Related Experiment Video
Updated: Jun 29, 2026
09:30
Using Avian Skin Explants to Study Tissue Patterning and Organogenesis
Published on: September 15, 2023
Feather-like development of Triassic diapsid skin appendages
Sebastian Voigt1, Michael Buchwitz, Jan Fischer
1Geologisches Institut, Technische Universität Bergakademie Freiberg, Bernhard-von-Cotta-Strasse 2, 09599, Freiberg, Germany. s.voigt@geo.tu-freiberg.de
Die Naturwissenschaften
|October 7, 2008
Summary
Recent sauropsid skin appendages, like feathers, develop from follicles. New analysis of Longisquama insignis shows its unique dorsal projections formed via a feather-like developmental process, not scales.
Area of Science:
- Paleontology
- Evolutionary Biology
- Developmental Biology
Background:
- Feathers are unique sauropsid skin appendages that develop from follicles and exhibit hierarchical branching.
- Fossilized integuments of Mesozoic diapsids are often debated as potential feather homologues.
- The dorsal skin projections of Longisquama insignis, a Triassic diapsid, are particularly controversial in this regard.
Observation:
- New fossil finds and comparisons with existing material reveal Longisquama's appendages possess a single-branched internal frame.
- This frame is encased by a flexible outer membrane.
- The structure does not align with typical feather or scale morphology.
Findings:
- Longisquama's appendages exhibit a two-stage developmental process.
- This process is analogous to feather development.
- The findings challenge existing classifications of these Mesozoic integuments.
Implications:
- The study suggests Longisquama's appendages are neither true feathers nor scales.
- This represents an early instance of evolutionary plasticity in sauropsid integument development.
- The findings contribute to understanding the early evolution of skin appendages in reptiles and birds.
Related Concept Videos
01:09Changes in the Appendicular Skeleton with Age
The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
01:11Papillary Dermis
Dermis
The dermis might be considered the "core" of the integumentary system, as distinct from the epidermis and hypodermis. It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that comprise an interconnected mesh of elastin and collagenous fibers, produced by fibroblasts.
Papillary Layer
The papillary layer is made of loose, areolar connective tissue, which means the collagen and...
The dermis might be considered the "core" of the integumentary system, as distinct from the epidermis and hypodermis. It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that comprise an interconnected mesh of elastin and collagenous fibers, produced by fibroblasts.
Papillary Layer
The papillary layer is made of loose, areolar connective tissue, which means the collagen and...
01:54Convergent Evolution
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.The structures that arise from convergent evolution are called analogous structures. They are similar in function even if they are dissimilar in structure. Further, structures can be analogous while also...
01:16Accessory Structures of the Skin: Hair and Hair Follicles
Hair and hair follicles are integral components of the integumentary system. Hair is a filamentous structure composed mainly of a protein called keratin. It is found on the surface of the skin throughout the body, except for areas such as the palms of the hands and soles of the feet.
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Hair strands originate at the epidermal penetration called the hair follicle. The hair shaft is the part...
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Hair strands originate at the epidermal penetration called the hair follicle. The hair shaft is the part...
01:23Surface Appendages of Archaea
Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, and motility. Among these appendages, pili and archaella stand out for their distinct morphologies and functionalities, enabling archaea to thrive in diverse and often extreme environments.Pili: Adhesion and Biofilm FormationPili are filamentous structures assembled from pilin protein subunits, primarily contributing to adhesion and biofilm...
01:30Neurulation
Neurulation is the embryological process which forms the precursors of the central nervous system and occurs after gastrulation has established the three primary cell layers of the embryo: ectoderm, mesoderm, and endoderm. In humans, the majority of this system is formed via primary neurulation, in which the central portion of the ectoderm—originally appearing as a flat sheet of cells—folds upwards and inwards, sealing off to form a hollow neural tube. As development proceeds, the anterior...