Special Bird

(C) Lia Booysen

As everyone the world over celebrates the New Year (in the Julian calendar anyway), a few people want to see some things about Aepyornis. I think that David Attenborough and the BBC have taken care of how popular this bird is. If that was not enough to prove its popularity, look at the admiration still held by the people of Madagascar for the giant birds. World mythology sometimes attributes the myth of the Roc, a giant bird of prey, to the eggs of Aepyornis as well as the idea that it may have only been a baby for an even larger bird; ratites remain quite juvenile in appearance in many ways. These birds even provided inspiration for an H. G. Wells short story: Aepyornis Island. Please read the short story and enjoy the interpretative artwork from Lia Booysen related to the story. Their appearance in video games, while not entirely novel, also attests to their popularity. I certainly like the look of these birds in Zoo Tycoon 2 myself, though subsequent public modifications have made them appear less "majestic".

Extinction Hypotheses

Happy Madagascan children with an Aepyornis egg, (C) Madagascar-tribune

There are many hypotheses as to how Aepyornis went extinct. Many of those hypotheses center on human interaction because post-settlement by what we would now consider the indigenous people (those are the Malagasy people, a healthy melting pot of groups from places like Borneo and southeastern Africa). Considering that Madagascar was the last large landmass on the planet to be settled by humans, the wildlife had a very good long run of evolving with little to no human disturbance; evidence exists for foraging groups spending short periods of time on the island prior to permanent settlement. The question with Aepyornis becomes what kind of human interaction could have caused a 400 kg bird to go extinct? Hunting seems to be a natural answer to that question, but the bird was so enormous that a sustained "farming" of the bird would have been able to feed the population of the entire island quite well for an extended period without causing the extinction of the birds. This may have been the neither goal of the population nor within their scope of worry. However, consider the implications of a "farmable" 400 kg bird and how that might change holiday dinners! Another possibility was the hunting of the young or unborn birds. Due to their size it is unlikely that Aepyornis ever laid large clutches of eggs; extant ratites are capable of laying a small amount of eggs in each breeding season but are considerably smaller. As each egg was large enough to feed multiple people it is feasible to assume that they were taken entire nests at a time, allowing for either multiple meals or a village sized egg feast. Assuming communal nesting sites, the breeding season for these birds alone could have sustained the island and more. This path to extinction is straightforward of course; the ingestion of one's offspring eventually leads to the downfall of one's population and subsequent eradication of the species over time. The third hypothesis is concerned with a combination of the other two hypotheses coupled with habitat loss as a major factor in the extinction of the birds.

Papers for Eggs

Aepyornis papers, as with many aspects of the history that has been documented about these birds, are mostly about eggs. Constituting the most readily available fossil evidence of the birds, these eggs are easily studied because of their abundance. Not all of these egg papers are really about the eggs though. They have to be more specific than many studies because studies that simply describe eggs only really need to be done once. However, describing the calcite orientation in one study and isotope chemistry of the shell in another. Despite a lesser abundance of skeletal remains studies of estimated weight have been published as well. A combination of studying the eggs and the skeleton of Aepyornis culminated, at least once, in a great study of the osteology of embryos that were preserved with eggs. Because we have embryos as well as adults we have a strong line of ontogenetic evidence concerning the bird. Having a great deal of studies from egg to adult is great for any extinct animal and we are extremely lucky to have this much for this animal.

Young Attenborough

Yesterday's BBC television clips were, when put together, a great short documentary definitely worthy of movie Monday. Instead of searching for a great deal of new documentaries, and there are not all that many that exist, I have decided to share a pair of videos that show just how much David Attenborough loves Aepyornis. There are many reasons that Attenborough has discussed this bird in documentaries decades apart, but he really must have some love for the birds as it has been reported that he kept one of those fossil eggs he had rebuilt while in Madagascar and, as far as the story goes, still has it some 54 years later. In the Zoo Quest to Madagascar show that these come from he also searches for lemurs and other Madagascan animals. However, the important thing is that David Attenborough discusses an egg and shows just how large those eggs were. Also of note is the fact that locals know of egg fragments despite the birds being extinct for a significant amount of time.

Average Facts, Giant Bird

Elephant Birds appear to be quite popular on the internet. About, Encyclopedia Brittanica, and the BBC all weigh in concisely and with some good images of the bird in question. Many other independent sites also have fact sheets, paragraphs, and even short but detailed descriptions of Aepyornis. The real wealth of Elephant Bird information may be in the short clips below:

On the disappearance of Aepyornis:

On the height of Aepyornis:

On the egg of Aepyornis:

On the extinction of Aepyornis:

Forgetting Feathers

Image courtesy of Museon; Den Haag, Nederland

Instead of looking at different feather patterns in different illustrations of Aepyornis the art for Saturday focuses much more on the morphological characteristics of the Elephant Birds. A bird weighing as much as a Polar Bear is an interesting animal no matter what shape it may be presented in. However, Aepyornis is shaped in a very familiar way to other large terrestrial birds; not surprisingly Aepyornis looks very much like other ratites, especially ostriches. Like ostriches, Elephant Birds possess large feet that are mostly held flat on the ground and atrophied wings. The wings are not entirely absent from the giant birds, but at almost 3 m (10 ft) tall, the wings would not be of much use in getting off the ground unless they were significantly larger than they are. The large feet compensate by providing significant thrust and allowing the bird to move briskly along the ground. Aepyornis possessed legs far too robust to be as gracile as other ratites and an ostrich or an emu could easily outpace the large bird despite having slightly shorter legs. Instead, the Elephant Bird was much more likely to use its legs like those of cassowaries; kicking another animal with force and standing their ground would be more likely occurrences than outrunning predators. A 3 m bird would not have many predators, especially on Madagascar, once full grown. However, like most ratites, it also would not likely have been a predator, even though it could have easily been an apex predator on Madagascar. There were other birds that may have taken on that duty in their stead.

