How did tiktaalik provide evidence that amphibians evolved from fish?

Tiktaalik fossils reveal how fish evolved into four-legged land animals. The report shows that the animal had a large, robust pelvic girdle, a prominent hip joint, and long hind fins. The powerful fins could have propelled the beast in the water, but also helped it walk on riverbeds, or scramble around on mudflats

osteogenesis imperfecta (oi) refers to a congenital ailment of bones. in the condition, the bones become brittle or fragile. this ailment is a general result of the defect or mutations in the genes (colia1 or colia2). this mutation results in imperfect collagen formation either in quantity or quality wise.  

there are eight kinds of oi defects, and each kind varies with certain distinctions in symptoms. the usual symptoms include frequent bone fractures, loss of hearing in infants, protruding eyes, discoloration of the white in the eyes, respiratory issues, loosening of the joints, short stature, and other symptoms.