Covariation of proximal finger and toe phalanges in Homo sapiens: A novel approach to assess covariation of serially corresponding structures.

Objectives: As hands and feet are serially repeated corresponding structures in tetrapods, the morphology of fingers and toes is expected to covary due to a shared developmental origin. The present study focuses on the covariation of the shape of proximal finger and toe phalanges of adult Homo sapiens to determine whether covariation is different in the first ray relative to the others, as its morphology is also different.

Material And Methods: Proximal phalanges of 76 individuals of unknown sex (Muséum national d'Histoire naturelle, Paris, and the Natural History Museum, London) were digitized using a surface scanner.

Ancient DNA of the pygmy marmoset type specimen (Spix, 1823) resolves a taxonomic conundrum.

The pygmy marmoset, the smallest of the anthropoid primates, has a broad distribution in Western Amazonia. Recent studies using molecular and morphological data have identified two distinct species separated by the Napo and Solimões-Amazonas rivers. However, reconciling this new biological evidence with current taxonomy, i.

Scythes, sickles and other blades: defining the diversity of pectoral fin morphotypes in Pachycormiformes.

The traditional terminology of 'scythe' or 'sickle' shaped is observed to be flawed as an effective descriptor for pectoral fin shape in pachycormids. The diversity of pachycormid pectoral fin shapes is assessed across the 14 recognised genera that preserve complete pectoral fins, and improved terms are defined to more effectively describe their form, supported by anatomical observation and aspect ratio analysis of individual fins, and corroborated by landmark analysis. Three clear and distinct pectoral fin structural morphotypes emerge (falceform, gladiform, falcataform), reflecting a diversity of pachycormid lifestyles throughout the Mesozoic, from agile pursuit predator to slow-cruising suspension feeder.

Femoral morphology of sciuromorph rodents in light of scaling and locomotor ecology.

Sciuromorph rodents are a monophyletic group comprising about 300 species with a body mass range spanning three orders of magnitude and various locomotor behaviors that we categorized into arboreal, fossorial and aerial. The purpose of this study was to investigate how the interplay of locomotor ecology and body mass affects the morphology of the sciuromorph locomotor apparatus. The most proximal skeletal element of the hind limb, i.

Homeotic transformations reflect departure from the mammalian 'rule of seven' cervical vertebrae in sloths: inferences on the Hox code and morphological modularity of the mammalian neck.

Background: Sloths are one of only two exceptions to the mammalian 'rule of seven' vertebrae in the neck. As a striking case of breaking the evolutionary constraint, the explanation for the exceptional number of cervical vertebrae in sloths is still under debate. Two diverging hypotheses, both ultimately linked to the low metabolic rate of sloths, have been proposed: hypothesis 1 involves morphological transformation of vertebrae due to changes in the Hox gene expression pattern and hypothesis 2 assumes that the Hox gene expression pattern is not altered and the identity of the vertebrae is not changed.

Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation.

Background: Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs.

Correction: Neither slim nor fat: estimating the mass of the dodo (, Aves, Columbiformes) based on the largest sample of dodo bones to date.

[This corrects the article DOI: 10.7717/peerj.4110.

Neither slim nor fat: estimating the mass of the dodo (, Aves, Columbiformes) based on the largest sample of dodo bones to date.

The dodo () might be the most enigmatic bird of all times. It is, therefore, highly remarkable that no consensus has yet been reached on its body mass; previous scientific estimates of its mass vary by more than 100%. Until now, the vast amount of bones stored at the Natural History Museum in Mauritius has not yet been studied morphometrically nor in relation to body mass.

Trabecular architecture in the forelimb epiphyses of extant xenarthrans (Mammalia).

Background: Bone structure has a crucial role in the functional adaptations that allow vertebrates to conduct their diverse lifestyles. Much has been documented regarding the diaphyseal structure of long bones of tetrapods. However, the architecture of trabecular bone, which is for instance found within the epiphyses of long bones, and which has been shown experimentally to be extremely plastic, has received little attention in the context of lifestyle adaptations (virtually only in primates).

Geometric morphometric analysis of intratrackway variability: a case study on theropod and ornithopod dinosaur trackways from Münchehagen (Lower Cretaceous, Germany).

A profound understanding of the influence of trackmaker anatomy, foot movements and substrate properties is crucial for any interpretation of fossil tracks. In this case study we analyze variability of footprint shape within one large theropod (T3), one medium-sized theropod (T2) and one ornithopod (I1) trackway from the Lower Cretaceous of Münchehagen (Lower Saxony, Germany) in order to determine the informativeness of individual features and measurements for ichnotaxonomy, trackmaker identification, and the discrimination between left and right footprints. Landmark analysis is employed based on interpretative outline drawings derived from photogrammetric data, allowing for the location of variability within the footprint and the assessment of covariation of separate footprint parts.

The Quadratojugal of Eryops studied by computed tomography and the morphological variability of foramina and canals in the quadratojugal of basal tetrapods.

With respect to its large size and abundance, Eryops is an important representative of Permo-Carboniferous basal tetrapods and one of the best-known large temnospondyl amphibians of this period. This taxon forms a significant component of the Early Permian tetrapod fauna of Texas and New Mexico and here we describe a new record of skull remains, the first one from Brushy Creek (30 km northeast of Seymour) in Texas (Petrolia Formation, Wichita Group; Lower Permian - lower Artinskian). Our material, found in 2015, consists of a left nasal, a jaw fragment (premaxilla or maxilla), left quadratojugal fragments, and a partial left mandible.

Is LB1 diseased or modern? A review of the proposed pathologies.

The fossil remains of Homo floresiensis have been debated extensively over the past few years. This paper gives a review of the various pathologies ascribed to LB1, the type specimen of H. floresiensis, and associated individuals.