Who are Placodermi: Placodermi is the first jawed Vertebrate in the history of evolution before all the primitive Vertebrates were jawless. Before Placodermi all the primitive Vertebrate paired appendages was absent but the paired appendages and strong jaw make them powerful predator. Ostracoderms become extinct approximately 450 million years ago when the first time Placodermi … Read more
Placodermi is a very important group of animals for study in the field of evolution of Gnathostomata. The study on the evolution of Placodermi gives us an idea about the evolutionary history of primitive Vertebrates. Placodermi is intermediate between the primitive extinct Ostracoderms and the modern fish, the fossil evidence of Placodermi gives us knowledge … Read more
In class Placodermi, we have placed all the primitive extinct jawed fish and they are divided into different subclass based on the similarities and dissimilarity among them. Different workers tried to classify class Placodermi in different ways but only a few of them get accepted among the science community and we will discuss the most … Read more
Most of the workers believe that Placodermi evolved from the Ostracoderm because Placodermi shows very much similarity with Ostracoderms in various aspects. We can consider Placodermi as an updated version of Ostracodermi with some new advanced features which they gain during the course of evolution. In Ostracoderms, we can see the bony external heavy armour … Read more
Who Are Actually Placodermi: If we talk about the fossil evidence for the primitive Vertebrate we do not have sufficient evidence yet which can give us an exact timeframe when actually Vertebrate arrived on our earth. Now what is the reason behind the missing fossil evidence for the primitive Vertebrate, there are different types of … Read more
