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Fossil 'Suggests Plesiosaurs Did Not Lay Eggs'
thebchuckster writes "Scientists say they have found the first evidence that giant sea reptiles — which lived at the same time as dinosaurs — gave birth to live young rather than laying eggs. They say a 78 million-year-old fossil of a pregnant plesiosaur suggests they gave birth to single, large young."
More science, please.
The Kruger Dunning explains most post on
Shouldn't be too surprising- livebearing shows up in all sorts of families that typically lay eggs- especially aquatic animals. Everyone is familiar with the humble guppy. You buy one for your daughter despite your better judgement- one week later you're overrun with the gaudy ugly fish as the live young start popping out everywhere. Many species of snail give birth to live young. Or "nearly so". Malaysian Trumpet snails and Quilted Melania two "cloning" species can pop out up to 9 live babies at a time. Even sexually reproducing snails can give live birth- species of Tylomelania from Sulawesi lay a single egg at a time that disolves before your eyes (if you're lucky) to reveal a minature snail. That doesn't mean live-bearing fish or mollusks are common- and if this dino gave live-birth, it doesn't mean that it was common with dinosaurs either.
"That's the way to do it" - Punch
Very interesting. I suppose it makes logical sense that sea living creature would find it difficult to safeguard eggs, and with its size these would be very noticeable (and nutritious!). I guess it is similar to whale sharks nowadays, which are ovoviviparous in their reproduction (wikipedia link as below): the "embryos develop inside eggs that are retained within the mother's body until they are ready to hatch. Ovoviviparous animals are similar to viviparous species in that there is internal fertilization and the young are born live, but differ in that there is no placental connection and the unborn young are nourished by egg yolk; the mother's body does provide gas exchange (respiration), but that is largely necessary for oviparous animals as well."
http://en.wikipedia.org/wiki/Whale_shark
http://en.wikipedia.org/wiki/Ovoviviparity
However, the comment about single young is even more interesting - as whale sharks are even bearing very many (live) young. Maybe different again? (no expert here, just curious!)
It's not good science unless it upsets somebody who dislikes having their gospel (or canon, for the more sociologically correct) challenged. Good science always bruises egos.
I don't personally get it, though. Do the authors of buggy code that gets patched by others also get upset? They should be happy the code finally works.
Still, why on earth would it ever upset someone who didn't discover/propose/create what's being challenged?
You're correct with regards to sharks, but so far all evidence suggests dinosaurs laid eggs (including modern ones as birds). The creature being discussed in this article is a large marine reptile from the time of the dinosaurs, but it isn't a dinosaur. There are many extinct and large reptilians besides dinosaurs, including plesiosaurs, mosasaurs, ichthyosaurs (who also had live birth), and pterosaurs (known to lay eggs), etc.
Being warm-blooded isn't that much of a surprise- we've known birds descended from warm-blooded dinosaurs for decades.
Yes, but plesiosaurs are not dinosaurs so it means yet another branch of reptiles were warm-blodded. There is also evidence that Pterosaurs were warm blooded. Given how far back these branches had a common ascestor, the question becomes: why are crocodiles not?
If memory serves, I recall hearing that sharks run the gamut from plain oviparous through to placental warm-blooded viviparous.
Ah, yep, here's Google to the rescue.
Sometimes I run across news about discoveries where the commentators are all surprised, but in ways that make me think we need to get over ourselves :) as the utmost pinnacle of evolution or some such nonsense and just realise that we are no more than a combination of various biological strategies that had already been "invented" in numerous other branches of life. We're just a happy accident of much larger processes.
Cheers,
"What in the name of Fats Waller is that?"
"A four-foot prune."
By making comparisons with modern animals, such as whales, which give birth to larger, single young and then go on to care for them, Dr O'Keefe and his colleague, Luis Chiappe from the museum, attempt to infer something about plesiosaur behaviour.
... plesiosaurs, the authors suggest, might have been doting parents.
But Dr Smith was less convinced. He said that it was "certainly quite possible... but is very speculative".
Of course it's speculative, but it's still plausible. I would expect any animal who gives birth to one young at a time to spend time with its offspring until the offspring is strong enough to survive on its own.
The more we learn, the more it seems to me that different epochs of life on Earth were in many ways much more familiar than we used to believe. If only we could see into the past...
A little off topic...
When you get right down to it, behaviour doesn't fossilise
True, mostly. But sometimes we get very lucky... Velociraptor vs. Protoceratops. This gave some insight to how velociraptors used their big claws. (For gripping and stabbing, not slashing.)