What is Origin of bones and teeth in vertebrates?

Origin of bones

Introduction:

Scientists study all the fossil remains of ancient fish, and scientists have revealed a turning point in the formation and development of one of the most important parts of humans and all the other animals which are bone. While bones basically provide a  frame structure to support and shape the body, bones are the hard tissues that are always changing and also provide other benefits to the bodies of vertebrates. The specific features of bones are that they maintain themselves, repair injuries, and provide essential nutrients to the bloodstream.

Evolution:

Possession of bones is a typical feature of vertebrates, and bones started originating from the process of mineralization almost close to the basal membrane of the skin, giving elevation to tooth-like structures and also their protective shields in animals to protect them from demineralization by the formation of a soft ad delicate cartilage-like endoskeleton. Research and a combination of different types of fossils anatomy and all the genetic information from modern species have helped us a lot and improved our knowledge of the evolution of bone in organisms. 

The development o vertebrates were followed by jawless animals with an endoskeleton formed from cartilage, like hag-fishes or lampreys.

The other next step was the appearance of mineralized skeletal parts in organisms which gave a major evolutionary jump directly to the formation of the vertebrate lineage.

The primitive bones, however, were totally different from human skeletons today. In the prehistoric era, bone was better like hard concrete that grew on the exterior body of fish to give a protective shell and save them from damage. But according to a new research study, the first bones with living cells like same found in humans evolved almost 400 million years ago and they were like skeletal batteries They provided prehistoric fish with minerals required to travel long distances and journeys. These fossilized appendages in the research are known as “Osteo-stracans”

The cells that become the hard, mineral part of bone as a part of skeletal growth are called osteocytes, The primitive animals with bone didn’t have osteocytes, but also some modern fish also don’t possess these cells, leading all the paleontologists to wonder when and why these bone cells first formed.

Vertebrates have two different sets of skeletons, an exoskeleton which forms the dermal skull roofs, scales, teeth, fin rays, and other structures like these. and an endoskeleton forms the neuro-cranium, vertebra in the backbone, appendicular skeleton, and other appendages like these. The endoskeleton consists of endochondral bones that are performed of cartilage and later on replaced by hard and mineralized bones, the main components of the exoskeleton are the dermal bones which develop in the dermis by the process of membranous ossification.

 A mineralized skeleton is considered to have appeared initially as exoskeleton elements.  All the bony fish possess the exoskeleton in the form of fin rays and dermal scales.