Summary of Current Knowledge on Dinosaur Paleobiology
1 February 2000
Recent dinosaur books include:
- Spencer Lucasí Dinosaurs, the Textbook (2nd edition) - this is a good summary, but it is not too in-depth.
- The Complete Dinosaur (Farlow & Brett-Surman)
- Dinosaurs, Spitfires & Seadragons (McGowan)
There are >350 dinosaur genera now - the number of genera has doubled since 1969.
Dinosaurs have an average of 1.2 species per genus.
45% of all genera are known from 1 specimen only.
40 genera are based on teeth alone.
~20% of dinosaurs are known from a ~complete skeleton with skull.
5-7 my is average duration of a dinosaur genus.
It is estimated that 100-200 dinosaur genera were alive at any one time (compared with ~175 genera of large animals living today).
~2100 dinosaur skeletons are known. Because dinosaurs were around for 163 my, that turns out to be 1 skeleton preserved per 67,000 years.
Crested hadrosaurs show strong sexual dimorphism. Non-crested hadrosaurs do not show strong sexual dimorphism. Lots of genera of hadrosaurs were established in the past. Now, non-crested forms of genera are considered juvenilles - they grew crests as they grew larger - one crest form for males and another crest form for females.
Sauropods - some had armoured plating; some have knobbed clubs on the tip of the tail.
A 9-liter capacity egg (such as the moa) is the maximum capacity for any egg, theoretically. There is a fixed limit to the size of eggs.
Dinosaurs grew quickly - they reached adult size in 5 years (for hadrosaurs, at least).
As bones grow, the marrow cavity also grows in size - canít just count growth rings in the bone to get the age of the individual - bonesí internal structures get modified with growth.
75% of the adult dinosaur size was reached in 10 years. Very quick growth in dinosaurs.
Theropods - >100 kinds. Some were tremendously bird-like (ornithomimids, for example, which probably ran like birds, or so the traditional thought says). But, new work notes that their movement had to be different from birds, because birds have no tail and have an almost-horizontal femur. Dinosaurs have a tail and have a ~vertical femur. New ideas say that theropod dinosaurs ran like mammals.
Mosasaurs - some suffered from the bends. Can see tissue damage in vertebrae indicative of the bends.
Ichthyosaurs - ~2 dozen species known. They had the largest eyes in the animal kingdom - some were as big as dinner plates. Only the biggest-eyed ichthyosaurs had the bends - they were going the deepest.
Mammoths and mastodons - the most common large Pleistocene animals found in Ohio - over 200 sites in Ohio have produced them. Mastodons are more common in Ohio. Mammoths are rarer in Ohio.