Comments on: Extinction of the Old, Evolution of the New: What really happened to the dinosaurs?

By: Vikrant

Vikrant — Fri, 28 Sep 2012 19:26:26 +0000

There was a compendium issue of paltgonaoloey in the Anatomical Record in 2009 which included a fascinating paper by Edith Schachner showing that dinosaurs had lungs with a one-way through air circulation like birds, in contrast to the tidal air circulation that we have. The bird / dinosaur one-way system, which employs air sacs in bones, is TEN TIMES more efficient than ours. Bird lungs dont move out and in like ours with breathing. They have a rigid shape, and are smaller than ours relative to body size. But their much greater efficiency allows them to accomplish the aerobic feat of flying long distances, impossible for mammals.That dinosaurs also had these bird-like lungs (birds are of course dinosaurs, the surviving or crown group) means that they literally would have RUN RINGS AROUND any mammalian ancestors that they encountered. The more agile ones like the struthiomimids and raptors would probably have run indefinitely without tiring. Thus our thecodont ancestors had to sit out 150 million odd years as nocturnal rats waiting for the dinosaurs to go away.Our ancestors had to sit through three or four mass extinctions in fact before our moment came. The biggest was the Permian-Triassic, a heat event. Flood basalt eruptions in Siberia realised the wildest AGW dream-nightmare of catastrophe, with prolonged massive volcanism and atmospheric discharge resulting in warming leading to catastropic ocean anoxia, almost total extinction in the sea and 80-90% on land. However two groups that survived, Therapsids and Thecodonts, developed into the dinosaurs and (eventually) mammals respectively. The dinosaurs were well heat adapted, especially with their efficient lungs. So the mammalian precursors lost out but did not die out.The next catatrophe was also a heat event, the Triassic Jurassic, basically the start of the separation of America from Europe-Africa, and the opening up of the mid-Atlantic ridge. Again big-time volcanism, acute warming. Again the dinosaurs did well. (But we held on.)However During the cretaceous, a general cooling started. Also there were cold snaps (as the dinosaurian BBC would have called them) such as the one described in this article from Plymouth. This began to stress the dinosaurs who preferred it hot. This may be one reason why some dinosaurs tended to larger size in the Cretaceous like T Rex. (Although sauropods were big in the Jurassic). So some good news for the rat-like mammals-in-waiting.Then came the end-Cretaceous disaster, the Chikxulub meteor impact. Finally a cold event extinction. The dinosaurs perished except the dinosaurian ancestors of the birds. Mammals with their fur and thermoregulation survived, and, following brief competition with some monster-chicken like bird predators, emerged finally as the dominant land animals.Climate continued to cool in the Tertiary further playing to mammals’ advantages. Eventually the current glacial period developed (landmass surrounding a north polar sea).But if AGW is correct and CO2 release reverses 200 million years of cooling, then maybe the tide will turn again? Perhaps the birds will evolve back into dinosaurs?A major physiological advantage of dinosaurs over say humans relates to playing the organ. A human organist has a balance problem, he uses feet for the pedal bass notes and hands for the keyboard,and leans forward with no counter-weight. A dinosaur, realising development toward bifocal eyes, opposing thumbs and intelligence etc.. (e.g. Struthiomimus, Compsognathus etc.) would not have this problem. The leg and arm claws, though fewer in number (3-4 rather than 5) would still play the pedals and keyboard effectively, and the tail would counter-balance the whole organist. Thus the complete realisation of Bach’s musical creativity awaits this significant climate warming and consequent re-adjustment of life-forms.

By: DDeden

DDeden — Thu, 28 May 2009 15:16:00 +0000

http://news.yahoo.com/s/ap/20090528/ap_on_sc/us_sci_volcano_extinction_2

I’d suggest looking for the initial cause at the antipode, a cosmic impact, possibly in deep sea.

By: DDeden

DDeden — Mon, 18 May 2009 20:22:56 +0000

Mass extinctions @ 14 minutes: flood basalts, note the picture of Earth basalt flows, oddly symmetrical. I figure flood basalts are antipodal to comet impacts, release of gases caused mass extinctions.

By: Ed Pardo

Ed Pardo — Tue, 12 May 2009 11:43:49 +0000

DDeden
Yes. There was another similar event as well: The Atlantic Traps. The problem is that if it was also the result of an impact, it would be very difficult to find as it would have been somewhere mid Pacific. Fascinating subject no?

By: wybory sondaze demokracja

wybory sondaze demokracja — Tue, 12 May 2009 09:13:17 +0000

So we are waiting for another “boom”.

By: DDeden

DDeden — Mon, 11 May 2009 20:40:11 +0000

If the Deccan antipode was the (terrestrial/aerial) dino killer then the PT ocean “impact” should be called ocean “explosion”, since it was presumably the Siberian antipode of the Bedout impact. This would be the equivalent of the ocean floor at the antipode massively increasing output of benthic smoker vents, changing both water temperature and chemistry, and later on air temperature and chemistry.

By: Ed Pardo

Ed Pardo — Sun, 10 May 2009 17:12:14 +0000

DDeden
Very similar but somewhat more devestating. Peter Ward did an excellent book called “Gorgon” about his research in the Karoo of Africa. The PT boundary is easily accessable there.

He did not talk about Bedout however as it was not known at the time of printing. He does talk a little about the traps however, but not very much.

By: DDeden

DDeden — Sun, 10 May 2009 02:10:38 +0000

A milk jug, as in plastic, full of milk or water. I’d guess 70ma NAmerica passed the tropics northwards resulting in reduced species diversity of ‘cool’ blooded animals due to poor adaptation in colder climate, while burrowing mammals handled the cold well.

The PT event sounds similar to the KT event.

By: Ed Pardo

Ed Pardo — Sat, 09 May 2009 15:48:10 +0000

Sorry – 90 of species should of course be 90% of species

By: Ed Pardo

Ed Pardo — Sat, 09 May 2009 13:46:07 +0000

Greg
Maybe they did. Maybe that is why Bakker sees the decline in N.A. fauna from 70mya through the KT.

There is a parallel at the PT event and the same argument. Bedout crater impact occurs before the Siberian Traps. It was much more of an ocean impact than Yucatan and the marine extinction around 90 of species. Then later a 70% extinction of terrestrial species (just a little more then the KT event) with the eruption (and continuing flow) of the Siberian Traps on the other side of the globe.