Sunday, May 27, 2018

"Opposite Birds:" Why Being Grounded May Have Been the Counterintuitive Key to Survival


     The asteroid impact that caused a mass extinction 66 million years probably also triggered the collapse of forests worldwide, a new investigation of the plant fossil record concludes. 



     Needing trees and extensive plant cover for nesting or food could have been a fatal drawback for winged dinosaurs, including some ancient birds.


        Here is the caption for the diagram above: 

         "Ancestral Ecological Reconstructions Reveal Bias toward Non-arboreal Birds across the K-Pg:

      Bayesian ancestral ecological reconstructions (AERs) indicate that the most deeply diverging crown bird clades, including Neornithes (all crown birds), Neognathae (Galloanserae + Neoaves), and Neoaves, were ancestrally non-arboreal (pp > 0.99 for each node), with numerous independent transitions toward arboreality arising in the early Cenozoic, presumably after global forests had recovered from the Chicxulub impact. Concentric background rings demarcate geologic periods: the inner gray circle at the center indicates the Late Cretaceous, with the K-Pg boundary (66.02 Ma) indicated by the red dashed line; the white ring indicates the Paleogene (66.02–23.03 Ma), separated from the Neogene (23.03–2.58 Ma) by the dashed blue line. Tips extend to the present. Pie charts at the nodes indicate SIMMAP posterior probabilities for ancestral ecology, under our model. Branch colors represent a single randomly sampled stochastic character map from a posterior sample of 1,000 maps. The underlying phylogeny and taxonomy follow; qualitatively identical patterns are inferred using an alternative phylogenetic hypothesis."

       Reconstructing the ecology of ancient birds suggests that modern birds descended from species that survived because they could live on the ground, a research team proposes in the June 4, 2018, Current Biology.



      “You probably would have died anyway regardless of habitat,” says study coauthor Dr. Daniel Field, an evolutionary paleobiologist at the University of Bath in England. “But if you could get along on the ground, you at least had a shot at surviving across this devastated landscape.”

     The shock wave from the strike probably flattened trees within a radius of 1,500 kilometers, Dr. Field says. Wildfires ignited around the planet and then came the acid rain. Clouds of ash and dust may have darkened the sky for several years, and researchers suspect that photosynthesis waned. Yet some lucky birds, but no other dinosaurs, survived the hellscape.


     For clues to what made a survivor, researchers turned to fossilized pollen from before and after the fiery impact. Abundant kinds of flower-bearing and cone-bearing plants left pollen just before the asteroid hit and again starting about a thousand years afterward. In between those times of diversity, however, ferns dominated, the team notes. A kind of “disaster flora,” ferns (making spores instead of flowers and seeds) do well at recolonizing land. Seed plants, however, weren’t thriving.



     Analyzing evolutionary histories of modern birds supports the idea of tree dependence as a vulnerability for the earliest fowl, the researchers say. Specialists in bird evolution now generally agree on the lowest, oldest branches of the bird family tree, Field says. The bottommost one, for instance, includes such modern species as ground-dwelling ostriches and smaller, flight-capable birds called tinamous, which might be more like the ancient birds that dodged extinction.



     Working backward along these low branches, researchers used fossils and known bird traits to reconstruct the most likely lifestyles of the earliest survivors. These probably weren’t tree-dependent birds, the researchers conclude.



     The glory days of dinosaurs had had plenty of flying tree-dwellers. So far, paleontologists have identified at least 80 kinds of what are called “opposite birds,” the Enantiornithes. “If you saw one flying around today, you’d say, ‘Well, that’s a bird,’ ” Field explains. Their feet looked like those of birds that perch on tree limbs, so he’s not surprised that a fossil of an opposite bird from this probably arboreal group has never been found in rock formed after the dinosaur doomsday.



     What did happen, however, was that when trees and forests came back after the disaster, birds quickly evolved arboreal lifestyles, the team says.



