Presumably the typical dermal bones found in fishes (including placoderms) became secondarily sunken exoskeletal elements concomitant with the shift in developmental interactions to induce membranous ossification in a deeper layer of the dermis, as found in amniotes. While their stingers look pretty intimidating, they rely more on their massive claws to kill prey. Limits on Animal Size and Shape - Biology LibreTexts Roth VL: The biological basis of homology. Animals that live or partially live outside of the water need some type of skeleton in order to move and support themselves. Oxford: Oxford University Press; 1971. von Baer KE: Entwicklungsgeschichte der Thiere: Beobachtung und Reflexion. Sire JY, Donoghue PCJ, Vickaryous MK: Origin and evolution of the integumentary skeleton in non-tetrapod vertebrates. This discovery was made in 2014 by a team from Canadas Simon Fraser University. CAS Bombina orientalis (C) Enlarged image of the primordial gastralia, showing the matrix that is stained with Alcian blue (arrowhead), which appears transiently before the bony tissue is formed. PubMed J Morphol 1939, 65:383406. Flying fish are just one impressive example of a species with an endoskeleton, an internal skeleton typically made of bone and found in vertebrates, including mammals, birds, reptiles, amphibians, and fish. J Anat 2007, 211:737753. (B) Endoskeleton with perichondral ossification. In resulting chimeras, these grafted cells gave rise to a skeletal element, which in birds is normally derived from the mesoderm. Wang Z, Pascual-Anaya J, Zadissa A, Li WQ, Niimura Y, Huang ZY, Li CY, White S, Xiong ZQ, Fang DM, Wang B, Ming Y, Chen Y, Zheng Y, Kuraku S, Pignatelli M, Herrero J, Beal K, Nozawa M, Li QY, Wang J, Zhang HY, Yu LL, Shigenobu S, Wang JY, Liu JN, Flicek P, Searle S, Wang J, Kuratani S et al: The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan. J Morphol 2009, 270:13641380. Does eating close to bedtime make you gain weight? Hyoid crest cells are distributed extensively in the sphenethmoidal region of the cranium. However, studies of comparative morphology provide no evidence of interchangeability between endo- and exoskeletons [7]; the two historical lines of endo- and exoskeletal systems are likely to have evolved quite independently from each other. : Phylogeny and function. Noden (1982, 1984) [80,81] placed the neural crest-mesodermal boudary in the dermal skull roof in the rostral part of the avian frontal (A), whereas Couly at al. This theory was refuted as being based on inaccurate concepts of histogenesis, including the concept that skeletogenic differentiation can take place equally in mesodermal and ectodermal (neural crest) cell lineages. Xenopus laevis Skeletal systems of vertebrates are intolerant of such incongruities (reviewed by [6]). The exoskeleton is made up of hard bones and malleable cartilage. Crompton AW, Parker P: Evolution of mammalian masticatory apparatus. Hanken J, Gross JB: Evolution of cranial development and the role of neural crest: insights from amphibians. It is true that the morphological homology of skeletal elements cannot be reduced directly to the developmental program, or homology of genes, involved in the generation of homologous structures.
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