Imaging evolution of the primate brain: the next frontier?

Evolution, as we currently understand it, strikes a delicate balance between animals' ancestral history and adaptations to their current niche. Similarities between species are generally considered inherited from a common ancestor whereas observed differences are considered as more recent evolution. Hence comparing species can provide insights into the evolutionary history. Comparative neuroimaging has recently emerged as a novel subdiscipline, which uses magnetic resonance imaging (MRI) to identify similarities and differences in brain structure and function across species. Whereas invasive histological and molecular techniques are superior in spatial resolution, they are laborious, post-mortem, and oftentimes limited to specific species. Neuroimaging, by comparison, has the advantages of being applicable across species and allows for fast, whole-brain, repeatable, and multi-modal measurements of the structure and function in living brains and post-mortem tissue. In this review, we summarise the current state of the art in comparative anatomy and function of the brain and gather together the main scientific questions to be explored in the future of the fascinating new field of brain evolution derived from comparative neuroimaging.

Hic est locus ubi mors gaudet succurrere vitae: the utility of morphologic disciplines in the study of cetaceans' pathology.

The role played by morphologic disciplines and investigations in the study of the causes of death as well as of the pathology of cetaceans is of paramount relevance. In this respect, an absolutely paradigmatic example is that represented by Morbillivirus infections, which during the last 25 years have caused a number of dramatic epidemics among free-ranging pinnipeds and cetaceans worldwide.

Anatomy of large animal spines and its comparison to the human spine: a systematic review.

Animal models have been commonly used for in vivo and in vitro spinal research. However, the extent to which animal models resemble the human spine has not been well known. We conducted a systematic review to compare the morphometric features of vertebrae between human and animal species, so as to give some suggestions on how to choose an appropriate animal model in spine research. A literature search of all English language peer-reviewed publications was conducted using PubMed, OVID, Springer and Elsevier (Science Direct) for the years 1980-2008. Two reviewers extracted data on the anatomy of large animal spines from the identified articles. Each anatomical study of animals had to include at least three vertebral levels. The anatomical data from all animal studies were compared with the existing data of the human spine in the literature. Of the papers retrieved, seven were included in the review. The animals in the studies involved baboon, sheep, porcine, calf and deer. Distinct anatomical differences of vertebrae were found between the human and each large animal spine. In cervical region, spines of the baboon and human are more similar as compared to other animals. In thoracic and lumbar regions, the mean pedicle height of all animals was greater than the human pedicles. There was similar mean pedicle width between animal and the human specimens, except in thoracic segments of sheep. The human spinal canal was wider and deeper in the anteroposterior plane than any of the animals. The mean human vertebral body width and depth were greater than that of the animals except in upper thoracic segments of the deer. However, the mean vertebral body height was lower than that of all animals. This paper provides a comprehensive review to compare vertebrae geometries of experimental animal models to the human vertebrae, and will help for choosing animal model in vivo and in vitro spine research. When the animal selected for spine research, the structural similarities and differences found in the animal studies must be kept in mind.

New insights into dinosaur jaw muscle anatomy.

Jaw muscles are key components of the head and critical to testing hypotheses of soft-tissue homology, skull function, and evolution. Dinosaurs evolved an extraordinary diversity of cranial forms adapted to a variety of feeding behaviors. However, disparate evolutionary transformations in head shape and function among dinosaurs and their living relatives, birds and crocodylians, impair straightforward reconstructions of muscles, and other important cephalic soft tissues. This study presents the osteological correlates and inferred soft tissue anatomy of the jaw muscles and relevant neurovasculature in the temporal region of the dinosaur head. Hypotheses of jaw muscle homology were tested across a broad range archosaur and sauropsid taxa to more accurately infer muscle attachments in the adductor chambers of non-avian dinosaurs. Many dinosaurs likely possessed m. levator pterygoideus, a trait shared with lepidosaurs but not extant archosaurs. Several major clades of dinosaurs (e.g., Ornithopoda, Ceratopsidae, Sauropoda) eliminated the epipterygoid, thus impacting interpretations of m. pseudotemporalis profundus. M. pseudotemporalis superficialis most likely attached to the caudoventral surface of the laterosphenoid, a trait shared with extant archosaurs. Although mm. adductor mandibulae externus profundus and medialis likely attached to the caudal half of the dorsotemporal fossa and coronoid process, clear osteological correlates separating the individual bellies are rare. Most dinosaur clades possess osteological correlates indicative of a pterygoideus ventralis muscle that attaches to the lateral surface of the mandible, although the muscle may have extended as far as the jugal in some taxa (e.g., hadrosaurs, tyrannosaurs). The cranial and mandibular attachments of mm adductor mandibulae externus superficialis and adductor mandibulae posterior were consistent across all taxa studied. These new data greatly increase the interpretive resolution of head anatomy in dinosaurs and provide the anatomical foundation necessary for future analyses of skull function and evolution in an important vertebrate clade.

