Bone metabolism and evolutionary origin of osteocytes: Novel application of FIB-SEM tomography.

Lacunae and canaliculi spaces of osteocytes are remarkably well preserved in fossilized bone and serve as an established proxy for bone cells. The earliest bone in the fossil record is acellular (anosteocytic), followed by cellular (osteocytic) bone in the jawless relatives of jawed vertebrates, the osteostracans, about 400 million years ago. Virtually nothing is known about the physiological pressures that would have initially favored osteocytic over anosteocytic bone.

Rarity of congenital malformation and deformity in the fossil record of vertebrates - A non-human perspective.

Objective: A malformed pectoral joint of the middle Devonian antiarch fish Asterolepis ornata is described, and a survey of congenital malformations in the fossil record is provided.

Materials: The specimen of A. ornata (MB.

Do Meristic Characters Used in Phylogenetic Analysis Evolve in an Ordered Manner?

The use of ordered characters in phylogenetic analysis has been inconsistent throughout the history of phylogenetic inference. It has become more widespread in recent years, and some have advocated that all characters representing continuous or meristic traits should be ordered as a matter of course. Here, using the example of dental evolution, we examine two factors that may impact on whether meristic characters actually evolve in an ordered manner: the regulatory hierarchy governing the development of teeth that allows large sections of the entire tooth row to be suppressed in a single transition and regionalization of the tooth row where different modules have a degree of independence in their evolution.

Histological skeletochronology indicates developmental plasticity in the early Permian stem lissamphibian .

is a small-bodied early Permian amphibamiform, a clade of temnospondyl amphibians regarded by many workers to be on the lissamphibian stem. Most studies of this taxon have focused solely on its anatomy, but further exploration of other aspects of its paleobiology, such as developmental patterns, is critical for a better understanding of the early evolutionary history of lissamphibians. Here, we present a histological analysis of growth patterns in that utilizes 60 femora, the largest sample size for any Paleozoic tetrapod.

Retention of fish-like odontode overgrowth in Permian tetrapod dentition supports outside-in theory of tooth origins.

Teeth are often thought of as structures that line the margins of the mouth; however, tooth-like structures called odontodes are commonly found on the dermal bones of many Palaeozoic vertebrates including early jawless fishes. 'Odontode' is a generalized term for all tooth-like dentine structures that have homologous tissues and development. This definition includes true teeth and the odontodes of early 'fishes', which have been recently examined to gain new insights into the still unresolved origin of teeth.

Permian metabolic bone disease revealed by microCT: Paget's disease-like pathology in vertebrae of an early amniote.

Bone remodeling is an essential physiological process in growth and healing. In modern systems deviations from normal bone physiology in the form of pathologies aid in the understanding of normal bone metabolism. Here we use external morphology and X-ray microtomography to diagnose and describe a metabolic bone disease in an amniote from the early Permian.

Triassic Cancer-Osteosarcoma in a 240-Million-Year-Old Stem-Turtle.

This case study documents osteosarcoma in 240-million-year-old stem-turtle, which suggests that cancer is not a modern physiological defect.

Histological analysis of post-eruption tooth wear adaptations, and ontogenetic changes in tooth implantation in the acrodontan squamate .

Teeth have been a focus of research in both extinct and extant taxa alike; a significant portion of dental literature is concerned with dental patterning and replacement. Most non-mammalian vertebrates continuously replace their dentition but an anomalous group of squamates has forgone this process in only having one tooth generation; these squamates all have apically implanted teeth, a condition known as acrodonty. Acrodont dentition and various characteristics attributed to it, including a lack of replacement, have often been defined ambiguously.

The Permian reptile Opisthodontosaurus carrolli: a model for acrodont tooth replacement and dental ontogeny.

Continuous tooth replacement is common for tetrapods, but some groups of acrodont lepidosaurs have lost the ability to replace their dentition (monophyodonty). Acrodonty, where the tooth attaches to the apex of the jawbone, is an unusual form of tooth attachment that has been associated with the highly autapomorphic condition of monophyodonty. Beyond Lepidosauria, very little is known about the relationship between acrodonty and monophyodonty in other amniotes.

Histological characterization of denticulate palatal plates in an Early Permian dissorophoid.

Denticles are small, tooth-like protrusions that are commonly found on the palate of early tetrapods. Despite their widespread taxonomic occurrence and similar external morphology to marginal teeth, it has not been rigorously tested whether denticles are structurally homologous to true teeth with features such as a pulp cavity, dentine, and enamel, or if they are bony, tooth-like protrusions. Additionally, the denticles are known to occur not only on the palatal bones but also on a mosaic of small palatal plates that is thought to have covered the interpterygoid vacuities of temnospondyls through implantation in a soft tissue covering; however, these plates have never been examined beyond a simple description of their position and external morphology.

Ontogenetic Change in the Temporal Region of the Early Permian Parareptile Delorhynchus cifellii and the Implications for Closure of the Temporal Fenestra in Amniotes.

A juvenile specimen of Delorhynchus cifellii, collected from the Early Permian fissure-fill deposits of Richards Spur, Oklahoma, permits the first detailed study of cranial ontogeny in this parareptile. The specimen, consisting of a partially articulated skull and mandible, exhibits several features that identify it as juvenile. The dermal tuberosities that ornament the dorsal side and lateral edges of the largest skull of D.