Related Experiment Video
Updated: Apr 14, 2026
09:15
Processing Embryo, Eggshell, and Fungal Culture for Scanning Electron Microscopy
Published on: August 16, 2019
10.1K
Skeletal remodelling suggests the turtle's shell is not an evolutionary straitjacket.
Gerardo Antonio Cordero1, Kevin Quinteros2
1Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA 50011, USA gcordero@iastate.edu.
Biology Letters
|April 17, 2015
Summary
Turtle shell evolution involves diverse developmental processes. Skeletal remodeling of the shoulder blade (scapula) allows for unique shell shapes, demonstrating developmental plasticity rather than an evolutionary constraint.
Area of Science:
- Evolutionary biology
- Developmental biology
- Comparative anatomy
Background:
- Turtle shell development varies across species, yet the shoulder blade (scapula) is consistently encapsulated within the shell.
- Correlated evolution between shell and scapula development likely drives diverse shell morphologies.
Purpose of the Study:
- To investigate scapula growth and differentiation across 13 turtle species during embryonic, hatchling, and adult stages.
- To understand the role of skeletal remodeling in the evolution of derived turtle shell phenotypes.
Main Methods:
- Phylogenetically comprehensive survey of turtle development.
- Focus on scapula growth, differentiation, and skeletal remodeling.
- Comparative analysis across embryos, hatchlings, and adults of 13 species.
Main Results:
- First description of secondary scapula differentiation via skeletal remodeling in turtles with derived shell phenotypes.
- Box turtles exhibit suprascapula formation through late embryogenesis remodeling, aiding shell closure.
- Soft-shelled turtles show truncated scapula growth linked to similar remodeling, resulting in flattened shells.
Conclusions:
- Skeletal remodeling represents a form of developmental plasticity in turtles.
- This plasticity allows diversification of the turtle body plan, challenging the notion of the shell as an evolutionary constraint.
More Related Videos
Related Concept Videos
01:40Bone Remodeling
41.3K
Bone remodeling is a continuous and balanced process of bone resorption by osteoclasts and bone formation by osteoblasts. In adults, it helps maintain bone mass and calcium homeostasis. While mechanical stress can stimulate turnover as part of the normal maintenance and reparative process, several hormones also regulate bone remodeling.
41.3K
01:09Changes in the Appendicular Skeleton with Age
4.1K
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...
4.1K
01:31Osteoclasts in Bone Remodeling
4.9K
Osteoclasts are cells responsible for bone resorption and remodeling. They originate from hematopoietic progenitor cells present in the bone marrow. Numerous progenitor cells fuse to form multinucleated cells, each with 10-20 nuclei. A single osteoclast has a diameter of 150 to 200 µM. These cells have ruffled borders that break down the underlying bone tissue and release minerals such as calcium into the blood in bone resorption. Osteoclasts cling to bones with their ruffled edges during...
4.9K
01:24Bone Formation by Endochondral Ossification
15.8K
Bone formation, or ossification, begins around the sixth to seventh week of embryonic development. Most bones develop from a cartilaginous template through the process of endochondral ossification. Cartilage formation begins when clusters of mesenchymal cells differentiate into chondrocytes. These chondrocytes proliferate rapidly and secrete an extracellular matrix that becomes encased in a membrane called the perichondrium. The resulting cartilage model provides a template that resembles the...
15.8K
01:31Bone Remodeling and Repair
10.7K
10.7K
01:29Bone Formation by Intramembranous Ossification
17.5K
Intramembranous ossification is one of the two processes involved in the development of bones within an embryo. The flat bones of the face, most of the cranial bones, and the clavicles are formed via this process. During intramembranous ossification, the bones develop directly from sheets of undifferentiated mesenchymal connective tissue.
The process begins when mesenchymal cells in the embryonic skeleton gather together and differentiate into osteogenic cells, which then develop into ...
The process begins when mesenchymal cells in the embryonic skeleton gather together and differentiate into osteogenic cells, which then develop into ...
17.5K