Sophie Sanchez

Uppsala University | UU · Department of Organismal Biology

Detailed histological analyses are desirable for zebrafish mutants that are models for human skeletal diseases, but traditional histological techniques are limited to two-dimensional thin sections with orientations highly dependent on careful sample preparation. On the other hand, techniques that provide three-dimensional (3D) datasets including µC...

The origin and early diversification of jawed vertebrates involved major changes to skeletal and soft anatomy. Skeletal transformations can be examined directly by studying fossil stem gnathostomes; however, preservation of soft anatomy is rare. We describe the only known example of a three-dimensionally mineralized heart, thick-walled stomach, and...

The Cretaceous–Palaeogene mass extinction around 66 million years ago was triggered by the Chicxulub asteroid impact on the present-day Yucatán Peninsula1,2. This event caused the highly selective extinction that eliminated about 76% of species3,4, including all non-avian dinosaurs, pterosaurs, ammonites, rudists and most marine reptiles. The timin...

Significance Some lineages of organisms have undergone major evolutionary radiations, while others have not. Establishing why is a central goal of evolutionary research. Whole-genome duplication (WGD) is often proposed as having caused the spectacular evolutionary radiation of teleost fishes. However, due to the absence of genetic data for fossil s...

Teleost fishes comprise one-half of all vertebrate species and possess a duplicated genome. This whole-genome duplication (WGD) occurred on the teleost stem lineage in an ancient common ancestor of all living teleosts and is hypothesized as a trigger of their exceptional evolutionary radiation. Genomic and phylogenetic data indicate that WGD occurr...

The Cretaceous-Paleogene (KPg) mass extinction ~66 million years ago (Ma) was triggered by the Chicxulub impact on the present-day Yucatán Peninsula. This event caused the extinction of circa 76% of species, including all non-avian dinosaurs, and represents one of the most selective extinctions to date. The timing of the impact and its aftermath ha...

Thyestiids are a group of osteostracans (sister‐group to jawed vertebrates) ranging in time from the early Silurian to Middle Devonian. Tremataspis is unique among thyestiids in having a continuous mesodentine and enameloid cover on its dermal elements, and an embedded pore‐canal system divided into lower and upper parts by a perforated septum. The...

The production of blood cells (haematopoiesis) occurs in the limb bones of most tetrapods but is absent in the fin bones of ray-finned fish. When did long bones start producing blood cells? Recent hypotheses suggested that haematopoiesis migrated into long bones prior to the water-to-land transition and protected newly-produced blood cells from har...

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically most basal stem osteichthyan, visualized by synchrotron microtomography, reveals a developmental relationship between teeth and dermal odontodes that is not evident from the adult morphology. The earliest odontodes ar...

Growth plate and articular cartilage constitute a single anatomical entity early in development but later separate into two distinct structures by the secondary ossification center (SOC). The reason for such separation remains unknown. We found that evolutionarily SOC appears in animals conquering the land - amniotes. Analysis of the ossification p...

Growth plate and articular cartilage constitute a single anatomical entity early in development but later separate into two distinct structures by the secondary ossification center (SOC). The reason for such separation remains unknown. We found that evolutionarily SOC appears in animals conquering the land - amniotes. Analysis of the ossification p...

Growth plate and articular cartilage constitute a single anatomical entity early in development, but later separate into two distinct structures by the secondary ossification center (SOC). The reason for such separation remains unknown. We found that evolutionarily SOC appears in animals conquering the land - amniotes. Analysis of ossification patt...

Ontogenetic data obtained by synchrotron microtomography of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically basalmost stem osteichthyan, reveal developmental relationships between teeth and ornament that are not obvious from the adult morphology. The earliest odontodes are two longitudinal foun...

Tetrapod life on land was the result of a lengthy process, the final steps of which resulted in full independence of amniotic tetrapods from the aquatic environment. Developmental strategies, including growth rate and the attainment of sexual maturity, played a major role in this transition. Early amniotes, such as Ophiacodon, tended to reach sexua...

Osteocytes, cells embedded within the bone mineral matrix, inform on key aspects of vertebrate biology. In particular, a relationship between volumes of the osteocytes and bone growth and/or genome size has been proposed for several tetrapod lineages. However, the variation in osteocyte volume across different scales is poorly characterised, and mo...

Studies on living turtles have demonstrated that shells are involved in the resistance to hypoxia during apnea via bone acidosis buffering; a process which is complemented with cutaneous respiration, transpharyngeal and cloacal gas exchanges in the soft-shell turtles. Bone acidosis buffering during apnea has also been identified in crocodylian oste...

Osteocytes, cells embedded within the bone mineral matrix, inform on key aspects of vertebrate biology. In particular, a relationship between volumes of the osteocytes and bone growth and/or genome size has been proposed for several tetrapod lineages. However, the variation in osteocyte volume across different scales is poorly characterised, and mo...

The growth of long bones occurs in narrow discs of cartilage, called growth plates that provide a continuous supply of chondrocytes subsequently replaced by newly formed bone tissue. These growth plates are sandwiched between the bone shaft and a more distal bone structure called the secondary ossification center (SOC). We have recently shown that...

Hyneria lindae is one of the largest Devonian sarcopterygians. It was found in the Catskill Formation (late Famennian) of Pennsylvania, USA. The current study focuses on the palaeohistology of the humerus of this tristichopterid and supports a low ossification rate and a late ossification onset in the appendicular skeleton. In addition to anatomica...

