Lack of Females May Have Done in Dinosaurs

Oddy Enough - Reuters ^ | 2004-04-21

[Ichneumon]

2 problems with this theory: 1. Current data suggests dinosaur physiology to be more like that of modern birds, and

"Like" modern birds does not mean "identical to" modern birds. Under the right conditions even a small difference can be a critical one.

2. Large reptiles, like crocodiles, survived.

Read the article, they covered that.

I think that I remember seeing a program where a major paleontologist commented on the declining diversity amoung dinosaur species BEFORE the asteriod impact event 65 million years ago. I guess that science writers can't get past their disaster-theory -- Just easier to sell to us poor, dumb, ignorant masses

Or maybe the "dumb, ignorant masses" aren't aware that several different factors can all contribute to an extinction, it's not a matter of "one cause which excludes all else". Few extinctions are due to *one* single thing acting alone -- they're usually due to a combination of things which together stack the odds sufficiently against the species to do it in.

If dinosaurs were already declining due to some other factor (e.g. climate change, competition from mammals, etc.), then they'd be more vulnerable to a major event like a large asteroid strike. Either one alone probably wouldn't have wiped them out. For example, perhaps without a prior climate-driven decline, an asteroid strike wouldn't have been able to knock off *all* the dinosaurs and a few hardier species would have survived to present day along with the crocodilians, etc.

[lilylangtree]

This explanation rivals the explanation for the gooney birds in "Ice Age". As one male gooney said to the other while watching a line of gooney birds jump over the cliff chasing a watermelon, "there goes our last female."

[Junior]

I did a quick web search.  The ichthyosaurs were already extinct well before the end of the Cretacious:

Ichthyosaur Page

Ichthyosaurs swam in the Mesozoic ocean when dinosaurs walked on land. To be precise, they appeared slightly earlier than dinosaurs (250 million years ago versus 230 ma) and disappeared again earlier (90 ma versus 65 ma).

They, and the plesiosaurs, were aquatic reptiles, not dinosaurs (there is a bit of a difference).  The plesiosaurs evidently lasted right up to the end of the Cretacious.  It is possible that a general collapse of the aquatic ecology caused by the die-off of algae and the itty-bitty critters that lived on it and cascading up the food chain, would have killed off these top-niche predators.  Sharks survived, but they weren't necessarily large animals.  The megaladon comes much later in the fossil record.

[CholeraJoe]

Kinda reminds me of the Dodo birds in "Ice Age." "OOPs there goes our last female."

[Ichneumon]

All T-rex's look gay. I mean, what's up with those arms?

Hmm, you may be on to something:

[white trash redneck]

I saw this on the Fox News crawl right after an article on same-sex marriage. I nearly fell out of my seat laughing. Looks like gay marriage was an issue in the Pleistocene era too!

[snooker]

I wonder, global warming, maybe it's bad for 'rats? Could be a heck of a new world if it were.

[Ichneumon]

In mammals, if a baby gets an X and a Y chromosome, it will be male and if it gets two X chromosomes it will be female, with a few very rare exceptions. Similar mechanisms work for birds, snakes and some reptiles such as lizards.

Genetic trivia: In mammals (including humans, of course) the XX form is female and the "mixed" XY form is male. But in birds it's "backwards" -- the male birds have the matched "AA" sex-determining genes and the females have the mixed "AB".

[Ichneumon]

Kinda reminds me of the Dodo birds in "Ice Age." "OOPs there goes our last female."

I love that movie, but they shouldn't have left the impression that dodos went extinct during the ice age. Instead they went extinct rather recently, in the mid 1600's.

[FreedomFarmer]

All T-rex's look gay. I mean, what's up with those arms?

Soccer causes extinction.

"You, Rex...Breeding Red Card!"

[Modernman]

Hmm.... Based on a five minute search on Google, some claim Ichtyosaurs and Plesiosaurs went extinct at the same time as Dinos, other claim they died out shortly before.

[Ichneumon]

Kinda reminds me of the Dodo birds in "Ice Age." "OOPs there goes our last female."

Movie trivia: In that scene, when Manny and friends ask for one of the watermelons, the dodos say:

Dodo: "If you weren't smart enough to plan ahead, then doom on you!"
Other Dodos: [chanting] "Doom on you! Doom on you! Doom on you!"

"Doom on you" may seem like a stilted phrase, but that's because it's an inside joke. The English phrase "doom on you" is phonetically almost identical with the Vietnamese phrase "Du-ma-nhieu", which means roughly "go f*** yourself".

Some English-speaking folks who are acquainted with Vietnamese cursing (like VN war vets, for example) sometimes use "doom on you" as a joking form of the original phrase, just as WWII vets sometimes used "mercy buckets" for "thank you" in parody of the French "merci beaucoup".

[lilylangtree]

Thank you. I just love that movie "Ice Age". I get a charge out of watching it everytime--the basic theme of how different species work together for the common goal appeals to me. Many thanks for the trivia and correcting me re dodo birds vice gooney birds.

[CholeraJoe]

Didn't know that. That phrase may soon enter my vocabualry.

[Junior]

When I get home tonight, I'll dig through my racks of "extinct megafauna" literature (it's a bit of a hobby of mine). I do remember reading somewhere that ichthyosaurs were pretty much defunct long before the dinosaurs went quietly into that long night.

[BCR #226]

http://unmuseum.mus.pa.us/searepti.htm

Check out the above link. Some survived until the end of the Cretacious.

Mike

[Lockbar]

Uh oh, bad news for China.

[Junior]

It doesn't specifically say the ichthyosaurs survived to that point, just that sea-going reptiles did. Plesiosaurs and mosasaurs indeed appear to have made it to the end of the Cretacious, but ichthyosaurs and IIRC, pliosaurs didn't.

[nuconvert]

demise of dinosaurs pong

[Junior]

Dunno if this is the type of thing you find interesting, but I figured I'd ping you anyway.