The sims 3 cc dinosaur
1), making it possible to reconstruct various stages of dental ontogeny in detail. Each tooth position in the battery preserves up to six teeth at successive ontogenetic stages (Fig. We undertook the first ontogenetic study of tooth and tissue interactions in the hadrosaurid dental battery by sectioning large maxillary and dentary batteries and those of embryonic and nestling Hypacrosaurus (Additional file 1: Table S1). Whereas individual teeth appear to have been composed of comparable tissues to those in mammalian teeth the mechanisms that allowed such an unusual dental system to evolve and be maintained have never been investigated and are not understood. This complex chewing surface allowed hadrosaurids to access tough, fibrous plant material by maintaining a constantly replenished oral processing surface with teeth that were at different stages of wear at any given time. Some hadrosaurid jaws have up to 300 teeth stacked in 60 tooth positions with multiple functional teeth at each position forming a large, complex grinding surface. Their success has been linked to the evolution of their complex dental batteries, which consist of multiple generations of small, vertically-stacked teeth that interlock with neighbouring teeth (Fig. Hadrosaurid or “duck-billed” dinosaurs were among the most diverse and abundant terrestrial herbivores of the Late Cretaceous and had evolved spectacular adaptations for more efficient grinding and shearing of plant tissues. The hadrosaurid dental battery thus allows us to follow in great detail the development and extended life history of a particularly complex food processing system, providing novel insights into how tooth development can be altered to produce complex dentitions, the likes of which do not exist in any living vertebrate.
The hadrosaurid dental battery, the most complex in vertebrate evolution, conforms to a surprisingly simple evolutionary model in which ancestral reptilian tissue types were redeployed in a unique manner. We demonstrate that each battery was a highly dynamic, integrated matrix of living replacement and, remarkably, dead grinding teeth connected by a network of ligaments that permitted fine scale flexibility within the battery. The hadrosaurid dental battery is a highly modified form of the typical dinosaurian gomphosis with a unique tooth-to-tooth attachment that permitted constant and perfectly timed tooth eruption along the whole battery. The retention of older generations of teeth was driven by acceleration in the timing and rate of dental tissue formation.
ResultsĬomparisons of hadrosaurid dental ontogeny with that of other amniotes reveals that the ability to halt normal tooth replacement and functionalize the tooth root into the occlusal surface was key to the evolution of dental batteries.
We used these comparisons to pinpoint shifts in the ancestral reptilian pattern of tooth ontogeny that allowed hadrosaurids to form complex dental batteries. We undertook the first comprehensive, tissue-level study of dental ontogeny in hadrosaurids using several intact maxillary and dentary batteries and compared them to sections of other archosaurs and mammals. Despite extensive interest in the adaptive significance of the dental battery, surprisingly little is known about how the battery evolved from the ancestral dinosaurian dentition, or how it functioned in the living organism. Hadrosaurid dinosaurs, dominant Late Cretaceous herbivores, possessed complex dental batteries with up to 300 teeth in each jaw ramus.