Hyperossification in miniaturized toadlets of the genus Brachycephalus (Amphibia: Anura: Brachycephalidae): Microscopic structure and macroscopic patterns of variation

• Published in: Journal of morphology (1931) Vol. 270; no. 11; pp. 1285 - 1295
• Main Authors: Clemente-Carvalho, Rute B.G., Antoniazzi, Marta M., Jared, Carlos, Haddad, Célio F.B., Alves, Ana C.R., Rocha, Henrique S., Pereira, Gabriela R., Oliveira, Davi F., Lopes, Ricardo T., dos Reis, Sergio F.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-11-2009
• Subjects: Animals; anura; Anura - anatomy & histology; Anura - physiology; Female; Humans; Male; miniaturization; Osteogenesis - physiology; Sharpey fibers; skeletal morphology; Skull - physiology; Skull - ultrastructure; skull morphology; Species Specificity; Spine - physiology; Spine - ultrastructure; Synchrotrons
• ISSN: 0362-2525; 1097-4687
• DOI: 10.1002/jmor.10755

Species of the genus Brachycephalus, have a snout‐vent length of less than 18 mm and are believed to have evolved through miniaturization. Brachycephalus
ephippium, is particularly interesting; because its entire skull is hyperossified, and the presacral vertebrae and transverse processes are covered by a dorsal shield. We demonstrate in this paper that, at the macroscopic level, a completely hyperossified skull and dorsal shield occur only in B. ephippium, but not in B. ferruginus, B. izechsohni, B. pernix, B. pombali, B. brunneus, B. didactylus, and B. hermogenesi. An intermediate condition, in which the skull is hyperossified but a dorsal shield is absent, occurs in B. vertebralis, B. nodoterga, B. pitanga, and B. alipioi. The microscopic structure of hyperossification was examined in skulls of B. ephippium and B. pitanga, revealing a complex organization involving the presence of Sharpey fibers, which in humans are characteristic of periodontal connections. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.