Thursday, February 28, 2013

30 Day Dinosaur Drawing Challenge: Day 1

I'm usually pretty bad at keeping up with these 30 Day Challenges, so let's see how long I can keep this one going. The challenge can be found here.

Day 1: Favorite theropod
I'm not really a theropod kind of guy. Of course, they're awesome, and I'm fascinated by them. But I don't obsess over them the way some do. That's why my favorite theropod is also one of the most bizarre and un-theropod-ish.

My favorite theropod is Therizinosaurus cheloniformis. I think I love this animal so much because we have so much in common: a big, weird creature, with big arms and a huge pot belly. Here's my reconstruction of Therizinosaurus. I'm not sure I like how the color came out, but what's done is done.

Tuesday, February 26, 2013

The insatiable appetite of King Whale-head

The weirdness of the shoebill goes far, far beyond its taxonomy and evolution. Visually, they resemble something resurrected from the depths of prehistory. Despite its prominent bill and captivatingly unique appearance, the shoebill is a reserved animal; in fact, while many may find them ugly or comical, I think they have a certain stoic beauty about them. They are truly the wise, old fishermen of the bird world; standing motionless for hours on end, waiting for fish to come to the surface.
A shoebill in its preferred fishing spot: perched on floating vegetation. Photograph by Jnissa, from Flickr.
Most piscivorous (that is, fish-eating) birds display certain adaptations for hunting their prey, whether it be a lance-like bill, sharply-hooked talons, spacious pouches, or paddles. But the shoebill is, not surprisingly, an anomaly: its bill is stout and broad, rather than slender to pierce through water; their toes are unwebbed and they neither dive nor swim.

Shoebills fill a very specific niche: they prefer to hang out around poorly-oxygenated waters, areas in which fish such as catfish and lungfish often need to rise to the surface to gulp down air. They are not so much unequipped for fishing as they are extremely well-equipped for angling in different waters.

A shoebill ruins some poor fish's day. Photograph by Morgan Trimble.
Their fishing tactic is less like that of a spear-fisherman, and more like a catfish noodler: they don’t simply pluck fish from the water, they go all in. They simply wait for a fish to take a breath and then launch into the water in a flurry of splashing feathers, killing them with a nail-like projection on the end of the bill. The “hunt” usually consists of loss of balance and, in some cases, entanglement with foliage. Some individuals have had to free themselves from vegetation before they can even swallow their meal. The shoebill’s broad and powerful beak allows them to tackle a wide range of prey, ranging from snakes, turtles, and young crocodiles to rodents, young waterfowl, and, apparently, an antelope calf.

Did you catch that last one? I’ll say it again: it ate a baby antelope.

The business end of a shoebill. The nail-like projection on the tip of the bill can be seen clearly in this photo. Photograph by Makitani, from Flickr.
Yes, it’s true. There exists just one account of a shoebill feeding on a newborn black lechwe, a subspecies of wetland-dwelling antelope found throughout central and east Africa. I’m a little unsure what to make of this observation: the shoebill is certainly well-equipped to kill such prey, but it would be impossible for the bird to swallow, and it lacks the proper equipment with which to tear its prey apart. Perhaps the shoebill in question was observed feeding on a calf that had already died. No matter what the observation actually was, this is the only account of a shoebill feeding on prey of that size, and it was made in 1961. It is not typical shoebill behavior to chase around antelope. Lungfish are easy enough to catch.

Thursday, February 21, 2013

The stork that is a pelican

In the mixed papyrus swamps of central-eastern Africa, there lives a large bird by the name of Balaeniceps rex: the king whale-head. No one really calls it that, though, as it had a more comical common name: the shoebill, for its beak’s likeness to a large piece of footwear.
The majestic shoebill Balaeniceps rex. Not to be confused with Big Bird. Photograph by Bill Gracey.
The shoebill is a bizarre bird, and while I was originally going to write about just how odd they are, I came across something even more puzzling:  how they are classified and their mysterious evolutionary history.