Christmas Dinner

I skipped yesterday's post because we know most of the reasons that Gastornis is popular and it felt as though it was a post that did not need to be made. Regardless, Happy Christmas (if that is your thing) and Happy Holidays of various other sorts that exist.

This week will be the final fossil bird week to close out the year. I had contemplated discussing one of the oldest extant species of birds, the Magpie Goose (Anseranas semipalmata), but decided to be entirely fossil oriented to close out the bird topic. The fossil bird this week is the genus Aepyornis, a group of extinct ratites endemic to Madagascar. Known colloquially as Elephant Birds, the genus consisted of four species (A. gracilis Monnier 1913; A. hildebrandti Burckhardt 1893; A. maximus I. Geoffroy Saint-Hilaire 1851; and A. medius Milne-Edwards and Grandidier 1866) and is touted as the heaviest group of birds to have ever lived. The largest, A. maximus, is known to have weighed up to 400 kg (880 lbs). This is a known number because Elephant Birds have only been extinct for approximately 1000 years. Being a ratite, and weighing 400 kg, Aepyornis species were not capable of flight, no matter how much they may have wanted to escape Madagascar. Ratites tend to look vaguely like chicks throughout ontogeny, and such "youthful" appearances may have caused early explorers to assume that Aepyornis was not fully grown, even at 400 kilograms. However, use of the name Elephant Bird by many, including Marco Polo, may have actually referenced raptors living on or near Madagascar more than the giant ratites. Despite a confused nomenclature, Elephant Birds are enormous recently extinct ratites, like Moas, that went extinct partially because of human interaction (i.e. hunting). Considering an Aepyornis egg was large enough to feed a small family hunting the animals to extinction does not seem very far-fetched at all.

Left to right: Aepyornis maximus, Struthio camelus, Homo sapiens

More Anatomy

Compiled by Adam Pritchard and Matt Borths of the Past Time podcast

This week we have discussed the legs, feeding apparatus and likely diet, and general familial history of Gastornis. One of the only other anatomical features we have not discussed in detail are the wings of this animal I noted before that the wings appear to be more developed than those of the true terror birds. This lends itself to a more well developed keeled sternum that is often associated with flight muscles. These muscles appear to be weakly developed in Gastornis; however, their existence and the development of the keeled sternum, regardless of how slight that keeling is, allow some insight into the evolutionary position of Gastornis in Anseriformes in relation to the capability of flight within the family. There is a reason that ducks and geese are high fat, heavily muscled birds; that in turn has led to their inclusion in our diet. Ducks and geese have low aspect wing ratios and less than desirable aerodynamically shaped bodies. They tend to be a little rotund, but most herbivorous animals are as they require more gut to process vegetation. Gastornis was also probably a fairly rotund bird as it would have also required significantly more digestive tract than the carnivorous contemporary birds around them. Gastornis was not flying though, so the fact that its family tree members have a lot of muscle to power themselves through the air definitely influenced its keeled sternum and possibly causing Gastornis to also have enormous muscles in the chest. One conclusion we can draw from this is that Anseriformes were flying both before and after the terrestrially confined Gastornis was running around the forests of the northern hemisphere.

Use It To Crunch Seeds

Evidence has mounted that Gastornis was not a carnivore a great deal since it was originally covered in this blog. Back in 2012 when we originally discussed the diet of the giant bird and share all kinds of illustrations and clips from the Walking With series, meat was the only thing considered to be on the menu for Gastornis. Since that time biomechanical studies from earlier have been countered by evidence from chemical analyses that show that the diets of these birds were most likely highlighted by vegetable matter. When we look at the beak both possibilities obviously make sense. The Witmer and Rose biomechanical study asserted that the beak was strong enough to break bones and certainly to kill small animals like Eohippus. They are not incorrect and the implications that they made regarding diet are logical, especially for a bird that appears to be extremely convergent with South American terror birds. However, that power could have also been used to break open tough seeds and their meat inside. The large beak appears to have been mostly flattened in the oral cavity (the roof of the oral cavity or the ventral shelf of the premaxilla and maxilla), which is good for crushing, but not entirely ideal for breaking seeds open in the most efficient manner. What could be more efficient for this purpose may be considered coincidental or may have been lost in fossilization. The anatomical character that we are considering here could be a ridge or sharp edge to the beak that was keratinized for added strength. Assuming that this was not lost and may not have existed (I have not seen the fossils first hand and cannot therefore assert to its existence or loss) another option to make the breaking open of seeds more efficient, is occlusion of the upper beak that we have discussed many times with the lower beak or mandible (dentary, splenial, angular, and surangular). This occlusion can be seen, but is minimal between the beak and mandibles. It can be assumed from these bones that the keratin ramphotheca covering the beak would not have occluded differently, but we cannot say that they did not have sharp edges capable of shearing seeds. Given all of the papers and anatomical evidence, it seems that we could consider Gastornis more of a terror to seeds, than other animals.