     Many people don’t realize that birds almost died off during the mass extinction, too, says paleontologist Stephen Brusatte of the University of Edinburgh who has studied bird evolution but was not involved in the new study. What let the few survivors squeak through, he says, has been a mystery for a long time. The whole scenario of a ground-dweller’s advantage and then a return to the trees “makes a lot of intuitive sense.”

     Essentially, surviving on the ground, without much flying, for awhile may be what ultimately made the later arboreal environments so rich with modern-day birds.

No, er, YES, GROUSE about it!
Steph

31 comments:

  1. I had a friend who would grouse about your use of hellfire for his birthplace of Bishop CA. From a higher resolution photo the flares at the lower left look to be in human made structures.

    Notwithstanding, is there discussion in the article about the path of the numerous non-arboreal birds that are nonetheless excellent flyers? Coastal birds come to mind - grebes, gulls, egrets, herons, cormorants, boobies, frigate birds, albatrosses, puffins, plovers - are all good to excellent flyers, and generally don't hang out in trees. Same with ducks, geese, swans, etc., though I think those are on a different evolutionary path. And the arctic tern, perhaps the greatest flyer of all, is similarly non-arboreal due to its home field choice.

    Also, I found the evolutionary nesting circle interesting, here's a link to a higher quality version. My eagle eyes can't read the details in yours (another grouse).

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  2. Eagle-eye-eco! I have been to Bishop also and would not call it hellfire. It's what popped up on DDG.com when I entered hellfire, though. No cameras around 66 million years ago. . .

    Interesting point about shore birds. I wonder if flying was somewhat limited with all the meteroic impact/fire particulates in the atmosphere.

    Thanks for the better link. I, too, was fascinated by the sheer numbers of different birds on that chart!

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    1. Btw, I added the description for the chart to the text above. I meant to do so originally. So much information in that one diagram!

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  3. The different clade classifications under the main heading of the Wikipedia article on Enantiornithes are somewhat confusing. . .

    Avialan brains!

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    1. I guess it makes sense that the avian tree has so many branches, they've been at it for a while. And as Darwin showed us with finches they can change relatively quickly and in a small land area.

      Somewhere I read that there is no conclusion yet from the DNA; there are many twists to the genetic linkages, so they're still winging it.

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  4. Some people want inflatable dolls, but for others.....

    Reminds me of this classic.

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  5. The dogged reporting was just a puff piece.

    What we really need is a wall around our solar system.

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    1. Post wrote a nice obit, NYT was a little curt with theirs.

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    2. Yes, very curt. It was odd.

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    3. My favorite story was from a Smith club rugby player who wrote a note to Jill about the time it took from practice to put up/take down the goals every day. Jill invited her for breakfast. They talked about lots of things and little about rugby. The next week, there were permanent goals set up on a new dedicated field. Jill had quietly paid for all of it herself.

      She was only 40 when she became Smith's President. I didn't know how young that was when I was there. . .

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    4. Glad to see that the NY Times wrote a more extensive obit today.

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    5. NYT round 2 did her justice. I suspect the first one was put up very quickly after they got notification, no time to do the research for the more extensive piece.

      I understand the major newspapers have advance prepared obituaries for famous and very old people (George H.W. Bush for example) so they can run them right away - a morbid reality. I suspect Dr. Conway was not at that level.

      I've only personally known a couple of people who got full obit stories in the NYT, and both took a few days to appear.

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  7. I certainly enjoyed this excerpt from a The New Yorker about “The President is Missing:”

    “Fauna, for some reason, bring out the very best in the makers of this book. The stealthy assassin, seeking a forest perch from which to shoot, has a Bambi moment: “Along the way, little animals bounce out of her path.” On a more rueful note, “Augie looks at me like a lost puppy, in a foreign place with no partner anymore, nothing to call his own except his smartphone.” So true, and so very sad. It’s not enough to give a dog a phone.”

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    1. Probably was a mistake to give Anthony Lane an advance copy of the book. Clinton has certainly been off his game on the talk shows this week. Time for a new Democratic torch bearer, and I don't mean Hillary.