In 1852, Gould described the shoebill as an “aberrant pelican,” and his claim wasn’t far off from recent studies. Anatomical characteristics led to the placement of the shoebill in an outlying position, sharing a common ancestor with frigatebirds, pelicans, gannets, anhingas, and cormorants. (Mayr, 2003)

The most recent genetic analysis declares that pelicans are, in fact, the closest living relatives of the shoebill. Also included in this monophyly are herons and ibises, and even more distantly, cormorants and storks, though the latter is far removed from the shoebill. (Hacket et. al., 2008) However, the shoebill has only recently become settled, if it is truly settled, in its position in the great ornithological cladogram. Over the years, it has been regarded as closely related to storks, ibises, and New World vultures; monophyletic with herons (which is not far off, according to recent evidence); or offshoots of birds such as gannets, cormorants, and frigatebirds.
Another shoebill. Not much else to say 'bout this one. Photograph by _yasa, from Flickr.

Origins of the stork-pelican
It’s funny; I grew up referring to the bird as a shoebill stork, which is one of the species’ common names, and all these years later I learn that it’s just a big, Muppet-looking pelican. Okay, not exactly. But if shoebills and pelicans share a common ancestor, when did the two groups diverge? Clearly, the body shapes of these two families of birds are extremely different. The disappointing truth is that we don’t know much about the evolution of the shoebills.

Only two relatives of the shoebill are known from the fossil record, both hailing from Egypt: the Oligocene species Goliathia andrewsii, and the Miocene Paludavis. G. andrewsii probably very similar to the modern shoebill; in fact, it may be classifiable as the same genus. It lived in an environment very similar to preferred shoebill habitat today, and shared its wetland home with catfish and lungfish, both preferred prey items. At about the same size as the extant shoebill, and possibly belonging to the same genus, it appears that modern-looking shoebills had already evolved very early in the Cenozoic. (Rasmussen et. al., 1987)

Regardless of its relationships to other birds, one thing is certain: the shoebill is just plain weird. In the next post, we'll examine the behavior and biology of this oddity.

Hackett, S.J.; Kimball, R.T.; Reddy, S.; Bowie, R.C.K.; Braun, E.L.; Braun, M.J.; Chojnowski, J.L.; Cox, W.A.; Han, K.-L.; Harshman, J.; Huddleston, C.J.; Marks, B.D.; Miglia, K.J.; Moore, W.S.; Sheldon, F.H.; Steadman, D.W.; Wiit, C.C.; and Yuri, T. 2008. A phylogenomic study of birds reveals their evolutionary history. Science 300, doi:10.1126/science.1157704

Mayr, G. 2003. The phylogenetic affinities of the shoebill (Balaeniceps rex). Journal für Ornithologie 144, 157-175.

Olson, S.L.; Rasmussen, D.T.; and Simons, E.L. 1987. Fossil birds from the Oligocene Jebel Qatrani Formation, Fayum Province, Egypt. Smithsonian Contributions to Paleobiology 62.

Monday, February 18, 2013

A few things I bet you didn’t know about elephants

Elephants are probably the most recognizable animal on the planet, but we never really stop to think about just how unique they are. They are equal parts brain and brawn, and have highly sophisticated social patterns; they display lateral preferences (being left- or right-tusked, for example); they can lift objects weighing almost 800lb (~363kg), and can crack the shell of a peanut without damaging its contents.

Here’s a list of some of the things that make elephants so damned amazing. Despite their familiarity, they are truly alien animals.

They are left- or right-tusked. Their “master tusk” is shorter and more worn than the less-used one.
A left-tusked elephant.
They’re also left- or right-trunked. Elephants only have one trunk (duh), but they seem to show preference in twisting it to one side or the other when grasping objects.

They have an extra “toe.” It’s not a true toe, though. Hence the quotation marks. Much like how pandas have an extra “thumb” to assist them in gripping bamboo, elephants have evolved a false toe to help with weight distribution.

They permanently walk on tiptoe. Though their feet may look big and flat, the bones in their hands and feet are balanced on their toes. The feet get their distinctive rounded shape from pads of fat located just under the bones.
Diagrams showing the bones in the hands and feet of elephants. The weight is balance on the tips of their toes, which are supported by large pads of fat. The bones highlighted in white are the extra "toe" which assists in weight distribution.
They get stressed when their matriarch passes away. A study conducted in captivity showed that stress hormones increased greatly after the passing of a herd’s matriarch. The matriarch is the eldest female in the group, and their age has been shown to be linked to a heightened sense of protection for the herd. (McComb et. al, 2011)

No matter if other females are present, the matriarch’s daughter always inherits the herd. Even sisters are second in line to the daughter of the matriarch. Kind of like the beginning of The Lion King. Be prepared…

