CONNECTING LINKS AND ITS EVOLUTIONARY SIGNIFICANCE

1. CONNECTING LINKS AND ITS EVOLUTIONARY SIGNIFICANCE By DR.D.S. Rathod DEPT. OF ZOOLOGY 01

2. CONNECTING LINKS Fossil Connecting Links: Fossil animals exhibitig characters of two adjacent taxonomic groups are called fossil connecting links. There are various type of fossil connecting links Ichthyostegia ,Seymouria ,Archeopteryx 1.Ichthyostegia It is a connecting link between fishes and amphibian. It possess both pisces and amphibian charecters. 3

3. Fossil Connecting links Piscean charecters Autostylic jaws,Internal nares,lateral line system, Fin rays in caudal fin. Amphibian charecters Well developed limbs and girdles (Pectoral , pelvic) 4

4. Fossil connecting link: Archeopteryx : It is fossil form It is a connecting link between reptiles and birds. It was a bird like animal. It possess cherecters of reptiles and aves charecters. Reptile charecters: Lizard like ,Jaw with homodent teeth ,solid bones ,incoplete division ofheart. Aves Charecters : Presence of beak, Wings ,feathers and small cranium

6. Living connecting link: Living animal exhibit charecter of two group is called living connecting link Duck Bill Playtipus: It is living connecting link It is a connecting link between reptiles and Mammals. It possess charecters of reptiles and Mammals. Mammal charecters: They are definatly mammals because have mammalian charecters , Mammary gland ,hair, Diaphragam ,single aortic arches

7. Duck Bill Platypus

8. Living connecting link: Perpatus: It is a connecting link between annelida and Arthropoda. Annelida charecters: Body is segmented and worm like Arthropods charecters: Jointed legs with claw and trachea is respiratory organ

9. Living connecting link: Balanoglossus: It is a connecting link between invertebrates and vertebrates. Dipnoi is living connecting link between in fishes and amphibians. Evolutionary Significance It help to understand evolution in the major group of animals It support the statement of Herbert spencer and Darwin

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