The Proposed Diet

Many reasons exist as to why the giant Anseriform Gastornis is hypothesized to have eaten many little horses daily, or weekly. Chief among these reasons is, of course, that the enormous solid and akinetic bill of Gastornis was a perfectly suitable weapon for concussing or otherwise subduing the earliest forms of horses. When we say early horses or small horses we are talking about the dog-sized (think somewhere between beagle and cocker spaniel if that helps) Eohippus that was still able to navigate the forests and enclosed areas of the Eocene. Later horses could not manage forests as well due to their larger sizes. Eohippus was still hypothesized to have a small amount, at least, of speed associated with its locomotion. Gastornis' slower speed led to the hypothesis that the giant bird was an ambush predator, surprising the small horses and using its solid beak as a sledgehammer to know the horses down and disabling them. There are representations of this all over the internet. The most notable and memorable is probably the one that the most people have seen. View the hunt below and bear in mind that this is a reasonable hypothesis for this bill, but there may be another viable hypothesis which we will attempt to explore tomorrow, granted that there are enough papers to discuss diet well. The strangest thing about this video is actually that the killing stroke has been edited out a bit.

Giant Facts, Giant Bird

The revelation from yesterday that Gastornis is an enormous duck should have sunk in quite well by now. If it has not, here are some interesting facts about that giant duck. The first fact pages come from the BBC which chose Gastornis as a key figure in the Walking With Prehistoric Beasts series that appeared after the dinosaur series. That version of Gastornis was well done; however, they did imply that the hatchet-like movement of the beak was basically the same mechanism used by other large birds that lived, rather than noting the lack of a known hook on the premaxilla. The page hosted by Dinosaur Jungle does not worry about this hook-and-hatchet conundrum and instead simply discusses the facts that are know about Gastornis. Intriguingly, the image used on the page makes Gastornis look much more like a giant walking eagle and a great deal less like a duck relative; we do not expect it to look like a duck exactly, despite how much we have mentioned that it is related to ducks and geese. Of perhaps the most interest today, is an entry in Brian Switek's National Geographic blog Laelaps which introduces the idea that the bill of Gastornis was constructed for a more herbivorous diet than a fleshy diet. I must highly recommend reading this as an introduction to the topic of diet that we will discuss in the next couple of days. The last time Gastornis appeared in this blog we accepted the predatory role, and it was mentioned heavily in yesterday's entry also, but we will explore other uses of the morphology of the bill that we have been very actively discussing this weekend so far.

Well Known Birds

Gastornis with Titanis inset

The terror birds of the northern hemisphere are not all terror birds in their own right. The term terror bird is usually used in reference to the group of birds belonging to the family Phorusrhacidae, to which Gastornis does not belong. The family of Gastornis is actually Gastornithidae, but the order is Anseriformes, meaning that Gastornis is in fact a giant duck (or goose if you like those better). The order of the true terror birds is Cariamiformes, a group that includes the extant Seriemas; predatory South American terrestrial birds much like the African Secretary Bird. What all of this means is that the lineage of Gastornis evolved to look, act, and dominate its landscape convergently rather than as an offshoot genus of the true terror birds. This convergent evolution is seen throughout the anatomy of the bird (the fossil anatomy that we can look at that is of course). The true terror birds, represented by Titanis, have a hooked, stout bill consisting of the premaxilla and maxilla. The bill is highly akinetic and was likely used as a hatchet-like weapon in prey acquisition. The bills of Gastornis were also highly akinetic and composed of the premaxilla and maxilla. However, they lack the premaxillary hook seen in terror birds and, while they may have also been used as a hatchet-like weapon, the lack of a hook means that the bill could not be used to pierce prey. Instead the bill would have acted more as a hammer, bludgeoning prey. The synsacrum (fused sacral and sometimes lumbar vertebrae) of Gastornis was longer than that of the Titanis; however, this does not mean that Gastornis was more agile or that it used this elongated tail to run with better balance. The legs of Gastornis are actually more robust and less likely to have allowed for bursts of speed than the agile but powerful lower limbs of Titanis. These traits lead to the hypothesis that Gastornis may have been an ambush predator rather than an actively stalking and chasing predator. Gastornis also possessed traits that are reminiscent of their closest relatives in that it had fully formed, but reduced and weakened, wings and a sternum that was mostly flat. An extremely reduced ridge is somewhat present in the midline that is homologous to the fully keeled sternum of flying Anseriformes. Titanis and other Phorusrhacids have an absent keeling of the sternum or a completely flat (rounded as encloses the thorax) sternum.

Previously Viewed Gaston's Bird

From a paper by Matthew, W. D.,  Granger, W.,and
Stein, W. 1917.

Once in the not too recent past we discussed what is basically a giant terror turkey of the northern hemisphere. Discovered in Europe and described under the name Gastornis by Hebert at the same time (a pair of decades later) as it was discovered in North America and described as Diatryma by E. D. Cope and Barornis by O. C. Marsh. Diatryma and Barornis, being named 21 and 49 years after Gastornis respectively, have fallen to the level of junior synonym. However, regardless of the level at which these particular species may reside in hierarchical taxonomy, the discovery of multiple members of the genus on multiple continents is of great importance to understanding how "in charge" birds were in the early Cenozoic. Enormous birds were clearly the apex predators of South America, and likely much of Australasia as well with potential large predatory birds spreading to Africa as well. Gastornis is known only from Europe, Asia, and North America, but the fact that apex predators in northern and southern hemispheres both were avian is astounding. Gastornis consists of 3 - 4 species from Europe (G. parisiensis Hébert, 1855;G. sarasini Schaub, 1929;G. geiselensis Fischer, 1978; and G. russeli Martin 1992), a minimally known Chinese species (G. xichuanensis Hou, 1980), and the extremely (comparatively) well known North American species (G. gigantea Cope, 1876).