They’re self-aware. When they are presented with a mirror, they know they’re looking at a reflection of themselves, not just another elephant. This is a trait found in many highly-intelligent species, including apes and dolphins.
This is Happy, an Asian elephant Elephas maximus. When presented in front of a mirror, Happy was able to touch that white "X" on her own head, rather than on the surface of the mirror, indicating her awareness that she was looking at herself.
Humans are selectively breeding them for shorter tusks. Well, indirectly. As more elephants are being poached for their ivory, males with shorter tusks are becoming more common. We aren’t so much breeding shorter-tusked males as we are selectively killing males with more impressive pairs. Since the mid-19th century, the size of African elephant tusks has halved. (Gray, 2008)

They are extremely interested in the bones and ivory of other elephants. Videos often show elephants “mourning” their dead. While scientists are still unsure the extent to which elephants feel emotion, experiments show that African elephants are much more interested in the bones of others, related or not, than they are to objects such as wood or the bones of other species. (McComb et. al, 2006)
A photo from Douglas-Hamilton et. al's research in Kenya. The collapsed female is Eleanor. You can see another female touching Eleanor with her foot. Other females look on.
They aid ailing members of their species, regardless of familial connection. Unrelated females will rush to the aid of an animal that has fallen. In one study done in Kenya, an individual named Grace helped an elderly female named Eleanor back onto her feet after she had collapsed. Eleanor fell again shortly after and eventually passed on. However, elephants of various different family groups investigated her body, touching it with their trunks and feet, and staying by her side even after her death.  (Douglas-Hamilton, 2006)

Douglas-Hamilton, I., Bhalla, Wittemyer, G., and Vollrath, F. 2006. Behavioural reactions of elephants towards a dying and deceased matriarch. Applied Animal Behaviour Science.

Gray, R.  2008, January 20. Why elephants are not so long in the tusk,

McComb, K., Baker, L., and Moss, C. 2006. African elephants show high levels of interest in the skulls and ivory of their own species, Biology Letters 2, 26–28.

McComb, K., Shannon, G., Durant, S.M., Sayialel, K., Slotow, R., Poole, J., and Moss, C. 2011. Leadership in elephants: the adaptive value of age. Proceedings of The Royal Society B, doi:10.1098/rspb.2011.0168

Thursday, February 14, 2013


Happy Valentine's Day, everyone! Hope everyone received their fair share of chocolates, flowers, cards, and candy. And if you're single, I hope you were able to post some snarky Facebook statuses!

Here's my Valentine to you all: the chasmosaurine Mojoceratops perifania living up to its name. How can you say no to a frill like that?

Wednesday, February 13, 2013

Time heals all wounds, even if you're extinct

Injuries are surprisingly common in the fossil record. Some specimens even get their fame from the amount or severity of their pathologies - the famous Allosaurus "Big Al," as well as the Tyrannosaurus "Sue" are both riddled with contusions and fractures which they carried with them in life as in death. We can tell by looking at these fossils if an animal died due to its injuries, or was able to recover and live a relatively normal, albeit more painful, life.
I was hoping to find this picture online! A pack (woo!) of Tyrannosaurus pursuing a herd of Edmontosaurus. The artist's signature is at bottom-right, but I can't read it. If you know who painted this masterpiece, please let me know.
Finding evidence of bite marks or scrapes on the fossils of deceased animals is not surprising - carnivore's gotta eat something, right? Numerous Triceratops fossils sport gashes and cuts from (big surprise) Tyrannosaurus teeth (though these did not heal - the prey was already dead), and some Edmontosaurus vertebrae display signs of healing after close encounters with the tyrant-lizard.

Yesterday, evidence of an even more fascinating brush with death was published. Skin impressions from the head of an Edmontosaurus revealed something truly remarkable: a scar.
The Edmontosaurus skull (top) and skin impression (bottom). The area highlighted in red represents where the animal was attacked. The scar can clearly be seen on the impression. From Rothschild and Depalma, 2013.
Now, a scar may not seem that exciting. Each of us (animals in general) has our fair share of them, caused by anything from cuts to scratching at chicken pox. But we seldom realize that scars are indications that our immune systems are working well, and that our body is working to patch up a minor tear or scrape so that we can move on. The Edmontosaurus in question not only had a brush with death, but it survived and healed to see another day in Hell Creek.