Whether hydroxyapatite (HA) orientation in fossilised bone samples can be non-destructively retrieved and used to determine the arrangement of the bone matrix and the location of muscle attachments (entheses), is a question of high relevance to palaeontology, as it facilitates a detailed understanding of the (micro-)anatomy of extinct species with...

Archaeopteryx is an iconic fossil taxon with feathered wings from the Late Jurassic of Germany that occupies a crucial position for understanding the early evolution of avian flight. After over 150 years of study, its mosaic anatomy unifying characters of both non-flying dinosaurs and flying birds has remained challenging to interpret in a locomoto...

Fossils of juvenile Mesozoic birds provide insight into the early evolution of avian development, however such fossils are rare. The analysis of the ossification sequence in these early-branching birds has the potential to address important questions about their comparative developmental biology and to help understand their morphological evolution...

There are two types of dermal skeletons in jawed vertebrates: placoderms and osteichthyans carry large bony plates (macromery), whereas chondrichthyans and acanthodians are covered by small scales (micromery). Fin spines are one of the last large dermal structures found on micromeric taxa and offer a potential source of histology and morphology tha...

Thin section (S2368) of a dermal plate of Romundina, deposited at the Natural History Museum of Stockholm. Arrows mark the cell lacunae and arrowheads mark the dentine tubules. Note the different colors of the outer layer and the inner layer, both of which have dentine tubules and cell lacunae. (TIF)

Palaeospondylus gunni Traquair, 1890 is an enigmatic Devonian vertebrate whose taxonomic affinities have been debated since it was first described. Most recently, Palaeospondylus has been identified as a stem-group hagfish (Myxinoidea). However, one character questioning this assignment is the presence of three semicircular canals in the otic region of...

In order to understand the ecological dimension of the fish-tetrapod transition, which occurred within the tetrapod stem group during the Devonian Period (419-359 million years ago), we need life-history data from transitional forms. Only recently have serious attempts begun to utilize limb-bone histology as a source of such data. Here we present h...

Recently, attempts have been made to utilize limb-bone histology as a source of data for understanding the ecological dimension of the fish-tetrapod transition. Here we present histological life history data from a humerus (ANSP 21483) of Hyneria lindae, a fish member of the tetrapod stem group from the Late Devonian Catskill Formation (Pennsylvani...

The numerous cushion-shaped tooth-bearing plates attributed to the stem group osteichthyan Lophosteus superbus, which are argued here to represent an early form of the osteichthyan inner dental arcade, display a previously unknown and presumably primitive mode of tooth shedding by basal hard tissue resorption. They carry regularly spaced, recumbent...

Placoderms are considered as the first jawed vertebrates and constitute a paraphyletic group in the stem-gnathostome grade. The acanthothoracid placoderms are among the phylogenetically most basal and morphologically primitive gnathostomes, but their neurocranial anatomy is poorly understood. Here we present a near-complete three-dimensional skull...

Anatomical abbreviations used in the figures. (XLS)

Romundina stellina, MNHN.F.CPW1, filling of the internal structures and rotation around the specimen. (0400–0750 (Nouveau).avi: Maya Autodesk; 25 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of the endocranial cavity. olaf_002: Mimics; 5,28 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of the right inner ear. olaf_006: Mimics; 8,61 MB. (AVI)

Remark concerning the myodomes and the extrinsic muscles in the orbit. (DOC)

Romundina stellina, MNHN.F.CPW1, complete run-through (contrasted) (complete_runthrough_contrasted_avi.avi; 19,8 MB). ImageJ. (AVI)

Skull of Romundina stellina Ørvig, 1975. Specimen MNHN.F.CPW6. A. Dorsal view. B. Left lateral view. C. anterior view. D. posterior view. Scale bar 10 mm. Notice in B the light in the foramen for the pituitary vein indicating that it opens in a canal opening in the right orbit. (TIF)

Romundina stellina, MNHN.F.CPW1, rotation of the dermal bone and perichondral bone vasculature (vertical_rotation.avi; VG StudioMax, SS and PT). (AVI)

Romundina stellina, MNHN.F.CPW1, apparition of the 3D model emerging from below the photograph of the actual specimen. The dermal skull roof opens to reveal the internal perichondral structures. 0001–0125 (nouveau).avi: Maya Autodesk; 3,88 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation around the internal perichondral bone ossification, revealing the lace pattern. 0125–400 (nouveau).avi: Maya Autodesk; 21,3 MB. (AVI)

Romundina stellina, MNHN.F.CPW1,: rotation of model with external perichondral bone opaque. olaf_004; Mimics;16,9 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of model with external perichondral bone semitransparent. olaf_005; Mimics;16,9 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of left inner ear. olaf_007; Mimics; 8,35 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of opaque dermal bone of the skull roof. olaf_012; Mimics; 14 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, endocranial cavity filled plus cranial nerves plus part of the sensory line system. olaf_020: Mimics; 7,73 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of external perichondral bone semitransparent with internal vacularization opaque. olaf_021; Mimics; 12,1 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of endocranial cavity, inner ears and right endolymphatic duct. olaf_019; Mimics; 10,5 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of model without external perichondral and dermal bone. olaf_003; Mimics;11,4 MB. (AVI)

Romundina stellina, MNHN.F.CPW1, rotation of dermal bone vasculature, nerves, arteries and veins. olaf_010; Mimics; 12,5 MB. (AVI)