Fusión de la epífisis esternal de la clavícula en relación con la edad. Aplicaciones en la estimación forense de la edad / Fusion of clavicle sternal epiphyses in relation to age. Aplications in forensic estimation of age

Dentro de la estimación forense de la edad, las recomendaciones del AGFAD establecen la práctica de estudios de radiología de la clavícula para el diagnóstico de la edad en la franja entre los 18 y 21 años de edad. Se presenta un estudio sobre una muestra de 123 radiografías digitales de tórax de sujetos entre 5 y 75 años de edad en las que se ha analizado el estado de fusión de la epífisis esternal de la clavícula. En este estudio la edad mínima a la que se ha podido valorar la existencia de un estado de fusión completa (estadios 4 y 5 de Schmeling) ha sido de 19,7 años. Se analiza la bibliografía actualizada sobre este fenómeno y se apuntan una serie de sugerencias adicionales a las propuestas por AGFAD

In 2000 the AGFAD published their recommendations about forensic age estimations. They recommended an X ray of the clavicle (collar bone) in cases of subjects between 18 and 21 years of age. We present a study on stages of fusion of clavicle sternal epiphyses in a 123 digital X-rays from a population sample between 5 and 75 years of age. In our research minimum age at which complete fusion was achived (stages 4 or 5 in Schmeling method) has been 19,7 years of chronological age. A review of the medico legal literature about age estimation based on sternal end of the clavicle has been included. It´s pointed out that forensic experts should bear in mind some suggestions when applying AGFAD recommendations to obtain an age estimation based in clavicle X-rays

TRIBUTE: In Goethe's Wake: Marvalee Wake's conceptual contributions to the development and evolution of a science of morphology.

De-crying the typological approach in much of the teaching of morphology, from the outset of her career Marvalee Wake advocated a synthetic, mechanistic and pluralistic developmental and evolutionary morphology. In this short essay, I do not evaluate Wake's contributions to our knowledge of the morphology of caecilians, nor her contributions to viviparity, both of which are seminal and substantive, nor do I examine her role as mentor, supervisor and collaborator, but assess her broader conceptual contributions to the development and evolution of morphology as a science. One of the earliest morphologists to take on board the concept of constraint, she viewed constraint explicitly in relation to adaptation and diversity. Her approach to morphology as a science was hierarchical - measure form and function in a phylogenetic context; seek explanations at developmental, functional, ecological, evolutionary levels of the biological hierarchy; integrate those explanations to the other levels. The explanatory power of morphology thus practised allows morphology to inform evolutionary biology and evolutionary theory, and paves the way for the integrative biology Wake has long championed.

Phylogeny and evo-devo: characters, homology, and the historical analysis of the evolution of development.

The concept of homology continues to attract more and more commentary. In systematic and evolutionary biology the meaning of homology as synapomorphic similarity inherited from a common ancestor has gained wide acceptance over the last three or four decades. In recent years, however, developmental biologists, in particular, have argued for a new approach to, and new definition for, homology that revolves around the desire to make it more process-oriented and more mechanistic. These efforts raise questions about the relationship between developmental and evolutionary biology as well as how the evolution of development is to be studied. It is argued in this paper that this new approach to homology seemingly decouples developmental biology from the study of the evolution of development rather than to facilitate that study. In contrast, applying the notion of historical, phylogenetic homology to developmental data is inherently comparative and therefore evolutionary.

The supramedullary neurons of fish: present status and goals for the future.

In this paper, we report the recent findings on supramedullary neurons of fish, with special attention to the studies, which made the nature of this neuronal system clear. Indeed, immunohistochemical, physiological and neuroanatomical data, taken together, point out that this neuronal system is a component of the autonomic nervous system. New goals have been opened by the more recent research, especially in comparative neurobiology. Indeed, the supramedullary neurons, owing to some characteristics, like the DNA endoreplication, the large size, the accessible localization and the relationship with glial cells, may be utilised as a very suitable model in several fields of neurobiology of vertebrates, such as molecular genetic, electrophysiology, nervous system ageing, glial-neuron interactions.

The emerging conceptual framework of evolutionary developmental biology.

Over the last twenty years, there has been rapid growth of a new approach to understanding the evolution of organismic form. This evolutionary developmental biology, or 'evo-devo', is focused on the developmental genetic machinery that lies behind embryological phenotypes, which were all that could be studied in the past. Are there any general concepts emerging from this new approach, and if so, how do they impact on the conceptual structure of traditional evolutionary biology? In providing answers to these questions, this review assesses whether evo-devo is merely filling in some missing details, or whether it will cause a large-scale change in our thinking about the evolutionary process.