Sometimes It Is

Popularity because of popularity sounds funny, but it is a theme that has been addressed here many times before. Perhaps too many time in fact. The fact with fossil animals, though, is that sometimes they are famous just for being famous. The penguins discussed this week fall into that exact category as nothing makes them exceptionally famous except that they are well known for being giant fossil penguins. To anatomists and ornithologists they are amazing specimens of the early radiation and specialization of the penguin family. They are testaments to the anatomical organization of penguins in that they provide us with a first indication of anatomy that is still readily employed by extant penguins; adaptations that have changed little in 36 million years are obviously well situated to working in the role and environments in which they are employed. Regardless of how they are touted, both of these animals were indeed kings of the water in their day, in the bird world. They remain important and amazing in our view today.

Fossil Collections

Icadyptes montage. A) Icadyptes and a Humboldt penguin (D. Ksepka);
B) Wings of (L-R) Short-tailed Shearwater, Waimanu, Icadyptes, Emperor Penguin
(Ksepka and  Ando 2011); C) Illustrator's interpretation of Icadyptes

The collected fossils of both Inkayacu and Icadyptes are fairly similar, as we would expect with contemporaneous and similarly sized penguins. What exists, however, to tell them apart from one another? The answer, as in any fossil animal, is in the bones. No one knows these fossil penguins better than Daniel Ksepka, now with the Bruce Museum in Greenwich, CT and it is thanks to his tireless study and description of both taxa that we know the key characters of each animal. He had help now and again and the description of Inkayacu was spearheaded by the University of Texas, overall, but much of what has been written about penguins in the past decade or so has been written by Ksepka and his collaborators. In the case of Inkayacu some of the evidence of difference from Icadyptes is actually found in the feathers of the animal. The precise imprints that were made in both the matrix material around the bones is so well preserved that the shapes and sizes of the pigment containing melanosomes has been preserved as well as the shape and size of the contour feathers that covered the body below the flight feathers. An important note of distinction ought to be mentioned here for the less avian-inclined. Despite not flying in the traditional sense, the feathers of the wing that are used in locomotion in penguins are considered flight feathers as they still perform the same role and the style of swimming of penguins is very much like a submarine flight. What is very interesting about the bones of Icadyptes shown here is their fairly obvious resemblance to those of other fossil penguins (Waimanu tuatahi) and extant penguins here represented by an Emperor Penguin (Aptenodytes forsteri). The flipper of Inkayacu is absent some elements, but it also very close in resemblance to extant and other fossil penguins. The skulls are morphologically similar as well, but the flippers are more important in showing that penguins were highly specialized as long ago as these 36 million year old animals. The skull shape had developed multiple times in other waterbirds, making their convergent shape less important for defining what makes a penguin.

From Clarke, et al. 2008

References:

• 1.- Clarke JA, et al. 2007. Paleogene equatorial penguins challenge the proposed relationship between biogeography, diversity, and Cenozoic climate change. PNAS 104 (28): 11545-11550.

• 2.- Clarke JA, et al. 2010. Fossil Evidence for Evolution of the Shape and Color of Penguin Feathers. Science 330 (6006): 954-957. 

• 3.- Ksepka DT and Ando T. 2011. Penguins Past, Present, and Future: Trends in the Evolution of the Sphenisciformes; del libro “Living Dinosaurs: The Evolutionary History of Modern Birds”, editorial John Wiley & Sons.

Black and White Print, Not Feathers

The most important thing to remember about these fossil penguins is that they are very much like modern penguins. That fact born in mind, reading the papers detailing studies of these penguins makes the papers easier to feel okay about. Not understanding that these penguins are like modern penguins in many regards make the papers seem very odd, as they discuss the animals in ways that make them seem quite modern in respect to the "oddness" of other fossil animals in comparison to their extant descendants. After reading the papers this logic makes sense, I promise. Those papers detail the evolutionary history of penguins as well as detailing individual aspects of both penguins. Those include osteology and the colors of feathers. Fossil feathers and coloration is a fantastic topic actually, and I definitely recommend reading that last paper on Inkayacu.

From Clarke, et al. 2010.

Penguins in History

Yesterday I shared videos for both Inkayacu and Icadyptes. Somehow, despite the fact that penguins are probably the neatest flightless birds, there are not more stories and videos devoted to these two ancient penguins. It is both sad and great that we do not really need a video concerning these two penguins directly to know how they fed, their mode of locomotion, or what they looked like. The two penguins were both penguin-like in appearance and most likely swam the same way that extant modern penguins swim. The feeding done while swimming, of course, was probably also similar if not identical. The depth at which that feeding was done in each genus was probably much different though. Due to the fact that extant penguins provide a good hypothetical proxy for these fossil penguins, please enjoy this wonderful ballet of penguins swimming, doing dopey things, and generally being penguins.

Penguin Facts

Sharing facts for two animals today is best done in a list format. Therefore, please attend to the following lists!

