ensuring the continuation of the species.The parents might have brought food
to their young and regurgitated seeds and berries as do modern birds. This
parental care for infants suggests strong social bonds and might explain why
dinosaurs were so successful for so long.
Some dinosaurs might have developed complex mating rituals. Besides
regulating its body temperature, the large sail on dimetrodon’s back might
have been used to attract females. Other dinosaurs might have sported elabo-
rate headgear like present-day birds for much the same purpose. Dinosaurs
might have used complex vocal resonating devices for mating calls. They
appeared to produce sounds by oscillating cartilage in their throats.The larger
the cartilage the lower the sound frequency, enabling some species to make a
noise somewhat like a foghorn, which carried for a long distance. One 75-
million-year-old herbivore had a 4.5-foot-long hollow crest arching backward
from the skull. It was possibly used as a sexual display device or as a resonat-
ing chamber to produce unusual sound effects.Figure 139
Tyrannosaurus rexwas
the greatest land carnivore
that ever lived.
Historical Geology