http://en.wikipedia.org/wiki/Notochord
Notochords were the first "backbones" serving as support structures in chordates such as Haikouichthys.Notochords were advantageous to primitive fish-ancestors because they were a rigid structure for muscle attachment, yet flexible enough to allow more movement than, for example, the exoskeleton of the dominant animals of that time.Embryos of vertebrates have notochords today, as it retained a key role in signalling and coordinating development even as it was lost in most adults. In most tetrapods, they eventually develop into the nucleus pulposus of the intervertebral discs.
Notochords were the first "backbones" serving as support structures in chordates such as Haikouichthys.Notochords were advantageous to primitive fish-ancestors because they were a rigid structure for muscle attachment, yet flexible enough to allow more movement than, for example, the exoskeleton of the dominant animals of that time.Embryos of vertebrates have notochords today, as it retained a key role in signalling and coordinating development even as it was lost in most adults. In most tetrapods, they eventually develop into the nucleus pulposus of the intervertebral discs.
No comments:
Post a Comment