Skin of Scoliodon (Integument)

Skin of Scoliodon

The skin of Scoliodon:  The leathery skin or integument of Scoliodon have both dermis and epidermis layers, the outer layer of integument in Scoliodon is the epidermis and the skin layer below the epidermis is known as dermis or corium layer. The tissues of the epidermis are ectodermal in origin while the tissues in the … Read more

Body Aperture of Scoliodon  

Scoliodon Habits Habitat and Geographical Distribution

Scoliodon is a marine cartilaginous fish, Scoliodon also known as Dogfish, they are an active predator, we will discuss the aperture or pores present on their body. Scoliodon have a streamlined body shape, they have a blackish appearance on the dorsal side and white coloration on the ventral side, the body surface is rough due … Read more

Scoliodon: Habits Habitat and Geographical Distribution  

Scoliodon Habits Habitat and Geographical Distribution.

Scoliodon: A Cartilaginous Fish:  Scoliodon is a cartilaginous fish, they are aquatic, the body is streamlined, the body is covered by scales(dermal denticles), they are all marine. Scoliodon is a true fish, all the fishes can be classified into two categories based on their endoskeleton, cartilaginous fish and bony fish.  All the cartilaginous fish are … Read more

Placodermi: Characteristics Classification Biological Significance 

Biological Significance of Placodermi

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

Biological Significance of Placodermi 

Biological Significance of Placodermi

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

Classification of Placodermi  

Placodermi and Their Timeline Fossil Evidence

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

Characteristics Features of Placodermi 

Climatius or Spiny Shark

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

Placodermi and Their Timeline 

Placodermi and Their Timeline

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