The reason for this is that at the places where muscles and tendons attach to the surface of bones, Out door animatronic dinosaur tell-tale surface markings such as elevated ridges of bone or distinctively pitted muscle scars often form. Skeletal bone is a surprisingly plastic material. Bones must change shape as the body grows, or if it has to repair itself following trauma such as a fracture. What may be less obvious is that even when the body is full grown, its bones continue to be remodelled in response to ever-changing patterns of stress and strain. For example, an individual taking up a course of weight-training will deposit extra skeletal bone in order to cope with the increased load, especially if this training regime is continued over time.
In particular areas of the body, where large muscles exert forces on the skeleton, the scarring on bones can be quite distinctive, even in fossils; this creates a crude map that allows some of the original musculature to be reconstructed (Figure 24). Dinosaur costume Such reconstructions are based on the known muscular arrangements seen in related living animals, tempered by allowances for the anatomical differences or novelties seen in the fossil animal that is being investigated.
Although far from scientifically ideal, an example of this kind of approach when trying to understand the musculature of Iguanodon is to use as a starting point information from two of the nearest living relatives of dinosaurs: birds and crocodiles. Animatronic animal Clearly neither of these types of animal represent, at all accurately, the anatomy of Iguanodon: birds are highly modified for flight, have no teeth, have a minuscule tail and unusually modified hips and leg muscles; crocodiles, though more conventionally reptilian in shape, are highly specialized as aquatic predators. Despite these real problems, they provide a general framework or template – termed the ‘extant phylogenetic bracket’, or EPB – for reconstruction that can be supplemented by the finer details of the anatomy of Iguanodon.