Birds of unusual size

Because today is election day, and if I stress any more about the results I'm going to burst into flame, today at Skeptophilia headquarters we are focusing on: enormous birds from Madagascar.

There has been a lot of research recently on "Elephant Birds," which (as you might expect from the name) were not your average chickadee.  They belong to the family Aepyornithidae in the clade Palaeognathae, which also includes ostriches, tinamous, cassowaries (better known as the Australian Badass Death Bird), and kiwis.  The name "Palaeognathae" means "old jaw," because they retain the structure of the palate and jaw closer to their reptilian ancestors.  (All the other birds are in the clade Neognathae -- "new jaw.")

Elephant Birds' closest living relatives are kiwis, which is kind of amazing given the fact that the largest species was four meters tall and weighed an estimated 650 kilograms, while kiwis look like bizarre walking footballs with feathers.  Sadly, the Elephant Birds were all extinct by 1,200 C.E., and no one knows exactly why, but overhunting by humans is a definite possibility.

Reconstruction of Aepyornis maximus [Image licensed under the Creative Commons Acrocynus, Aepyornis maximus 01 L.D., CC BY-SA 3.0]

The most recent study was of the brain cases from fossilized Elephant Birds, and from this they concluded that the whole group was likely to be nocturnal animals that had poor vision and relied largely on their sense of smell.  It makes sense; the same is true of kiwis.  The logic behind the conjecture is explained in the paper "Nocturnal Giants: Evolution of the Sensory Ecology in Elephant Birds and Other Palaeognaths Inferred from Digital Brain Reconstructions," by Christopher R. Torres and Julia A. Clarke, of the University of Texas at Austin.  The authors write:

Palaeoneurological studies can provide clues to the ecologies and behaviours of extinct birds because avian brain shape is correlated with neurological function.  We digitally reconstruct endocasts of two elephant bird species, Aepyornis maximus and A. hildebrandti, and compare them with representatives of all major extant and recently extinct palaeognath lineages.  Among palaeognaths, we find large olfactory bulbs in taxa generally occupying forested environments where visual cues used in foraging are likely to be limited.  We detected variation in olfactory bulb size among elephant bird species, possibly indicating interspecific variation in habitat.  Elephant birds exhibited extremely reduced optic lobes, a condition also observed in the nocturnal kiwi.  Kiwi, the sister taxon of elephant birds, have effectively replaced their visual systems with hyperdeveloped olfactory, somatosensory and auditory systems useful for foraging.  We interpret these results as evidence for nocturnality among elephant birds. Vision was likely deemphasized in the ancestor of elephant birds and kiwi.

A study earlier this year, by James P. Hansford and Samuel T. Turvey of London's Institute of Zoology, revised what we know about the group's taxonomy.  Their paper, "Unexpected Diversity Within the Extinct Elephant Birds (Aves: Aepyornithidae) and a New Identity for the World's Largest Bird," which appeared in Royal Society Open Science in September, identified a new species, the aptly-named Vorombe titan.

So this is all pretty impressive, considering that we're talking about a group of extinct birds whose most recent common ancestor with anything that's still alive was sixty million years ago, only five million years after a giant meteorite ended the dinosaurs' hegemony.  Another cool thing is that given how recently they became extinct -- only eight hundred years ago, give or take -- they're a possible candidate for a Jurassic Park-style resurrection.

Which would be amazing.  Of course, I'd prefer it to happen somewhere other than upstate New York.  We have enough trouble with fluffy bunnies in our vegetable garden, much less 650-kilogram ostriches on steroids who come out at night and hunt by their sense of smell.  And remember that these things are kissing cousins to the cassowaries.  We can't rule out their being ill-tempered, as well.

So maybe it's just as well they're extinct.  For one thing, if they were still around, it'd only be a matter of time before Donald Trump decided to train them to protect the borders, and the next thing we knew there'd be hordes of FX-17 Giant Flightless Tactical Assault Birds running amok in Arizona.  And heaven knows we don't want that.

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In writing Apocalyptic Planet, science writer Craig Childs visited some of the Earth's most inhospitable places.  The Greenland Ice Cap.  A new lava flow in Hawaii.  Uncharted class-5 rapids in the Salween River of Tibet.  The westernmost tip of Alaska.  The lifeless "dune seas" of northern Mexico.  The salt pans in the Atacama Desert of Chile, where it hasn't rained in recorded history.

In each place, he not only uses lush, lyrical prose to describe his surroundings, but uses his experiences to reflect upon the history of the Earth.  How conditions like these -- glaciations, extreme drought, massive volcanic eruptions, meteorite collisions, catastrophic floods -- have triggered mass extinctions, reworking not only the physical face of the planet but the living things that dwell on it.  It's a disturbing read at times, not least because Childs's gift for vivid writing makes you feel like you're there, suffering what he suffered to research the book, but because we are almost certainly looking at the future.  His main tenet is that such cataclysms have happened many times before, and will happen again.

It's only a matter of time.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]