Inkayacu:
About: http://dinosaurs.about.com/od/prehistoricbirds/p/Inkayacu.htm
Interview with Dr. Julia Clarke:

Icadyptes:
About: http://dinosaurs.about.com/od/prehistoricbirds/p/giant-penguin.htm
Animal A Day: http://animaladay.blogspot.com/2012/11/icadyptes-salasi.html

Dr. Rodolfo Salas showing fossils and an interview with Dr. Mario Urbina:

Penguins Competing for Space

Icadyptes; (C) Nobu Tamura

The two fossil penguins Inkayacu and Icadyptes were actually quite different despite living in similar areas and having similar ecologies.The pigments of the feathers of the penguins have been identified, tentatively but with few caveats, and this allows us to differentiate between the animals when feather impressions and melanosomes are present to identify the colors of the feathers. Icadyptes is similar to extant king and emperor penguins as far as we can tell in plumage. They appear to have had a few areas of yellow and black feathering but were mostly covered in white feathers Darker back feathers make deeper diving a realistic ecological impact on the way of life of Icadyptes. The darker black would allow for the penguins to be camouflaged from above when at deeper depths and their white feathers would have added to their camouflage from below as they would have blended in better with the lighter water nearer the surface. Drawing these conclusions we can say that it is likely that Icadyptes dove deeper than Inkayacu to feed. Sharks and contemporary mammals (I cannot seem to find an evolutionary appearance of Leopard Seals, but we can assume that they would have loved giant penguins given how much they love extant penguins) of the deeper waters would have preyed upon the penguins, making that camouflage necessary. Inkayacu, on the other hand, has been hypothesized to have been a brown to rusty red color below and black or a dark grey above. Again, the black or dark grey color would camouflage the penguins against the deeper waters, but the rusty color would not provide much camouflage against many backdrops. This line of evidence is used to argue that Inkayacu

Unattributed

is a shallow swimming penguin; there are melanosome related reasons as to why this is a possibility, but we can leave these at rest for the time being. At the moment, simply appreciate that there are two colorations hypothesized for the two penguins and that each color scheme denotes attributes of each species. The two disparate ecological niches would mean that the two penguins could live in the same area and feed on different prey without destroying the food sources of one another. It is an interesting system with two interesting and differently colored taxa represented.

Dueling Penguins

Icadyptes (top) and Inkayacu (bottom)

I have decided this week that we really need to look at two animals at the same time. Distinctly different but interesting and similar, the two giant penguins of South America, Icadyptes salasi and Inkayacu paracasensis were both approximately 1.5 m (5 ft) tall and were amazingly developed 36 million years ago such that they resemble modern penguins in shape and function from their bills to their feathers. The fact that they were enormous and built for swimming, like their descendants, means that the ocean ballet we see with the much smaller modern penguins was happening 36 million years ago with birds as tall as an adult human (using myself as scale because I am short). As now, these penguins ate fish while they darted about in the ocean and, with their larger bodies and heads, were definitely capable of grabbing larger fish than current penguins. Assuming that fish were also somewhat larger in their time that is. We know that even now some adult fish can reach astounding size, but do not always because of commercial fishing. Human over-fishing did not cause the demise of these penguins, however. Due to the fact that the two penguins were discovered in Late Eocene rocks of Peru, they must have been contemporaries and should be considered together to discuss the ecology of each as they would have interacted in life.

How Does One Become Famous?

The greatest toys I have seen (toys always relate to popularity in, I am sure, some mathematical way) of Jeholornis are actually quite interesting in their own right. These range from stuffed animals (see below) to styrofoam flyers to full on sculpture. I have to admit that the sculpture is amazing. There is a great deal of painstaking detail in that piece and I am quite impressed with it; I would own it if I could and I had a place for it. Jeholornis has occupied our imaginations and entertained our fancies about the origin of birds, and that is probably, in part, why it is such a popular early bird. The fact that it is an early bird has a lot to do with its popularity in the realm of paleontology. There is even a book (dedicated to all Jehol fossils really) that deals extensively with little dino-bird. It may be worth picking up, but as with any scientific book, it is difficult to find for a reasonable price.

Forgotten Yesterday

(C) Matt Martyniuk

I lost track of time yesterday and have to backdate this post. That is all well and good though on the internet. The first anatomical thing worth mentioning about Jeholornis is the long tail. The tail of this small bird is very dinosaur-like in its anatomy. It is a long slender tail that appears to have been covered in small(ish) feathers down the length of the appendage. The end of the tail is covered in fan shaped brush like set of retrices that look something like a cat-tail (the plant not the mammal) in silhouette. Long tails like this are not unheard of in the bird world as birds such as magpies often have long tails that are as much for display as they are for controlling flight. Perhaps the reason for this long tail was for display, but it could have also been used to steer an otherwise somewhat unwieldy bird through the air during powered flight. Barring that, and assuming that Jeholornis was a good flyer, it may be the simplest explanation and the tail may have been for display purposes only.

The claws on the wings of Jeholornis are also of great interest. One of the age old questions surrounding birds is when did the hands change such that they no longer ended in claws, but only phalanges supporting feathers? As more and more fossil birds come to light the timeline of clawlessness becomes slightly clearer. It may not ever be definitively known when clawed wings gave way completely to feather only wings, but it would be interesting to discover. The claws of Jeholornis are fairly small and appear almost as an afterthought of development, but even this appearance does not make the phylogeny of clawed wings distinctly clearer. Regardless, Jeholornis is a small bird that still resembles a dinosaur in many ways and has, through a bit of luck, been preserved in significant numbers in the fine sediments of the Hebei Province.

Slabs for Writing

The preservation of exquisitely fragile animals like birds (and pterosaurs, silly flying animals) is usually done with such fine sediments that the fossils are often found and removed as slabs of material. After those slabs are opened there is typically a slab, holding the actual fossil, and a counterslab that holds an impression of the fossil; this is where our wonderful feather impressions are most often found, though they have been known to come from the slab containing the fossil as well. Many of the remains of Jeholornis that have been procured, and certainly the ones that have been described, are found in this kind of arrangement. This is the reason also that so many of those papers are wonderfully descriptive and have such beautiful, for a crushed fossil bird, images of the fossil remains that are being described at the time. These include comparison papers between birds (Archaeopteryx vs. Jeholornis) as well as the straight descriptions of Jeholornis.

