Dinosaur’s fossilized ribcage

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Christine Janis, a fellow graduate student at Harvard in the mid-seventies, was the first to excite my interest in the digestive organs. (real size dinosaur)She pointed out that teeth and jaws tell only half the story. (dinosaur factory)Nearly all plant-eaters have fermenting vats, enlarged chambers where food sits and soaks while microbes attack it with powerful enzymes. Janis stressed how enormous is the variation in location chosen by natural selection for the fermenting site.


Ruminants–the deer–cattle–antelope family–chose a forward site and remodeled their stomach into a complex multi-chambered rumen where the bolus is soaked by enzymes. Since the rumen is located in the forward stomach compartment, a deer, antelope, or buffalo can crop leaves, wad them up into a bolus, pass it down for presoftening, then pass it back up to the teeth for a thorough chew after the leaves have been softened. (life like dinosaur)Forward locations offer substantial advantages—teeth are saved from unnecessary wear when all food is presoaked and softened. Horses, rhinos, and elephants, on the other hand, chose a rearward location, a pocket evolved far back in the intestine or colon. Rearward location has one major disadvantage—the bolus can’t make any sort of return to the mouth. But since the rear of the body cavity is spacious, its advantage is that rearward fermenting vats can be huge.


A dinosaur’s fossilized ribcage can reveal a great deal about the organs it housed—information largely ignored until recently. For one thing, how big the dinosaur’s digestive chambers were can be gauged by the size of the ribcage.(animatronic dinosaur costume) Orthodoxy maintains that many dinosaurs were too weak-toothed to eat tough plants; but large digestive tracts could compensate for weak teeth. Janis made a point often ignored by bone-and-teeth paleontologists: The better the enzyme soak given to food, the fewer the teeth needed to deal with any specific food texture. A good case in point: Today’s herbivorous lizards usually have relatively small, weak teeth and until recently had the reputation of being inefficient plant-eaters, but recent experiments show that some lizards carry out very effective rearward fermentation in their extra-long intestines. Giant ground birds—rheas and ostriches—have tiny heads and no teeth whatever, yet these birds successfully employ rearward fermentation on a large scale.