocene boundary, radiating into nine well-supported lineages, distributed around the edge of the great escarpment in South Africa. Chapters three and four focused on two different cordylid groups with complicated and unresolved taxomomic histories. By investigating species boundaries within the Smaug warreni species complex (chapter three) and Hemicordylus capensis (chapter four) I address whether the current taxonomy of the family accurately captures the actual species diversity of the family. A combination of phylogenetic, biogeographic and morphological analyses reveals new species within both groups. The fifth chapter attempts to test the hypothesis that the Cordylidae underwent an adaptive radiation following the evolution of viviparity. Morphological variation of the Cordylidae was represented through a combination of standardized ecomorphological measurements and novel, volumetric measurements of osteoderm distributions recovered using High-Resolution CT scanning. Ecological data for known cordylid localities was extracted from multiple commonly used climate layers. Morphological variation was correlated with microhabitat choice, but not with climatic variation. Existing analytical techniques and new methods reveal that the viviparous cordylids experienced an early burst of morphological diversification, while the oviparous subfamily, Platysaurinae, did not. These findings strongly support the hypothesis that the Cordylinae underwent a period of adaptive radiation during the Oligocene, possibly as a result of shifts in the climate and geological uplift of South Africa's Great Escarpment.Richard Gilder Graduate School at the American Museum of Natural History
Pseudodysderina and Tinadysderina.
No full text43 pages : illustrations (some color) ; 26 cm. Part of the oonopid PBI project. (Acknowledgments)A new genus, Pseudodysderina, is established for a group of species that resemble those of Dysderina Simon in having grooves connecting both the anterior and posterior spiracles. These spiders have transverse ridges on the sternum but lack the sternal excavations that characterize Dysderina and are instead united by the highly modified mouthparts of males: the labium is greatly enlarged, with a dorsoventrally flat, posterior portion that extends far posterior of the anterolateral corners of the sternum, and the endites are each deeply excavated, medially around the sides of the labium and laterally around the base of the palpal trochanter. Dysderina desultrix (Keyserling), from Peru, is transferred to Pseudodysderina and chosen as the type species; its male is described for the first time. This species has been taken by canopy fogging and beating foliage as well as in leaf litter, and appears to be widespread in the Amazonian portions of Colombia, Ecuador, Peru, and Brazil. Seven more narrowly distributed new species are described from Peru (P. manu), Bolivia (P. yungas, P. beni), Ecuador (P. hermani), Colombia (P. suiza, P. dracula), and Brazil (P. utinga). The six new species assigned to the new genus Tinadysderina resemble those of Dysderina and Pseudodysderina, but have a much smaller, simpler, weakly sclerotized embolus; they are known only from the western slopes of the Andes in Ecuador (T. tinalandia, T. otonga) and Colombia (T. planada, T. gorgona, T. bremen, T. pereira)
Cranial pneumaticity of the tyrannosaurid Alioramus.
No full text46 pages : illustrations (some color) ; 26 cmArchosaurs and mammals exhibit skeletal pneumaticity, where bone is infilled by air-filled soft tissues. Some theropod dinosaurs possess extensively pneumatic skulls in which many of the individual bones are hollowed out by diverticula of three main cranial sinus systems: the paranasal, suborbital, and tympanic sinuses. Computed tomography (CT scanning) permits detailed study of the internal morphology of cranial sinuses. But only a few theropod specimens have yet been subjected to this type of analysis. We present CT scans of the remarkably preserved and disarticulated skull bones of the long-snouted tyrannosaurid theropod Alioramus. These scans indicate that Alioramus has extensive cranial pneumaticity, with pneumatic sinuses invading the maxilla, lacrimal, jugal, squamosal, quadrate, palatine, ectopterygoid, and surangular. Pneumaticity is not present, however, in the nasal, postorbital, quadratojugal, pterygoid, or angular. Comparisons between Alioramus and other theropods (most importantly the closely related Tyrannosaurus) show that the cranial sinuses of Alioramus are modified to fill the long-snouted skull of this taxon, and that Alioramus has an extreme degree of cranial pneumaticity compared to other theropods, which may be the result of the juvenile status of the specimen, a difference in feeding style between Alioramus and other theropods, or passive processes. Based on these comparisons, we provide a revised terminology of cranial pneumatic structures and review the distribution, variation, and evolution of cranial pneumaticity within theropod dinosaurs. This review illustrates that most theropods possess a common "groundplan" in which the maxilla and lacrimal are pneumatized, and that various theropods modify this groundplan by pneumatizing numerous other bones of the skull. Tyrannosaurids are very pneumatic compared to other theropods, particularly in the development of extensive ectopterygoid, quadrate, and palatine sinuses, as well as a pneumatic invasion into the surangular. Tyrannosauroids seem to retain many cranial sinuses, such as the jugal and nasal recesses, which are primitive for coelurosaurs but lost or apomorphically modified in taxa more closely related to birds
Chadrolagus and Litolagus.