Fossilized skin impressions of non-avian dinosaurs are uncommon, but they are becoming increasingly less so. They reveal a wealth of information about the outward appearance of these animals, as well as their biology. The preserved scar was ringed in circular scales which were disruptive, compared to the overall patterning of the rest of the skin; this trend of disruptive scales forming around healing wounds can also be found in modern reptiles.

This beautifully preserved patch of scales reminds us that dinosaurs were no different than modern animals: hunters were not always successful, and prey was not defenseless. Oh, and the culprit behind the scar? Yeah, you guessed it - probably a Tyrannosaurus.

Rothschild, B. M., and Depalma, R. Skin pathology in the Cretaceous: Evidence for probable failed predation in a dinosaur, Cretaceous Research.

Tuesday, February 12, 2013

Darwin Day 2013

Charles Robert Darwin will forever be remembered as science’s greatest contributor. Without his theory of evolution via natural selection, not only would we understand pitifully little about the world around us, we would have no clue about our own origins, the evolution of life on earth, and the mechanisms which drive species to diversify and flourish in every condition possible.
The young Darwin. Despite his famous image as an older gentleman, he published most of his work in his younger years.
To me, he is more than just a great scientist. Darwin was a man who travelled the world, collecting scores of beetles, birds, and bones, finding something new and exciting with each little discovery. When something new arose, he did everything but overlook it. He was a true man of science, asking questions around every corner, never tiring until he reached a conclusion.

When he discovered the fossils of ground sloths in Patagonia, he didn’t dismiss them as remnants of a Great Deluge; he sought to discover not only what species the bones belonged to, but how such a creature could disappear from the face of the earth.  When faced with the mockingbirds, finches, and tortoises of the Galapagos Islands, he was driven by genuine curiosity to discover just how these species became so different from their sister species, despite being separated by mere stretches of water.
The way Darwin is most often remembered, as a snowy-bearded sage.
Even more amazing than his naturally scientific and curious mind was the fact that Darwin published his theory at all. He lived in an age when the church was an overbearing part of everyday life, and he was well aware that his theory would cause a commotion among Victorian society. Even closer to home, however, was the fact that his wife, Emma, was devoutly religious; Darwin’s dedication to the writing and publication of his theory caused a great strain on their relationship. And yet, despite all odds and opposition, not only did he publish his theory, but it was proven to be exactly right.

Today, more than ever, Darwin’s theories hold true. Even 204 years after his birth, he remains, unequivocally, the greatest mind to ever grace the scientific world. I end with a quote from Darwin himself which summarizes the beauty and wonder of the natural world through his own eyes.

…From so simple a beginning, endless forms most beautiful and most wonderful have been, and are being, evolved.”

Monday, February 11, 2013

Extinct animals got sleepy, too

Ever since Naish, Kosemen, and Conway's new book, All Yesterdays, was released, a slew of new and exciting reconstructions of extinct animals have been created. For those who don't know, All Yesterdays focuses on reimagining dinosaurs and other creatures of the past in ways we don't often picture them, while still retaining an element of realism. Examples include allosaurs and camptosaurs coexisting peacefully, plesiosaurs displaying carpetshark-like camouflage, and amorous stegosaurs forcing themselves upon unsuspecting sauropods.

One particularly cute interesting illustration features Tyrannosaurus rex, the famous king tyrant-lizard, curled up on the ground taking a paleo-nap. This is an activity not often featured by paleontographers: dinosaurs in the act of sleeping, settling down for rest, or waking up.

Tyrannosaurus rex taking a li'l snooze. Don't you just want to curl up with it on your sofa? Reconstruction by John Conway, from the book All Yesterdays.
I decided to take my own shot at depicting one of my favorite animals, Centrosaurus brinkmani, in a similar fashion. This old bull is just waking up, letting out a tremendous yawn from its heavily-ornamented head. The eye is supposed to be closed, but the wrinkles I added make it look like it's a bit open. That big red thing under its neck isn't gore or viscera; that's a dewlap.

Centrosaurus brinkmani waking up from a good night's rest. Despite its outward appearance, it was probably a lot less ornery when it woke up than I am.

