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."

Comments

Nice

[geekoid]

More science, please.

Re:Nice

[SilverHatHacker]

Perhaps it's a microcosm of the scientific world at large, but most of our dinosaur knowledge is based on "this is the first idea that popped into my head when I saw the thing, so we'll call it true until proven otherwise". The iguanadon, for example, was thought to have horns on its nose until a full skeleton was discovered and it was revealed that they were thumbs. Don't get me wrong, I don't care that we're creating imperfect theories based on limited knowledge which are expanded when more is discovered; that's how science works and how it should work. What I find to be particularly annoying is when these theories are taught as unchallenged fact. There was one species of dinosaur that was "discovered" in the form of a single bone, but sketches of the full animal were showing up in textbooks. If all you have is a single bone, at least put an asterisk beside the picture please! Maybe our knowledge would advance faster if we knew what exactly we knew and what we don't know.

Re:Nice

[martin-boundary]

Dear Mr Science,

I too am intrigued by these pleasuresaurs, and would like to subscribe to your newsletter.

Livebearers

[Oswald McWeany]

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.

Ovoviviparous?

[SMoynihan]

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!)

upsetting science

[macraig]

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?

Re:No different from sharks.

[Anonymous Coward]

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.

Re:Plesiosaurs are not dinosaurs

[dryeo]

I was recently reading somewhere that crocodiles (and other Crocodilia) were at one time warm blooded. The evidence being that they have a 4 chamber heart like most warm blooded animals. It was theorized that they reverted to being cold blooded at some point in their evolution.
Interestingly crocodilia also have a neo-cortex and diaphragm unlike all other extent reptiles.
As usual Wikipedia has a bit about it, http://en.wikipedia.org/wiki/Crocodilia#Internal_organs

Placental sharks

[zooblethorpe]

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,