Read the previous section: Spiral cleavage, an oblique matter. Annelids, arthropods and vertebrates show a remarkable morphological diversity (Chipman, 2010). Beneath this multiplicity of shapes and forms lies a common pattern of body organization—a trunk divided into repeated parts. This pattern and the developmental process that generates it are known as segmentation (Minelli and Fusco, […]
Tag: evolution
Read the previous section: What a larva is. Francis M. Balfour set the pace on discussions about the evolutionary importance of larvae by addressing many of the fundamental questions regarding larval evolution (Balfour, 1874; Balfour, 1880; Balfour, 1881). He wondered about the ancestry of larvae. Can larvae reveal the ancestral forms of metazoans? He indicated […]
The evolution of segmentation is a controversial topic in biology. Biologists have struggled to answer even the most basic questions. Were our ancestors segmented or not? Has segmentation evolved only once, or has it evolved multiple times independently? What is a segment, after all? The basis of such confusion is partly biological. Biology is complicated, […]
I wrote a text about the development and evolution of the turtle shell on The Node: Turtles in a nutshell. It shows the beginning of shell formation in embryos and how this can help us understand the evolution of such unique body pattern. 3D animations and fossils are included! Never thought I would post a […]