Saturday, February 9, 2013

New ‘chid on the block

Azhdarchids are just plain weird animals. Theories on the lifestyles of these bizarre pterosaurs have ranged from depicting them as giant vultures, big shorebirds probing in sand and mud, and even as skimmers dragging their jaws along the water to catch fish. It wasn’t till 2008 that a reevaluation of the fossil evidence was conducted, and in a groundbreaking paper by Mark Witton and Darren Naish, it was determined that the azhdarchids had lifestyles similar to storks or ground-hornbills: they stalked their prey on dry land, walking and possibly even trotting or running along, using their huge heads and bills to subdue anything from amphibians to small dinosaurs. (Witton & Naish, 2008)
The newly-discovered azhdarchid, Eurazhdarcho. Reconstruction by yours truly.
This week, news of a new species of azdarchid from Romania was published. Eurazhdarcho langendorfensis had a wingspan of 3m (~10ft), and while it wasn’t the largest species (in fact, it is ranked among the smallest), it still would have been a sight to behold in the flesh. The discovery of any new species from this bizarre family of reptiles is significant, as most fossilized azhdarchids are known from very fragmentary remains. E. langendorensis, in fact, is one of the most complete specimens, yet it is only known from 15 individual bones.

Even more interesting than the (relative) completeness of E. langendorfensis is the environment in which it lived. At the time when Eurazhdarcho lived, Romania was an island in the Tethys Sea. As part of a great archipelago, it was one of numerous scattered islands which would one day form Europe. On this island, which was then covered in dry forests and seasonally swamped with monsoonal rain, Eurazhdarcho lived alongside a variety of dinosaurs. This was a continental, terrestrial environment rather than a coastal or oceanic one, further enforcing the hypothesis that azhdarchids were the “terrestrial stalkers” that Witton and Naish had proposed.(Vremir et. al, 2013) However, Eurazhdarcho wasn’t the only stalker on the island. There was something far, far bigger.
The monstrous Hatzegopteryx. Reconstruction by Mark Witton.
Hatzegopteryx thambema was a tremendous animal: as tall as a bull giraffe, it weighed up to 250kg (~550lb) and sported a 12m (~40ft) wingspan. Four times as large as Eurazhdarcho, H. thambema was likely the dominant predator of the island; with a massive, toothless beak, it likely ate just about everything it could swallow, from amphibians to small dinosaurs to foliage. Yet, while H. thambema grew to epic proportions which far dwarfed Eurazhdarcho, the two species were able to coexist.

Sympatry is when closely-related species, which differ in size, overlap in range but not in niche. This is a common occurrence in the modern world, and it comes as no surprise that it happened in the Mesozoic Era, but fossil evidence of this is uncommon. The fact that H. thambema and Eurazhdarcho overlap in range indicates an instance of prehistoric sympatry. The two avoided competition by simply feeding on different diets; the larger of the two species was adapted for a larger menu, while the smaller could exploit resources which the larger may overlook. This eliminates competition and allows the two species, no matter how different in size or similar in genetics, to both survive in the same habitat.
Evidence for sympatry in azhdarchids has been found in both North America and Europe. Image from Vremir et. al, 2013.
The remains of small azhdarchids are commonly found in the same formations as giants are. Perhaps, like herons or egrets, several species of azhdarchid inhabited the same environment and used the same generalist feeding strategy, separated only by size. Fossils not only have the ability of individual animals and species, they give us a clear picture of how these species interacted with one another. Each discovery we make, the Mesozoic world becomes a much more complex and beautiful one.


Vremir M, Kellner AWA, Naish D, Dyke GJ (2013) A New Azhdarchid Pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: Implications for Azhdarchid Diversity and Distribution. PLoS ONE 8(1): e54268. doi:10.1371/journal.pone.0054268

Witton MP, Naish D (2008) A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271

Wednesday, February 6, 2013

If it looks like a duck, etc., part II

Making a mountain of a mole-duck
While the turtle-jawed goose foraged the forests of Kauai during the day, nighttime on the island brought out an entirely different, and even weirder, character. Snuffling through the underbrush, poking its sensitive bill through the leaf litter, something else was stirring.

