VERTEBRATES According to the molecular clock, a specific method for dating phylogenetic events, vertebrates (Vertebrata) separated from arthropods (Arthropoda) 976±97 Ma (2004HedgesSB_ShoeJL). The latter began to dominate in species diversity with the Cambrian burst of radiation, which occurred 520 Ma (2010EdgecombeGD). This ratio in the fauna of the Earth is still preserved. Approximately 525 Ma, the phylum Chordates separated from the group of bilaterally symmetrical animals (1995ChenJY_ZhouGQ). In turn, the evolution of chordate organisms led to the formation of the first vertebrates at least 500 Ma, from which the jawed mouths 450-400 Ma descended, becoming the ancestors of the placoderms or "armored" fish (Placodermi) (1979 НаумовНП _ КарташевНН ). Sculptural reconstruction of the placoderm Coccosteus from the order Arthrodires, Middle Devonian, 393.3-382.7 Ma ; exposition of the Orlov Paleontological Museum (Moscow); photo by the author. The first cartilaginou...
The ligament of the head of femur, or round ligament, known as ligamentum capitis femoris in Latin, is a crucial element of the hip joint. The journal discusses its role, anatomy, development, pathology, classifications, treatment, diagnosis, synonyms, experiments, history of study, and the application of research results in veterinary science and biomechanics. It also collects and analyzes scientific research, images and intriguing facts about this element. THIS IS THE BIRTHPLACE OF INNOVATION!

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