Thursday, April 29, 2010

Avian (Bird) and Pterosaur Breathing

The similarities of birds to pterosaurs is overwhelming. I will begin with the breathing system. Incredibly, pterosaurs and modern birds have the same unique and complex breathing system.
"Birds have one of the most complex respiratory systems of all animal groups.[39] Upon inhalation, 75% of the fresh air bypasses the lungs and flows directly into a posterior air sac which extends from the lungs and connects with air spaces in the bones and fills them with air. The other 25% of the air goes directly into the lungs. When the bird exhales, the used air flows out of the lung and the stored fresh air from the posterior air sac is simultaneously forced into the lungs. Thus, a bird's lungs receive a constant supply of fresh air during both inhalation and exhalation."

By utilizing a unidirectional flow of air, avian lungs are able to extract a greater concentration of oxygen from inhaled air. Birds are thus equipped to fly at altitudes at which mammals would succumb to hypoxia. This also allows them to sustain a higher metabolic rate than an equivalent weight mammal.[14]
For those who wish to know more about it, please check here.

Here are references to pterosaur breathing:

"In this report we present various lines of skeletal evidence that indicate that pterosaurs had a highly effective flow-through respiratory system, capable of sustaining powered flight, predating the appearance of an analogous breathing system in birds by approximately seventy million years."
"A 2009 study showed that pterosaurs had a lung-air sac system and a precisely controlled skeletal breathing pump, which supports a flow-through pulmonary ventilation model in pterosaurs, analogous to that of birds. The presence of a subcutaneous air sac system in at least some pterodactyloids would have further reduced the density of the living animal."
In current evolution theory thinking, birds evolved from dinosaurs. That means that according to the current "dino to bird" evolution thinking, birds and pterosaurs both evolved this unique and complex breathing system completely INDEPENDENTLY.
In evolution theory, this idea is called "convergent evolution". The similar characteristics are called "analogous".
In the position I am presenting in this blog, we do not need to rely on a (miraculous) convergent evolution. Modern birds
developed from pterosaurs so the development was not independent.
Postcranial skeletal pneumaticity and air-sacs in the earliest pterosaurs
Richard J. Butler1,*,
Paul M. Barrett1 and
David J. Gower2
Pterosaurs breathed in bird-like fashion and had inflatable air sacs in their wings
Posted by Darren Naish on February 18, 2009


  1. Just because the same feature arose twice in more than one group of animals, doesn't automatically mean that it is "miraculous". The unique breathing system that is shared by both birds and pterosaurs is an example of convergent evolution, nothing more, and nothing less. In fact, if you look more closely at the evidence, you can see that pterosaurs have practically NOTHING in common with birds, and that all of your supposed "similarities" are just homologies.

    In fact, judging by the nature of your post, I don't think that you have the slightest idea of how evolution — or science, in general — works. The dinosaur-to-bird theory isn't even really a theory, anymore. It's a proven fact. Birds ARE dinosaurs. End of story.

    The bottom line, here, is that your "theory" makes absolutely no sense, to me, and sounds more like the kind of garbage that a group of drunk teenagers would come up with.

    No offense, really. But I guess that's just the truth. Sorry.

  2. I disagree.
    You will have to present a case for your thinking.

  3. Um, I sort of ALREADY DID! And, now, I am going to present yet another case, for my thinking. For example, Dimetrodon and Spinosaurus both have a sail on their backs. Does that mean that Dimetrodon evolved into Spinosaurus! Hell, no! Dimetrodon was a synapsid, an ancestor of mammals. It was more closely-related to you and me, than it is to a Spinosaurus! Also, Ichthyosaurs look like reptilian versions of dolphins. So, does that mean that ichthyosaurs evolved into dolphins? Well, Hell, no!

    As you can clearly see, convergent evolution is the reason why pterosaurs and birds appear to be so similar to each other, in some of those aspects.

    Now, do you finally get what I'm saying?

  4. You sound like a teenager.
    I have spent over a year and have over 200 posts.
    I really am not interested in debating with a teenager.

  5. I have done a large amount of research on the connection of ichthyosaurs, mosasaurs and cetaceans, but I had not looked into creatures like Dimetrodon and Spinosaurus.
    It would be very interesting to look at the idea of Dimetrodon and Spinosaurus having an ancestor/descendant relationship. A preliminary analysis shows that that could be a very fruitful line of research.

    If anyone would like to work on any of these lines please let me know.

  6. Some initial reference material:
    "It [Dimetrodon] is classified as a pelycosaur"
    "Primitive synapsids are usually called pelycosaurs"

    Dimetrodon is a genus within Sphenacodontoidea
    Temporal range:
    Late Carboniferous–Middle Permian, 303–0 Ma

    Spinosaurus is a genus within Megalosauroidea.
    Temporal range: Middle Jurassic - Early Cretaceous, 170–93 Ma

    A preliminary analysis indicates that the timing could work for an ancestor/descendant relationship.

    "Dinosaurs (including birds) are archosaurs, like modern crocodilians. Archosaurs' diapsid skulls have two holes, called temporal fenestrae, located where the jaw muscles attach, and an additional antorbital fenestra in front of the eyes. Most reptiles (including birds) are diapsids; mammals, with only one temporal fenestra, are called synapsids; and turtles, with no temporal fenestra, are anapsids. Anatomically, dinosaurs share many other archosaur characteristics, including teeth that grow from sockets rather than as direct extensions of the jawbones. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodilians sprawl out to either side."

    "At least two pelycosaur clades independently evolved a tall sail, consisting of elongated vertebral spines: the edaphosaurids and the sphenacodontids."
    "Synapsids evolved a temporal fenestra behind each eye orbit on the lateral surface of the skull. It may have evolved to provide new attachment sites for jaw muscles. A similar development took place in the Diapsids, who evolved two rather than one opening behind each eye."

  9. DIMETRODON (Synapsida, Pelycosaur) - synapsid?? (a temporal fenestra behind each eye orbit on the lateral surface of the skull)

    SPINOSAURUS (Dinosaur, Megalosauroidea) - diapsid?? ( two holes (temporal fenestra) in each side of their skulls)