Psittacosaurus adult found with 34 juveniles

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

In case this news item has not been mentioned yet, the new 
issue of Nature has a story about a new Psittacosaurus 
find from Liaoning.

Meng Q., Liu J., Varricchio D. J., Huang T. & Gao C. 
Nature, 431. 145 - 146 (2004).
See also:
http://www.newscientist.com/news/news.jsp?id=ns99996377

http://www.nature.com/news/2004/040906/full/040906-9.html
Meng Q., Liu J., Varricchio D. J., Huang T. & Gao C. 
Nature, 431. 145 - 146 (2004).

Fossil hints at devoted parenting in dinosaurs 
Prehistoric familial care may explain instincts of modern 
birds and crocodiles. 
Fossil hunters in China have unearthed what looks like the 
final resting place of an adult dinosaur with 34 
offspring. The unique discovery shows that at least some 
dinosaurs cared for their young after they hatched out, 
and suggests that the parental instincts of present-day 
birds and reptiles such as crocodiles may have a common 
evolutionary precursor.

In the fossilized group of horned dinosaurs called 
Psittacosaurus, a fully grown individual is surrounded by 
34 youngsters, all huddled within an area of 0.5 square 
metres. It is almost certainly a family group rather than 
a happenstance collection of dead dinosaurs, says David 
Varricchio of Montana State University in Bozeman, part of 
the team who unearthed the bones in Liaoning, China. 

"It does have that 'wow' aspect to it," he told 
news@nature.com. "It's more likely than not a family. It's 
hard to imagine [unrelated] whole skeletons being 
transported to the same place all together."

Simply the nest?

Although some groups of dinosaurs, such as theropods and 
hadrosaurs, are thought to have made nests, the find seems 
to be the first clear example of dinosaur parenting. It is 
not clear whether the 75-centimetre-long adult is a male 
or a female, Varricchio says. But the doting parent's sex 
was not necessarily of any consequence when it came to 
looking after the kids. Varricchio points out that in many 
living bird species, both parents help out in the nest.

It is also uncertain what parental care might have 
involved for these dinosaurs. Perhaps the parent simply 
kept the young close to keep an eye on them, Varricchio 
suggests, as chickens do today. "In many birds, the young 
stay with the parent; the adult leads them to food and the 
young generally mill about behind them," he says.

"It is an amazing snapshot, a really nice, serendipitous 
finding," says Paul Barrett, a dinosaur expert at the 
Natural History Museum in London. But he cautions that the 
evidence for family life remains circumstantial at this 
stage.

Nevertheless, the arrangement is "very suggestive of post-
hatching parental care", Barrett admits. The youngsters 
are all around 20-centimetres long, suggesting that they 
represent a single brood.

Cause of death

The fossils' lifelike crouching poses also raise the 
question of what killed and preserved them. Although a 
volcanic eruption might seem the obvious culprit, 
Varricchio says that it is hard to imagine volcanic ash 
burying the dinosaurs quickly enough to preserve them like 
this.

It is more probable, he suggests, that they were entombed 
when an underground burrow collapsed, or drowned by rising 
flood waters. Many of the dinosaurs have their heads 
raised, which might indicate such an event. Barrett adds 
that the bowl-like depression in which the fossils were 
found is reminiscent of a nest, although he adds that this 
is very speculative.

The question of whether the dinosaurs lived (and perished) 
in burrows is one that Varricchio hopes to answer soon, 
ideally with the aid of further fossil finds. Such 
discoveries could give further insight into prehistoric 
family life, he adds. Earlier findings have hinted at the 
possibility that psittacosaurs might have lived in groups 
containing three or four adults, meaning the single-parent 
family may not have been the norm.