Ancestry of Reptiles 3. Living craniates share a set of derived characters that distinguishes them from other chordates. Nothing is known about the origin of primitive Prototheria, for fossils older than Pleistocene are unknown. Chordate ancestors were soft bodied animals. Loading... PPT – Echinoderms and Invertebrate Chordates PowerPoint presentation | free to view - id: 253502-ZDc1Z. Excretory System 15. ADVERTISEMENTS: In this article we will discuss about Reptiles:- 1. ADVERTISEMENTS: In this article we will discuss about Reptiles:- 1. Excretory System 15. THE ORIGIN OF CHORDATA. It proposes that the origin of chordates, which took place about 570 million … This is the Garstang’s theory. Of all the theories regarding the ancestry of chordates from some non-chordates, Garstang’s suggestion that the chordates have evolved from some free-swimming echinoderm larvae (possibly auricularian larvae) by means of paedomorphosis has been accepted by … Hank introduces us to ourselves by taking us on a journey through the fascinatingly diverse phyla known as chordata. Introduction. Adaptive Radiation 6. Circulatory System 13. Habit and Habitat 7. Habit and Habitat 7. View and Download PowerPoint Presentations on VERTEBRATE JAW ORIGIN PPT. Living craniates have a set of derived characters. Skin 9. Such similarity can be only due to common ancestry, and phylogenetic relationship of hemichordates and chordates cannot be denied. Size 8. Get the plugin now. Nervous System and Sense Organs 14. ... it may be suggested that Balanoglossus and other chordates … 1. Circulatory System 13. and the Cephalochordata (amphioxus). The origin of a head—with a brain at the anterior end of the dorsal nerve cord, eyes and other sensory organs, and a skull—opened up a new way of feeding for chordates: active predation. Respiratory System 12. During Jurassic period, there were atleast 5 well … … 1. The Phylum Chordata includes the well-known vertebrates (fishes, amphibians, reptiles, birds, mammals). Origin of Reptiles 2. Chordates derive their name from one of their synapomorphies, or derived features indicating their common ancestry.This is the notochord, a semi-flexible rod running along the length of the animal.In those chordates … Origin of chordates Chordates evolved sometime during Cambrian period, 500 million years ago during Cambrian explosion, almost at the same time when invertebrates were beginning to evolve. You can change your ad preferences anytime. Digestive System 11. Skin 9. Actions. Characters common to chordates and higher non-chordates: There are a number of features in which the chordates resemble the higher nonchordates or invertebrates. History 4. It is believed that Chordates have originated from invertebrates. There are various the­ories regarding the origin of the chordates from the non-chordate groups. Digestive System 11. The evolution of the Metazoa from unicellular/colonial organisms occurred some 1,300–600 Myr ago in the pre-Ediacaran period (Conway Morris, 1998). Bateson (1887) included Hemichordata in phylum Chordata, since then a close relationship has been acknowledged between hemichordates and chordates. Skeleton System 10. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. Evolutionary Gain 5. Size 8. The Adobe Flash plugin is needed to view this content . Most of the theories suffer from serious defects. Arthropods, annelids and chordates all possess segments. Hence they were not preserved as Fossils. It is difficult to determine from which invertebrate group the chordates were developed. Origin of Reptiles 2. They have remained primitive probably due to isolation from rest of World in Australia and New Zealand. It remains unclear, however, whether the segments of these animals evolved independently or instead were derived from a common ancestor. All chordates share four basic features. Many biology theories were put forward to explain the Origin of Chordates. Hemichordates and Chordates perhaps evolved from a common ancestor, possibly like present-day echinoderm (Garstang’s Hypothesis) or hemichordate larvae via .