Enter Talpanas lippa, the nearly-blind mole-duck. The evolutionary origins of this bizarre bird are still a mystery and, like the turtle-jawed goose with which it existed, the greater age of Kauai had clearly wrought the mole-duck into a super-specialized and unique species. T. lippa was adapted not for a life of browsing or dabbling for water plants; instead, it probed the detritus for worms and insects like the kiwis of New Zealand.
Talpanas lippa, the nearly-blind mole-duck of Kauai. Reconstruction by Julian Hume.
The largest mole-ducks were the size of female mallards, though their physique was much stockier. Its legs were shorter and stronger than those of similarly-sized ducks, and its feet probably lacked webbing, as this was an animal clearly adapted for the terrestrial life. Though a complete skull remains undiscovered, the holotype fossil of this species is its braincase, revealing unique characteristics about the mole-duck beyond its external features.

The true weirdness of the mole-duck lies beyond its stout body. The foramina, holes through which nerves and arteries are connected to other areas around the skull, are unlike those found in any other living species of duck. The optic foramen, connecting the brain to the optic nerves, is extremely reduced, and leads to equally small orbits: T. lippa had beady eyes and extremely poor eyesight. (James et. al, 2009)Now, these adaptations are common among nocturnal insectivores, and they do not pose a problem to the little mole-duck. But every nocturnal hunter needs a way to find its prey; if it didn’t rely on eyesight, just how did it seek out its food?

The mole-duck, rather than using sight to find its prey, used its sense of touch. Kiwis use whisker-like feathers to feel for worms in the soil, but the mole-duck had a much broader, flatter bill. Connected to this bill, however, were huge foramina through which passed the bird’s trigeminal nerves, which are responsible for sensation in the facial region. The mole-duck, it seems, had an extremely sensitive bill, perfect for detecting minute vibrations and movements under the rotting leaves and logs on the forest floors of Kauai. (James et. al, 2009) Platypuses (platypi?) hunt their aquatic prey in a similar fashion: their bills are extremely sensitive, and can be used like a giant, flat hand as they sift through the substrate.

It doesn’t get much weirder than T. lippa. It really doesn’t. Over generations and generations, the awesome powers of evolution turned an ordinary-looking duck to a stumpy, nocturnal, platypus-billed, nearly-blind insect-hunter. It’s a shame that such an interesting and indescribably unique species no longer scuffles through the nighttime Hawaiian forests, where daylight saw the march of heavyset, turtle-jawed, titanic herbivorous waterfowl. The more we discover about the bizarre ducks of Hawaii, the more we learn about the incredible niches which these waterfowl were so diverse to fill.

Cooper, A.; Fleischer, R.C.; James, H.F.; Olson, S.L.; Paxinos, E.E.; Quinn, T.W.; and Sorenson, M.D. 1999. Relationships of the extinct moa-nalos, flightless Hawaiian waterfowl, based on ancient DNA. Proceedings of the Royal Society B 266, 2187-2193.

James, H.F. and Olson, S.L. 1991. Descriptions of thirty-two new species of birds from the Hawaiian Islands, part I. non-passeriformes. Ornithological Monographs 45, 1-88.

James, H.F.; Olson, S.L.; and Iwaniuk, A.N. 2009. Extraordinary cranial specialization in a new genus of extinct duck (Aves: Anseriformes) from Kauai, Hawaiian Islands. Zootaxa 2296, 47-67.

Tuesday, February 5, 2013

The feathered dinosaur that didn't force anyone to rethink anything about bird evolution

Eosinopteryx brevipenna is a newly-discovered troodontid from the northeast of China. This little animal has been causing quite a stir among news outlets and paleontological communities, as it has been touted as the force behind a new way of thinking of the evolution of birds and flight. While the discovery of this creature is of course an exciting one, I believe that its impacts on our understanding of avian evolution have been largely overstated by various media.

E. brevipenna lived 150Ma in what were once swamp-like subtropical forests, and coexisted with many diverse and interesting species, from quill-backed heterodontosaurs to bat-like pterosaurs. Two of its close relatives also shared this environment; together, these three species have shed much information on the evolution of birdlike traits (including flight), as well as on adaptive radiation.

Anchiornis huxleyi, a troodontid closely related to Eosinopteryx brevipenna. The colors in this reconstruction are consistent with the fossilized feathers of this species.
Let’s travel all the way back to 2009, when the fossil of a curious Chinese troodontid was described. This was Anchiornis huxleyi, an extremely birdlike species which was the first Mesozoic dinosaur to have its color officially determined. Apart from woodpecker-like coloration, A. huxleyi displayed a number of other avian features, including long forearms which bore flight feathers (though these were not as aerodynamic as gliding microraptorines or true birds) and a highly mobile wrist. Troodontids such as A. huxleyi did not give rise to true birds, yet they displayed traits remarkably similar to them. This fact spurred a reevaluation of the relationship between non-avian and avian dinosaurs, and led to many questions about just where to draw the line between dinosaur and bird, or if this was even possible anymore.

