Development of the dermal skeleton in Alligator mississippiensis (Archosauria, Crocodylia) with comments on the homology of osteoderms

  title={Development of the dermal skeleton in Alligator mississippiensis (Archosauria, Crocodylia) with comments on the homology of osteoderms},
  author={Matthew K. Vickaryous and Brian K. Hall},
  journal={Journal of Morphology},
The dermal skeleton (= exoskeleton) has long been recognized as a major determinant of vertebrate morphology. Until recently however, details of tissue development and diversity, particularly among amniotes, have been lacking. This investigation explores the development of the dermatocranium, gastralia, and osteoderms in the American alligator, Alligator mississippiensis. With the exception of osteoderms, elements of the dermal skeleton develop early during skeletogenesis, with most initiating… 
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Osteoderms of Simosuchus clarki (Crocodyliformes: Notosuchia) from the Late Cretaceous of Madagascar
The anatomy, arrangement, and histology of the osteoderms of S. clarki are described, and comments on the phylogenetic and functional importance of these structures are provided, and several new morphological characters are described.
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Comparative development of the crocodylian interclavicle and avian furcula, with comments on the homology of dermal elements in the pectoral apparatus.
  • M. Vickaryous, B. Hall
  • Biology
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2010
It is concluded that the interclavicle is equally parsimonious as a homolog of the furcula during embryonic development in Alligator mississippiensis and Gallus gallus.
Armored geckos: A histological investigation of osteoderm development in Tarentola (Phyllodactylidae) and Gekko (Gekkonidae) with comments on their regeneration and inferred function
It is proposed that osteoderms serve roles in defense against combative prey and intraspecific aggression, along with anti‐predation functions in gekkotan lizards sensu lato.
The histological structure of glyptosaurine osteoderms (Squamata: Anguidae), and the problem of osteoderm development in squamates
The structural and histological features of glyptosaurine osteoderms were described in order to reconstruct their developmental pattern and further document the degree of homology that could exist between vertebrate integumentary skeletons.
Dermal Armor Histology of Saltasaurus loricatus, an Upper Cretaceous Sauropod Dinosaur from Northwest Argentina
The first unambiguous evidence of the presence of osteoderms in sauropod dinosaurs came from the discovery of Saltasaurus loricatus, a titanosaur from the Upper Cretaceous of Argentina. The dermal
On the homology of crocodylian post-dentary bones and their macroevolution throughout Pseudosuchia.
Embryological and paleontological data indicates that most perifenestral centers are involved in the origin of the prearticular of non-mesoeucrocodylian pseudosuchians, bolstering the idea that the coronoid and the articular of Crocodylia are not completely homologous to those of other diapsids.
Ontogeny of the skull of the Black Caiman (Melanosuchus niger) (Crocodylia: Alligatoridae)
We describe the formation of the chondrocranium and the ossification pattern of the skull of the Black Caiman (Melanosuchus niger (Spix, 1825)). The embryos were cleared and double-stained with
First Evidence of Dinosaurian Secondary Cartilage in the Post-Hatching Skull of Hypacrosaurus stebingeri (Dinosauria, Ornithischia)
This study reveals the first evidence of “avian” secondary cartilage in a non-avian dinosaur, and pushes the origin of this "avian" tissue deep into dinosaurian ancestry, suggesting the creation of the more appropriate term “dinosaurian’ secondary Cartilage.


Osteology and skeletal development of Apalone spinifera (Reptilia: Testudines: Trionychidae)
  • C. Sheil
  • Biology
    Journal of morphology
  • 2003
The adult skeleton of the spiny softshell turtle, Apalone spinifera (Testudines: Trionychidae), is described and this description forms a basis of comparison for the embryonic skeleton and its ontogenesis.
Osteoderm morphology and development in the nine‐banded armadillo, Dasypus novemcinctus (Mammalia, Xenarthra, Cingulata)
The absence of cartilage precursors indicates that osteoderms are dermal elements, possibly related to the all‐encompassing vertebrate dermal skeleton (exoskeleton), and instead is comparable with intramembranously derived elements of the skull.
Postparietal and prehatching ontogeny of the supraoccipital in Alligator mississippiensis (Archosauria, Crocodylia)
The first record of the postparietal bone of Alligator mississippiensis, documented by transverse histological sections, is presented. It is the first evidence of the presence of this bone within
Studies on skeleton formation in reptiles. v. Patterns of ossification in the skeleton of Alligator mississippiensis DAUDIN (Reptilia, Crocodylia)
Ontogenetic repatterning in the ossification of the axial skeleton is discussed as it bears on the serial homology of dorsal ribs, sacral ribs and caudal ribs (transverse processes).
Chondroid bone on the upper pharyngeal jaws and neurocranial base in the adult fish Astatotilapia elegans.
Serial cross sections of several adult specimens of the cichlid Astatotilapia elegans were used to investigate the fate and structure of the chondroid bone on the articulation between upper pharyngeal jaws and neurocranial base, finding cellular bone found at the basal margin does not result from endochondral replacement of the latter but from dermal ossification projecting from the marrow cavity.
Osteoderms in Anurans
It is suggested that the term dermal scale be restricted to the bony scale of fishes and caecilians, and osteoderms be used to denote the dermal scutes of anurans and reptiles.
Development of the dentition in Alligator mississippiensis: upper jaw dental and craniofacial development in embryos, hatchlings, and young juveniles, with a comparison to lower jaw development.
The embryonic tooth initiation pattern (illustrated by defining a tooth position formula) does not support the previous models of Odontostichi, Zahnreihen, and Tooth Families, each of which postulates perfect regularity.
Reconsideration of skeletal development of Chelydra serpentina (Reptilia: Testudinata: Chelydridae): evidence for intraspecific variation
Documented intraspecific variation in sequence and timing of formation, chondrification, and ossification of skeletal elements should serve as a caveat for those conducting studies of phylogeny, heterochrony, and evolution with these data.
Ontogeny of the limb skeleton in Alligator mississippiensis: Developmental invariance and change in the evolution of archosaur limbs
An analysis of the early development of the crocodilian limb skeleton and a hypothesis in which the derived skeletal patterns found in crocodilians and birds have originated by a heterochronic process of paedomorphosis is proposed.
Skull development during anuran metamorphosis: I. Early development of the first three bones to form—the exoccipital, the parasphenoid, and the frontoparietal
Early development of the first three bones to form in the Oriental fire‐bellied toad, Bombina orientalis—the parasphenoid, the frontoparietal, and the exoccipital—are described based on examination of serial sections, which may qualify the use of whole‐mount preparations for inferring the sequence and absolute timing of cranial ossification in amphibians.