Using up the Documentaries

Yesterday I shared a video that was probably the best video that is easy to get to online featuring Jeholornis; it was a clip from Dinosaur Train which may make it seem a little sad. However, there is also a hybrid edited video that an internet denizen put together on Jeholornis. It may actually feature another animal in some parts of it, but that is okay, as it is done fairly well and shows a very similar animal if nothing else. Watch it and let us know what you think about it:

The animal that comes from the BBC clips is undoubtedly a different early/near bird, but I cannot place it for one reason or another and it would be wonderful to get a memory boost!

Too Much Fame

Jeholornis is so well known in the public domain that finding simple fact files or short essays describing the small primitive bird is actually quite difficult. The problem is that there are just too many links online. Some of the quick and simple pages that stand out right away come from About and the Encyclopedia of Life. The article from the EoL is not much edited from the original Wikipedia article, but it is still worth reading. Jeholornis has even shown up everywhere in videos, meaning that we can look to videos as well to learn about this bird. There are not any that I recommend above others, but there is a good episode of Dinosaur Train in which Jeholornis features prominently. I would certainly recommend watching it with the little paleontologists in your life today! You can find that video at this link.

Flying and Chasing

(C) Emily Willoughby

Jeholornis is hypothesized to have been a seed eating bird with a long tail and claws on its wings. The long tail and the claws on the wings are more than a hypothesis, of course, as they are present on many of the slab fossils that have been described and published. The other 93 plus unpublished specimens could have wonderful claws and tails, but we may not know for a very long time. The nicest fossils are published on first, which we should expect, and those beautiful fossils have painted a wonderful picture of an active little early bird. As stated at the start of this entry, the hypothesized diet of Jeholornis included seeds with a potential ability to ingest the leaves of plants like gingko themselves. In this image our favorite little bird (for this week) is actively eating gingko leaves off a small branch. Not knowing that that plant was gingko, it may also appear as though this Jeholornis is staring down the dragonflies on the tree it is standing near. Regardless, the long tail with its short caudal retrices and the claws on its wings are well represented here. The images of these traits could be slightly different depending on the illustrator, but I chose this image because I think it does a great job of representing the anatomy.

Long Tails and Little Teeth

The bird from Jehol, a region in China (now Hebei Province), was turkey sized and capable of powered flight. Despite having teeth Jeholornis had a diet consisting of mostly seeds. Their long tails, however, were used for flight, and were therefore much more bird-like than their teeth. Regardless, the main attraction of Jeholornis was neither its long tail nor its mouth that contained small teeth. Their claim to fame was is their clear flight abilities and the fact that that powered flight was achieved with well preserved feathers. Those feathers are asymmetrical, an important adaptation in powered flight.The other important characteristic associated with Jeholornis is the shear number of specimens and the variety that may (only seven have been described) be preserved in those specimens is a very intriguing and important for the history of birds. This week's bird is also quite beautiful, as far as delicate bird fossils go.

From O'Connor, et al. 2013

Like an Ostrich of Doom

Whenever a bird is popular, or any fossil animal for that matter, it is always fun to look at extant birds to see what kind of similarities there are in the two popular taxa. Terror birds in general are most reminiscent of ostriches and other ratites. What we really care about on Thursday is the popularity of the animal and whether or not there is evidence of that popularity out in the wide world. We know, with the television, improvised cards for games like YuGi-oh, and even the creation of video game characters (we have not seen a good Spore creature in a while). Titanis is a very popular bird and, being the only terror bird from North America, it is quite unique. Also, look at this hypothetical baby, he is adorable:

Strange Ideas

There was a hypothesis once that Titanis, and other Phorusrhacids, may have had a theropod-like claws at the end of their wings. This hypothesis came to light because the writs was considered to be extremely rigid and supposedly lacked the ability to fold against the body like a traditional wing. However, extant "terror birds", the seriemas of South America, do not possess a clawed manus at the end of their wings despite a largely unchanged wing and wrist. In fact, looking at a seriema is in a way looking at a scaled down, though no less vicious, version of their ancestors of the past. These living birds possess short wings and elect to fly-hop when they do leave the ground, which is rare. The idea that Titanis may have had wings weak enough to restrict flight but strong enough to allow for fly-hopping to slightly higher structures makes the speedy predator slightly more frightening as it adds a vertical component to its domain. Aside from obstacle avoidance, such an ability would have probably been most useful in nesting habits and, though its weight would have likely been too much for a typical branch, the bird could have built enormous nests that required fly-hopping to gain the apex of. The idea of a bird that large flying even an insignificant distance vertically is nearly preposterous though, and in all likelihood Titanis never left the ground on purpose. Regardless, the North American terror bird was more than capable of inflicting damage on prey items without clawed hands or the ability to chase other animals into trees.

Titanic Research

A great deal of research has been conducted regarding Titanis walleri over the years. The bird's body has been discussed many times over for many different reasons, but mostly for descriptions of the known skeleton and its relationship to other Phorusrhacids. Beyond descriptions many have studied the age of the birds and their genus. Some of the most cursory treatments of the bird are actually references in papers on the "Great American Interchange" that occurred when South American and North America came into contact with one another for the first time.

People Hate Television

People always have complaints about their favorite fossil animals on television. Documentaries, news reports; I have been critical in the past as well of these sorts of outlets. I have to say that in preparation for the clip I am going to put up here today. It is not terribly accurate, but it is good television, in terms of "hey that's a neat idea" not in terms of "hey that's entirely scientifically accurate". That being laid out there, try to enjoy this clip from the BBC series Primeval.