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    2. jan, I agree. The fact that Bill Clinton conflated an apology to Monica Lewinsky with the "$16,000,000 in debt when he left the WH" was bizarre. He doesn't get it still.

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    3. Bill Clinton is also a self-involved narcissist, he's merely able to control his public expression a little bit better than the current occupant. Just a little bit.

      I wonder if all presidents are some form of sociopath? Maybe not Jimmy Carter, but the others?

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    4. eco, I don't know. Barack Obama?

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    5. It dawned on me today that 45's obsession with the American flag may be tied to his birth being on Flag Day.

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    6. I agree, Steph, that Obama, like Carter, wasn't a sociopath. He was able to be a lot more effective, too, e.g., Obamacare, banking and consumer finance reform, though, alas, those seem to be too easily undone.

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    7. Okay, maybe Obama isn't a sociopath - I considered that but got bored with it. Dwight Eisenhower probably wasn't a sociopath either.

      To Trump and the flag: concurrent dates may have something to do with it, but I think the larger narrative of his life is his position as a salesman (yes, it could be a saleswoman, but the men dominate in grift), it's all he really knows how to do. And salesmen have no principles, no morals, no belief structures; their only thought is to "make the deal."

      And for Trump the product is himself, and he will mold himself to whatever forces he think will give him the biggest victory - if this were a different time he would pose as a liberal (as he has done). In that context the salesman will seize upon any symbolic gestures that will ring in the ears of their "marks" (to use the grifter's term). He knows the flag is an emotional touchstone with many people, so he (like both Bushes) drapes himself in meaningless appearances. Same with religion - does any thinking person for a moment believe Trump has devotion to anything other than himself?

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    8. Glad you concur about Obama.

      I completely agree that 45 is only devoted to 45.

      As to salesmen/saleswomen, I think it depends on what one is selling. I had great success selling peaches for my friend at the Farmers' Markets. People would bring their friends over to say "There's the peach lady, she'll make you fall in love with those peaches." The peaches did all the selling, though. . .

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    9. Maybe Obama had a slight socio-pathology in wanting to please everyone, and at times wouldn't stand up strongly. Certainly not dangerous like Cult45, but still problematic.

      The heart of the grifter salesmen is they sell things people don't want or are not good for them.

      Probably hard to do with peaches.

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  8. It's fascinating to see how toddlers process unfamiliar information. I was video chatting with my granddaughter on Sunday. She was happy to identify the dog appliqu├ęs on her shirt. Her father (unwisely, I thought) asked her what was on grandpa's shirt. I hadn't thought about it, but I was wearing a t-shirt with a dog skeleton on it, a black lab, in profile. (Long story...) I know she's had no exposure to skeletons and was hoping to avoid a conversation involving dead dogs. She thought for a moment, considered those ribs striping down, and announced, "zebra ".

    It reminded me of an interaction I had with her father when he was just about her age. I was giving him a bath, soaping him up while reviewing some anatomical vocabulary, singing while touching, "the leg bone connected to the knee bone, knee bone connected to the thigh bone, thigh bone connected to the...". I touched his hip. Didn't know whether he knew that word. He guessed, "diaper bone?"

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    1. jan, your granddaughter is very wise.

      Wonderful diaper bone story, too. Young geologists respond similarly, instead saying "diapir bone?"

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    2. I've long wondered whether Asians (e.g. Chinese) have a different capacity for visual memory and processing of form? Their written language requires memorization of many thousands of individual characters that represent words/ sounds, whereas many (most?) other written languages combine a relatively few number of individual characters (letters) in a multitude of formations - often arbitrary relative to the individual characteristics - to represent words/ sounds.

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    3. The directional discussion was fascinating. I often give directions saying "turn north" or "go west one block." One friend would say "I don't know what that is; I barely know left and right."

      My hunch is some Asian folks may have a better directional sense due to their expanded visual memory. . .

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  9. New post on "Precambrian Fossil Obama coronatus: Sessile Be De Millions?" is now up.

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