TY - JOUR

T1 - Morphogenetic and constructional differences of the carapace of aquatic and terrestrial turtles and their evolutionary significance

AU - Cherepanov, Gennady

N1 - Publisher Copyright: © 2019 Wiley Periodicals, Inc.

PY - 2019/10/1

Y1 - 2019/10/1

N2 - The postembryonic development of the turtle carapace was studied in the aquatic Еmys orbicularis and the terrestrial Тestudo graeca. Differences in the structure of the bony shell in aquatic and terrestrial turtles were shown to be associated with varying degrees of development of epidermal derivatives, namely, the thickness of the scutes and the depth of horny furrows. Sinking of the horny furrows into the dermis causes local changes in the structure of the collagen matrix, which might precondition the acceleration of the ossification. Aquatic turtles possess a relatively thin horny cover, whose derivatives are either weakly developed or altogether absent and thus make no noticeable impact on the growth dynamics of bony plates. Carapace plates of these turtles outgrow more or less evenly around the periphery, which results in uniform costals, relatively narrow and partly reduced neurals, and broad peripherals extending beyond the marginal scutes. In terrestrial turtles (Testudinidae), horny structures are much more developed and exert a considerable impact on the growth of bony elements. As a result, bony plates outgrow unevenly in the dermis, expanding fast in the zones under the horny furrows and slowly outside these zones. This determines the basic features of the testudinid carapace: alternately cuneate shape of costals, an alternation of broad octagonal and narrow tetragonal neurals, and the limitation of the growth of peripherals by pleuro‐marginal furrows. The evolutionary significance of morphogenetic and constructional differences in the turtle carapace, and the association of these differences with the turtle habitats are discussed.

AB - The postembryonic development of the turtle carapace was studied in the aquatic Еmys orbicularis and the terrestrial Тestudo graeca. Differences in the structure of the bony shell in aquatic and terrestrial turtles were shown to be associated with varying degrees of development of epidermal derivatives, namely, the thickness of the scutes and the depth of horny furrows. Sinking of the horny furrows into the dermis causes local changes in the structure of the collagen matrix, which might precondition the acceleration of the ossification. Aquatic turtles possess a relatively thin horny cover, whose derivatives are either weakly developed or altogether absent and thus make no noticeable impact on the growth dynamics of bony plates. Carapace plates of these turtles outgrow more or less evenly around the periphery, which results in uniform costals, relatively narrow and partly reduced neurals, and broad peripherals extending beyond the marginal scutes. In terrestrial turtles (Testudinidae), horny structures are much more developed and exert a considerable impact on the growth of bony elements. As a result, bony plates outgrow unevenly in the dermis, expanding fast in the zones under the horny furrows and slowly outside these zones. This determines the basic features of the testudinid carapace: alternately cuneate shape of costals, an alternation of broad octagonal and narrow tetragonal neurals, and the limitation of the growth of peripherals by pleuro‐marginal furrows. The evolutionary significance of morphogenetic and constructional differences in the turtle carapace, and the association of these differences with the turtle habitats are discussed.

KW - development

KW - morphogenetic mechanisms

KW - turtle shell

KW - variation

KW - CHELONIA

KW - ABNORMALITIES

KW - REPTILIA

KW - TORTOISE

KW - OSTEOLOGY

KW - PATTERNS

KW - SHELL SHAPE

KW - TESTUDINES

KW - HETEROCHRONY

KW - SKELETAL DEVELOPMENT

UR - https://onlinelibrary.wiley.com/doi/abs/10.1002/jmor.21050

UR - http://www.scopus.com/inward/record.url?scp=85070751043&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/morphogenetic-constructional-differences-carapace-aquatic-terrestrial-turtles-evolutionary-significa

U2 - 10.1002/jmor.21050

DO - 10.1002/jmor.21050

M3 - Article

VL - 280

SP - 1571

EP - 1581

JO - Journal of Morphology

JF - Journal of Morphology

SN - 0362-2525

IS - 10

ER -