Yeah, yeah, the same reconstruction of Xiaotingia zhengi used in every article about the species. Reconstruction by Xing Lida and Liu Yi.
From the same time and place as E. brevipenna (which I promise I’ll get back to writing about in a second) and A. huxleyi came Xiaotingia zhengi, a species remarkably similar to the famous Archaeopteryx lithographica, often considered the first bird. In fact, the two were very closely related, and therein lay the problem. The discovery of X. zhengi led to game-changing questions:  was this the new first bird? Could A. lithographica even be considered a “bird” anymore, if X. zhengi was to be classified as a non-avian dinosaur? If not, where do both species fit in the evolutionary history of deinonychosaurs and birds? (Xu et. al, 2011)

Since then, many new feathered species have been discovered, and each one is reported to have earth-shaking effects on the taxonomy of non-avian and avian, and how the two are related. The exact position of these species in the sprawling cladograms of deinonychosaurs becomes more and more refined with each related fossil found. The most recent analyses of these fossils place the aforementioned animals within Deinonychosauria, the clade which includes dromaeosaurids and troodontids, and those species helped further refine our understanding of this complex evolutionary history and reach the current conclusion.

So, back to my main topic. Finally, right? Anyway…

E. brevipenna has been portrayed by several media outlets as “forcing” paleontologists to reevaluate the evolution of birds, flight, and feathers. In honesty, E. brevipenna, while it is an interesting and unique species, does less to shed light on bird evolution than A. huxleyi and X. zhengi did.

The only specimen of E. brevipenna. The avian features of this troodontid, such as feathers and a mobile wrist, can clearly be seen in this beautiful fossil.
The almost completely-preserved fossil of E. brevipenna shows an animal very similar to A. huxleyi. The two were, in fact, sister species; they occupied the same habitat at the same time and were incredibly closely related, yet they were extremely different. While A. huxleyi was adapted for a life in the trees, where it could climb and glide from tree to tree in pursuit of prey, E. brevipenna had short feathers on its arms, legs, and tail. Not only were the feathers shorter, but compared to those of its arboreal relative, they were much simpler and would not have provided support for flight even if they were longer. Even the skeletal anatomy of the shoulders and arms of E. brevipenna prohibit the ability of the wings to flap. (Godefroit et. al, 2013)

These traits point to one way of life for our new little troodontid: it was a ground-dweller. Ground-dwelling feathered dinosaurs are by no means rare; the majority of feathered non-avian dinosaurs discovered so far are ground-dwelling. However, E. brevipenna evolved from ancestors with the power of flight, or at least the ability to glide. Its shortened feathers and stiff arms allowed it to be a cursorial animal, pursuing prey on the ground, while the closely-related A. huxleyi remained in the trees.

E. brevipenna: the proud ground-dweller surveying its domain. Reconstruction by Emily Willoughby.
This phenomenon, when closely-related species evolve to fill different niches, is an example of the classic concept of adaptive radiation. The most notable example of adaptive radiation can be seen in the different beak sizes of mockingbirds in the Galapagos, and our fossilized example portrays a similar scenario: the two species at hand evolved to exploit completely different food sources.

While E. brevipenna is a remarkable species which reveals a great deal of new information on the evolution and ecology of small-bodied theropods, it does not have the profound effect on the evolutionary history of birds or feathers as so many sources claim. It did not shake the very roots of the study of feather evolution. However, it does provide yet another example of the diversity of feathers in the Mesozoic Era, a time when many more varieties of feathers were found on a wider range of species, helping each one fill a different niche in a different environment. The discovery of this novel little animal cannot be overlooked, though it needs to be looked at for its true value as an example of adaptive radiation in an extinct family.