Titanis in Motion

Titanis facts can be found littered about the internet. There are all kinds of reading levels represented ranging from the everyone friendly About to the literature-like Prehistoric Wildlife. Medium level pages can be found at Fossil Treasures of Florida and the Florida Museum of Natural History. I know some people are more interested in hearing from the scientists that love these fossil animals, or at least know them very well. To address those concerns, we can watch this Luis Chiappe interview about the Titanis that was featured in the BBC show Primeval (we can look that up tomorrow):

Silhouetting Terror

(C) Tuomas Koivurinne

Throughout the course of this blog we have never been disappointed by the art of Tuomas Koivurinne. A bird like Titanis could be illustrated in either very magnificent poses or in some fairly stereotypically mundane poses. Combining the two (awesome bird and awesome artist) we get to see a view that is as magnificent as the skeletal remains indicate the bird to be. More often than not with birds the best illustrations draw on numerous versions of pigmentation hypotheses; featuring parrot-like terror birds that are almost more colorful than they are deadly. This illustration takes the worry of correct coloration and pigmentation away, for the most part, leaving us with a Titanis that could be anywhere between a crow-like jet black and perhaps a slightly lighter brown. Either way, of course, the sunset has hushed the tones of the feathers and the bird itself is silhouetted perfectly against the sky. It is not silhouetted so much that the important aspects of the terror inspiring of the bird have been subdued. The angry looking eyes, under their broad superorbital shelf of bone are plainly seen and they are looking angrily over the foreground and up at the sky. The broad bill and large feet are also clearly evident, though the feet are not particularly highlighted. The feet, mostly used for running, would have been used to crush and hold prey items under the weight of the bird as well as the power of the legs. The feet would have been quite a dual threat. The bill was most likely used as a hatchet (special thanks to Federico "Dino" Degrange for describing the Phorusrhacid bill at our meeting last week) to stun and kill prey. The wings of this bird were, as they are with many Phorusrhacids, atrophied and weak. Unlike those of ostriches, this running bird did not use its wings, it would appear, to balance as significantly while running at high speeds. A viable alternative hypothesis to this idea is that the smaller wings actually caused less drag than the large wings of an ostrich. However, it may just be that we have the wings incorrectly described in Titanis. My idea of drag could be completely incorrect also, but I will leave someone else to test that hypothesis or look up the literature on ostrich wing drag.

Holiday Birds

(C) Amanda (Flickr user spakattacks)

In the United States the time between November and December is a very bird-oriented time frame. There are turkeys and geese as well as official bird counts spread throughout the calendar. To celebrate this avian rich space on the calendar we ought to celebrate the fossil record of birds as well. To begin that celebration of birds we first turn toward one of the largest birds known to have existed. Coming, unexpectedly, from the group of predominately South American birds known as Phorusrhacids, the North American bird Titanis walleri Brodkorb 1963 was a wonderfully large and agile bird and one of few members of the family known to inhabit North America. Living from the Pliocene into the Pleistocene, Titanis was approximately 2.5 m (8.2 ft) tall and was estimated to weigh approximately 150 kg (330 lbs). The musculature of the animal must have been significantly well developed and toned as the bird's top speed was estimated to top out around 65 km/h (40.3 m/h); a respectable speed for a bipedal animal of any kind. It was, in addition to its size, solidly built, making the case for significant musculature even more well developed.

Why those Teeth?

What makes an animal develop the way it does is not as much of a mystery as it once seemed to be, but with an animal like Thylacosmilus there is still a healthy dose of skeptically looking at the teeth and thinking something like "Why would you possibly find that to be a beneficial morphology?" Plenty of researchers worldwide that are interested in either marsupials or carnivorans have asked many questions about the teeth of Thylacosmilus. The teeth of the morphologically similar saber-toothed cats are well studied and their extension beyond the mandible "makes sense" in comparison with that of Thylacosmilus. However, despite the clearly evident amazing morphology of these sabers, there are very few highly publicized papers on the dentition of these carnivores. That paper is actually an overview paper of many taxa, but it is still worth a read. Instead, research on the animal has focused on the brain, the ear (knowing how well a carnivore heard is integral to knowing aspects of their hunting ecology), and the postcranial skeleton. I admit that knowing the postcranial skeleton is very important for a variety of reasons (e.g. knowing that the animal was a marsupial, body shape), but there are a lot of different areas of this animal that continue to be very interesting. One of the best sources for today is, as most scientific books are, a relatively rare and harder to find text. The book is called Predators with Pouches and, while not a perfect source, covers Thylacosmilus quite well. Covering man extant animals, it also discusses extinct marsupial predators and does an acceptable job. Unfortunately, even the electronic book is over $140, which is normal for low volume scientific books. However, check out what can be seen online and try to enjoy it, even when a page you want to read is missing.

Reconstruction of Skeletons

Videos on this popular felid-like marsupial are not often professionally created. That does not stop people from putting up videos of the animal, however. These videos are often quite badly done though, as a result, and are of the type that are often associated with terrible music choices where the volume has been left at the highest possible setting and the illustrations are not even always of the fossil animal in question. The best representation of Thylacosmilus that was available today was actually shown in a video of a skeletal display piece of the animal from Museo Municipal Punta Hermengo de Miramar. My knowledge of Argentinian town systems is awful, but it appears that this museum is in a town known as Miramar south of Buenos Aires in General Alvarado Partido (partido being a lower level administrative district of Buenos Aires). I like to learn about these kinds of things. Regardless, the museum put up this video of the display being prepared and set up and it is interesting to look at the entire skeletal display. The area in which the museum is located is an area in which fossils of Thylacosmilus have been found, making the display that much more poignant. The lateral view of the teeth and corresponding mandibular structures are not perfect in this display, but are rather interesting and beg the question of why such an arrangement would have come to exist.