No full text76 pages : illustrations, map ; 26 cmLagomorphs from the late Eocene and Eocene-Oligocene transition of North America, apart from the abundant and fairly speciose Palaeolagus, are represented by some rare and enigmatic genera, including monospecific Chadrolagus and Litolagus, of uncertain infraordinal relationship. In this paper new specimens of lagomorphs from the Chadronian and Orellan of Montana and Wyoming are presented. They include Chadrolagus emryi from the early Chadronian of the Renova Formation, Beaverhead Basin (Montana), and the late Chadronian of the Dunbar Creek and Cook Ranch Formations (Montana), extending the stratigraphic range of this species to the entire Chadronian interval. Further, previously unreported material, originally collected by M.F. Skinner during his fieldwork in Wyoming (near the Chadronian-Orellan boundary in age), is described and figured. This includes an exquisitely preserved skull of Litolagus molidens, and Limitolagus roosevelti, gen. et sp. nov., represented by mandibular and dental material from the Chadronian-Orellan boundary. L. roosevelti shares many similarities in dental structure with Chadrolagus, but its size is close to Litolagus molidens. The information provided by newly described material and a revision of the type specimens and topotypic series of Chadrolagus emryi and Litolagus molidens allow for an extended diagnosis of these taxa and a preliminary phylogenetic analysis of Paleogene North American lagomorphs with Desmatolagus gobiensis as an outgroup. The skull of Litolagus molidens shows many derived characters: shortening of the palatal bridge and the reduction of its palatine portion, greater skull height, and an increase in the size of the auditory bullae. The greater basicranial angle and relatively wider choanae indicate increased cursorial adaptations. A cladistic analysis shows that there is no immediate ancestral relationship between Chadrolagus and Litolagus, and it supports an advanced phylogenetic position for Litolagus closer to Archaeolaginae, suggested by the cranial and dental morphology. Limitolagus is related closely to Chadrolagus and paraphyly of Palaeolagus is strongly suggested, due to a placement of P. burkei between Limitolagus and the clade composed of Archaeolagus + Litolagus
Myersiohyla from Cerro de la Neblina.
No full text63 pages : illustrations (some color) ; 26 cmTwo new species of Myersiohyla are described from the 1984-1985 Cerro de la Neblina Expedition in southern Venezuela, together with notes on the genus and a test of its monophyly, which has been challenged in recent studies. The inclusion of new sequences results in a monophyletic Myersiohyla that is better supported than in earlier analyses. One of the new species is similar to M. inparquesi, with which it has been confused previously. This newly described species has, like M. inparquesi, a tadpole with a dorsoventrally flattened body and the largest labial toothrow formula so far reported for anuran larvae (16/21). It differs from M. inparquesi in larval characters, adult coloration, and vocalization. The other new species is unique in having a color pattern composed of stellate melanophores over a greenish ground color. Comments on the holotype of M. loveridgei provide details overlooked in previous references to this rare species and stress the need to establish diagnostic characters that might differentiate it from M. aromatica. Furthermore, we report one specimen not assigned to any species from Huachamacary Tepui, only 25 km from the type locality of M. loveridgei. So far, all studied species of Myersiohyla have relatively large (2.8-3.2 mm), yolky ovarian eggs, a character state shared with several other frogs in Cophomantini (Hyloscirtus, Aplastodiscus, the Hypsiboas benitezi species group), and likely a plesiomorphic character state for the tribe. We report and illustrate the occurrence of a mental gland in some species of Myersiohyla and present a short discussion on odorous volatile secretions reported in some species of this genus. The following species are described or discussed herein: Myersiohyla chamaeleo new species, p. 8, M. neblinaria new species, p. 25, M. loveridgei (Rivero), p. 38, Myersiohyla species inquirenda, p. 40, and M. kanaima (Goin and Woodley), p. 42. Following the International Code of Zoological Nomenclature, the nominal type species of Myersiohyla is changed from Hyla inparquesi to Myersiohyla neblinaria (p. 42)
