Weld Synovial joints, characterized by mutual congruent and lubricated joint surfaces Separated by a cavity, they can at the same time offer mobility and tax support and they are a characteristic of vertebrated animals.
An overview of the fossils of the extinct clades of the Gnatostomo suggests that the connections With surfaces that are mutually articulated They came to the fore in the dermal skeleton of the common ancestor of all vertebrates with jaws. The synovial joints in the cartilage tissue were a subsequent innovation of the Gnatostomo.
Joints and evolution
Our species obtained at the time of evolution joints as flexible as resistant? It is an extremely complex question to answer, but the difficulty has not discouraged Neelima Sharma from the University of Chicago, who together with his team They published a study in the magazine this week PLOS Biology What It suggests that, to find the answer, you have to go back to the Older ancestors of the fish With jaws.
Weld connections synovial, that is, we have on shoulders, elbows, knees or hips, are an important feature of the Most vertebrated skeletonsOffering greater mobility and stability compared to other types of joints. This allows bones or cartilage to slide together thanks to a lubricated cavity in between. Although you are connections They are present in both terrestrial vertebrate animals and with bone fishing, it was not clear when they arose in the early evolution of vertebrates.
To answer this question, the Sharma team examined the anatomy and the development of connections In two primitive vertebrates: a kind of fish without a jaw, the Lamprea Jachthavenand two types of cartilage fish, the cat shark and the lob. The analysis revealed the presence of joints in cartilage fishingBut not in the Lampreas. In addition, the first certain proteins and development processes showed the synovial joints of other vertebrates.
A very old joint
The team also made automated tomographs for different shapes and fish fossils to identify one Articulation with similar cavity in the extinct fish Bothriolepisconsidered as the joint Older known synovial. This fish lived in the Devonic, about 360 million years ago.
Together these results show that connections Synovials are present at fish with jaws, but apparently absent in fish without, indicating that these structures They first evolved in the ancestors of the vertebrate animals With jaws. This new work provides crucial information to understand the origin of skeletarchitecture of vertebrates, including people.
«The origin of connections Mobile in our ancestors fishing were moving them and feeding with new forms, “explains Sharma. «This study shows that the development processes are responsible for this connections They appeared in the evolutionary tree of the fish«.
From here, the following studies can focus on analyzing joint morphology in other types of fossil fish and making more comparisons between connections of vertebrate animals with and without a jaw, Unveil more details about early evolution of these structures.