Claeys, P.; Demuynk, H.; Dyke, G.; Escuillie, F.; Godefroit, P.; and Hu, D. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications. doi:10.1038/ncomms2389

Du, K.; Han, F.; Xu, X.; and You, H. 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature. doi:10.1038/nature10288

Saturday, February 2, 2013

If it looks like a duck and flies like a duck, it’s definitely not a subfossil Hawaiian duck

It’s pretty hard to find a body of water without finding ducks. They’re found on every continent except for Antarctica, and have made their way to a number of oceanic islands. This, of course, has led to the evolution of some downright daffy species.

Compared to common barnyard ducks, the extinct ducks of Hawaii were short-beaked, pot-bellied, and even less graceful. They were Hawaii’s own version of another famous flightless island-dweller, the dodo: descended from ancestors who could fly, they evolved to fill the niche as the island’s main herbivores. Unfortunately, the fate of Hawaii’s ducks followed that of the dodo. Shortly after the arrival of humans, these wonderfully bizarre birds vanished from their island paradise.

Moa-nalos: the turtle-jawed and stumbling pot-bellied ducks
The biggest of the Hawaiian ducks were the moa-nalos, a name formed from the Hawaiian words moa (“fowl”) and nalo (“lost”). (James & Olson, 1991)The word moa will appear familiar to those interested in extinct island birds, as the huge ratites of New Zealand shared this name. And, like the moas of New Zealand, these birds were equipped for a life on the ground.
Various species of Hawaiian ducks and geese, both extinct and extant. Top row, left to right: greater Hawaiian goose Branta sp. (extinct), Thambetochen chauliodous (extinct), T. xanion (extinct). Bottom row, left to right: Chelychelynechen quassus (extinct), greater Hawaiian goose B. hylobadistes (extinct), Ptaiochen pau (extinct). In the center is the nene B. sandvicensis the only surviving species of this group. Artwork by Julian Hume.
The moa-nalos displayed extremely robust legs and hips, as well as wings and keels reduced beyond use. With the exception of one species, moa-nalos also sported large, tooth-like ridges in their bills, perfect for grinding vegetation. All species probably lacked webbing on their feet, allowing them to lead a life on land with greater ease. Four species, consisting of three genera, have been discovered thus far.

The nearly-unpronounceable Chelychelynechen quassus, found on Kauai, translates to “broken turtle-jawed goose,” in reference to its extremely shortened bill and the locality of the original fossils: in the middle of a jeep trail. The remains were found in a shattered state due to the passing of cars overhead. C. quassus is the aforementioned token species which lacks the toothy ridges present in other species. This is likely due to the age of Kauai: older than the other Hawaiian islands, C. quassus had more time to adapt to a strictly herbivorous diet. Perhaps, had the other species endured, they would have developed similar adaptations.
C. quassus, the turtle-jawed goose of Kauai. Reconstruction by Carl Buell.
The two species of Thambetochen are surprisingly similar given their geographic distribution. Although they are found on two entirely difference islands, the distinction between the two species appears to be in general size. T. chauliodous is the larger of the two species, and also possesses a shorter, more curved bill than T. xanion of Oahu; the latter species also displays prominent comb-like ridges in its bill. Though T. chauliodous was present on both Maui and Molokai, there is no obvious variation between the two populations.

T. chauliodous shared the island of Maui with the unfortunately-named “stumbling goose,” Ptaiochen pau. P. pau was named for “the propensity of the species to fall into holes,” a reference to the environment in which the fossils were found, mostly in caves and valleys. The remains of P. pau are much more common at higher elevations than those of T. chauliodous; likewise, T. chauliodous is more common in the lowlands. This difference in range, even on the same small island, explains how the two species were able to avoid competition. (James & Olson, 1991)*
P. pau, a denizen of the highland rainforests of Maui. The toothlike ridges which allowed the moa-nalos to process tough plant matter can clearly be seen in the bills of these two birds. Reconstruction by Julian Hume.
DNA analysis of the moa-nalos indicates that, despite their goose-like appearance, they evolved from the same common ancestor as the most common family of ducks, the dabblers. (Cooper et. al, 1999) These include recognizable species such as mallards and wood ducks. Despite the weirdness of the “lost fowl,” there was one Hawaiian duck even stranger still.

*The vast majority of the information in this section comes from this text. It provides fantastic detail, comments, and visuals about the moa-nalos and many more extinct Hawaiian species. The references to this text are too numerous for me to add without being a nuisance. Hence, this footnote.

Check back soon for the jaw-dropping, hair-raising second part of this post.