Natural Science Forum / Biology / Paleontology / August 2008

http://news.yahoo.com/s/livescience/20080806/sc_livescience/planteatingdinos
grewfasttofendofftyrannosaurs;_ylt=Ag8E_9QMlfjLhI5FuZYoMogPLBIF

In my own personal estimation (IMOPE), a better title for the linked article
would be something along these lines: "At Least One Species Of Hadrosaur
Grew Faster Than Tyrannosaurs To Limit Predation." Note that the exact title
given the internet piece--"Plant-Eating Dinos Grew Fast To Fend Off
Tyrannosaurs"-- is once again not quite semantically correct; investigators
analyzed only one species of hadrosaur. By using the word "Dinos," the
author conveys the unsubstantiated conclusion (in this article, at least)
that more than one kind of herbivorous dinosaur demonstrated astonishingly
rapid growth.

Still, both that Internet headline and my own retitled Subject Line are in
actual fact rather misleading. Here's why. Near the conclusion of the piece,
the investigators admit that yet another special adaptive factor could help
explain why that one specific type of hadrosaur might have experienced
growth rates roughly three to five times faster than their carnivorous
tyrannosaur counterparts: namely, that Hypacrosaurs stebingeri--the analyzed
hadrosaur demonstrating fast growth--reached sexual maturity at "only two or
three years of age," while T. rex required by implication many additional
years to attain reproductive capabilities (the investigators claim that T.
rex reached adult size in 20 to 30 years--theorectically, of course, the big
bad critter could have been able to reproduce at a younger age); so, if an
animal can reproduce with super rapidity at a younger age, that creature
should be able to withstand the ravages of efficient predatory attacks,
maintaining viable populations.

Also, just to throw in another controversy, the investigators appear to
so-stipulate that T. rex was an active predator, neglecting the undeniable
fact that the famous late Cretaceous carnivore has never been fully,
universally, exonerated as an obligate scavenger. The debate rages on, of
course. My own opinion is that T. rex, like its large modernday carnivorous
counterparts, likely seldom if ever refused an opportunity to
scavenge--though it could have also attacked, when necessary, with forceful
and efficient killing finality.

Trilobites In The Marble Mountains, Mojave Desert, California (the specific
place that first inspired my life-long interest in paleontology):
http://members.aol.com/Waucoba7/latham/latham.html

Here are the critical first few paragraphs of the linked Internet article:

"What some dinosaurs lacked in body armor, they made up for in size. The
duck-billed hadrosaur grew to adulthood much faster than its predators, such
as tyrannosaurs, a new study suggests.

"By about age 10, the plant-eating hadrosaur called Hypacrosaurus stebingeri
had likely ballooned to its mature length of 30 feet (9 meters) from nose to
tail tip, the study showed. Meanwhile, the meat-eater and hadrosaur-enemy
Tyrannosaurus rex would have still been a relative pipsqueak at that age,
not reaching adult size until 20 to 30 years of age.

"The size difference, the researchers say, would have forced the carnivorous
dinos to hunt juveniles of H. stebingeri.

"The carnivorous dinosaurs are looking at the younger herbivorous
dinosaurs," Lisa Noelle Cooper, a doctoral student at Kent State University
in Ohio, told LiveScience. "They are actually hunting the younger ones. Once
the Hypacrosaurus reaches that adult size, we think it's safer from
predation. It's a size refuge." Cooper is also a researcher with the
Northeastern Ohio Universities College of Medicine.

"Once T. rex reached adult size, about 40 feet (12 meters) in length, the
tables would of course turn, with the meat-eater coming out on top."