Posted on 03/13/2008 4:54:07 AM PDT by Renfield
Pterosaurs, like their dinosaur relatives, didn't wait until they were fully grown to have sex, a new study suggests.
Researchers examined microscopic tree ring-like growth markings in hundreds of bones from a species of the extinct flying reptiles discovered in central Argentina in the 1990s.
The Pterodaustro guiñazui bones came from multiple individuals, including an embryo inside an egg and adults with wingspans between 1 to 8 feet (0.3 to 2.5 meters).
P. guiñazui lived during the mid-Cretaceous, about a hundred million years ago.
"It is quite amazing that even after millions of years, the microscopic structure of the bone is still intact," study author Anusuya Chinsamy-Turan, a paleobiologist at the University of Cape Town in South Africa, said by email.
Rapid Growth
The team found that the pterosaur attained about 53 percent of its adult body size in just two years.
At that point, the flying reptile was likely sexually mature. Its growth continued slowly for three or four more years.
(Related news: "Dinosaurs Had Sex As Teens, Study Says" [July 20, 2007].)
"Then they stopped growing and maybe they didn't live much longer," said paleontologist and study co-author Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum in Los Angeles, California.
The finding shows that the flying reptiles, like dinosaurs, did not grow throughout their entire lives—as do modern turtles and crocodiles, Chiappe said.
Chiappe, Chinsamy-Turan, and Laura Cordornú from the National University of San Luis in Argentina described the growth patterns of the pterosaur last month in the journal Biology Letters.
(The research was funded in part by a grant from the National Geographic Society. National Geographic News is owned by the National Geographic Society.)
Kristi Curry-Rogers, a paleontologist at Macalester College in St. Paul, Minnesota, studies growth patterns in dinosaurs.
She said the pterosaur growth pattern is similar to what she and other scientists have found in a variety of dinosaurs.
"All of them grow faster than modern reptiles, and none of them grow as fast as modern birds," she said. "That's something that's consistent across analyses."
Modern birds reach their full adult size within about a year but often delay reproduction for several years. Eagles, for example, begin to mate at about age four.
The addition of pterosaurs to this data set pushes the evolution of faster growth rates back along the lineage of animals that split from modern reptiles and gave rise to birds, Curry-Rogers noted.
"We're seeing some really interesting biological changes that I can't imagine didn't contribute to their long success on Earth," she added.
Grow Fast, Die Young?
Their faster growth rates were beneficial because they likely allowed early sexual maturity, Chiappe said.
Other scientists have speculated that such a growth strategy helped dinosaurs pass on their genes before the harsh, and often deadly, realities of older age set in.
(Related: "For Tyrannosaurs, Teen Years Were Murder" [July 13, 2006].)
Since the tree ring-like growth marks end once a pterosaur has reached adult size, Chiappe said he and colleagues are uncertain how long P. guiñazui lived.
However, he noted that only a few individuals in their sample of hundreds of pterosaurs appeared to be more than six or seven years old.
"It's likely that these animals did not live very long," he said.
They didn’t have porch lights, either. And no Zippos to light the flare a few times...
twisttheknifeping
Hmm... So, did the pterosaurs merely mate early and retain the sperm for reproduction later in their adult life, or did they lay their eggs and do the whole shebang before full adulthood?
The reason is that either scenario presents different problems from an evolutionary standpoint. They should probably answer these questions before posing wacky theories like this.
Paedosaurus?
Pterosaurs had sex as youths? God, I hope so. The idea of OLD pterosaurs having a flying F-— brings to mind a horrible image.
(Note: will someone post the obligatory photoshopped image of Helen Thomas as a pterosaur?)
Well, my dog had to be neutered by 6 months, due to being sexually mature by then, but was not fully grown until age 4 (mastiff). The females are supposed to be 2 yo before they are bred, because they need to be more mature in order to breed safely.
Chickens lay eggs at 6 months, but I doubt they can be fertile, they’re just little pullet eggs.
You’re right... It’s not clear at all (at least from this article) how they came to these conclusions about their sexual habits. I’m guessing (hoping?) there was more evidence that the reporter didn’t bother including either because they were lazy, or didn’t realize that it was an essential part of the explanation! LOL
The other thing that’s interesting is that if these animals had a life-span of only about 10 years, that would kind of “knock out” the theory that they were still “youths” at the time of sexual maturity. Compared to humans, yeah of course, but for animals? Ridiculous...
The day they can be so precise about the sex habits of an animal millions of years ago, they will know your sex habits of the past 24 hours, in your bedroom. These conjectures lead me to deeper UNBELIEF in the sanity of modern Darwinian science.
The problem with this wacky theory is it de-emphasizes full adulthood for the species, and survivability to old age is no longer an evolutionary plus. Essentially, this type of reproductive model would result in inevitable alteration of the species over a short period of time due to reproductive pressures, with an emphasis on mutations that expand or enhance the reproductive advantages of its youth. Features prominent in full grown adults such as size would become vestigial.
The only explanation for such over specialization that I can see is that the species had a complex social system where the full grown adults enhanced the reproductive advantages of the younger individuals by caring for, protecting, and feeding their offspring’s offspring and/or genetic descendants. But the gist is that the reproductive period would naturally increase over time as those who remain capable of passing on their genes the longest are more likely to have more offspring. Such changes in physiology over time would have other effects on the species later development.
I guess what I’m saying is that such a reproductive model is inherently unstable and any species which has such a model would either become extinct due to overspecialization or will become a candidate for inevitable and rapid evolutionary change... resulting in extinction for the originals.
Your comment makes sense to me. Thanks.
That photo is fake, right???
LOL!
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