Facts About Thylacosmilus

(C) Angie Wilson

Amazingly Thylacosmilus is exceedingly popular on the internet, so much so that it has almost more pages dedicated to it than its more popular look-alike Smilodon. The pages dedicated to it range from encyclopedia type entries to much more open grouped facts compiled into short paragraph forms. The timeline for Thylacosmilus is presented in various forms, such as this one from Dinosaur Jungle (despite not being a dinosaur). The most interesting thing about Thylacosmilus is, of course, the teeth. The marsupial was smaller than Smilodon, but the teeth were similarly sized, but would have had to have been used in completely different ways. This will be discussed in much greater detail tomorrow and Tuesday, as there is a lot of different literature and movies showing those teeth. However, I encourage discussing this with kids over some interesting coloring pages, like these:

Fur-bearing Finale

December will not start until after the next week begins. However, this is going to be the last No-shave November mammal week that we are going to have here this year. This week's animal is an interesting carnivore. In fact, it is one of the more popular carnivores that existed during the Cenozoic, though not the most famous of its family. We have previously discussed Smilodon, and this week we examine its cousin, the interestingly jawed Thylacosmilus. The name is not widely known, but the odd mandibles of Thylacosmilus atrox and its family (Thylacosmilidae) have been found for nearly a century and are well known. The Miocene to Pliocene cat-like animals inhabited South America and were, amazingly maybe, marsupials. Their resemblance to cats is actually quite a coincidence. Their gape is a rather interesting conundrum, considering their teeth, and their bite force is extremely weak for their size. This is going to be a week of examining the weak and discovering what makes a marsupial so very much like a cat. Look at that adorable little face:

Released into public domain by: ДиБгд

Not So Popular Otters

Pretty much all of the evidence we saw this week pointed toward our lovely large otter Potamotherium being a rather large mustelid rather than a small basal pinniped. The fact that it is a mustelid may impact the popularity of the animal (seals and sea lions in particular are more popular than river otters) as may have the fact that it is a mammal. People tend to love mammals, but they seem to shy away from fossil mammals and turn to the reptiles of the past in terms of what they most often love and awe in paleontology. This is okay, but a bit strange. It also makes interesting furry animals like Potamotherium a lot less successful in the popular science domain than many other animals. The smaller size of Potamotherium makes it easier to disregard as well, though there is no evidence for this kind of trend existing. As a parting note for this week, here is an illustration that was shown earlier in the week with one of the animal's vertebrae. It is pretty spiffy.

Skulls and Fur

Potamotherium valetoni saint gerand le puy Musee d'Histoire Naturelle, Paris

The idea of Potamotherium being covered in fur is directly related to the fact that it is defined as a mammal. The mammalian nature of the animal can be seen in its head, including the teeth, and otter-like body. The head is extremely otter-like. The fact that early pinnipeds had similarly shaped heads and bodies is the only reason that Potamotherium has been confused for a pinniped in the past. However, the skull of Potamotherium is equally, and I assume more appropriately, mustelid-like and has caused the animal to be categorized as a mustelid. In terms of looking like an otter we know that the skull is very similar to that of extant otter species. The resemblance would have been noticeable, though differences would have certainly been recognized as well. However, at 1.5m (5ft) long it was a very elongate version of the otter. Short nasal chambers have led to the inference that sense of smell in this animal must have been fairly weak. The eyes and ears, though, appear to be highly capable.

Favorites

As everyone not new here knows, I love a good old fashioned paper. The 1957 description of the anatomy of Potamotherium is not one of my all time favorites, but I do rather enjoy the thoroughness of a good anatomical description of an animal. Partially the allure is in the fact that Savage is painting a picture of animal that no one had seen at that time or had ever dreamed of seeing. This description and the fossil material would eventually enable other anatomists like Leonard Radinsky to study characteristics of the brains of these interesting mustelids (during Radinsky's time a pinniped influence in Potamotherium was not an issue). Potamotherium is a world traveler though. German scientists have discussed the animal as have the Italian journals and the Royal Society (one does not have to be European to publish in either of course).

No Videos

There are literally zero videos about Potamotherium. Small mammals really get ignored by the media and documentary makers. Sometimes small mammals show up in animated movies, but Potamotherium has not shown up as yet. Instead of extolling this fact, I think it is important to look at a similar, but certainly different, semi-aquatic mammal that lived during a similar time-frame but in a different area. The animal in question is Puijila darwini, a definitively diagnosed basal seal capable of walking on land (not flopping about like a seal/sea lion). Enjoy learning about this animal in this video and see if you can take what we have learned about Potamotherium and compare it with Puijila!

River Facts

The River Beast Potamotherium was an intriguing mammal, as extant River Otters and their cousins Sea Otters are as well. Its furry cuteness makes it an excellent animal to share and discuss today; it is kind of the opposite of the giant dinosaurs that kids like to learn about but is equally fantastic. The lesser known mammals of the Miocene have fewer fact pages associated with them typically, and despite its cuteness and popularity that we have seen so far, Potamotherium has very few fact pages as well. The Encyclopedia of Life has a few facts, but these are mostly simple classification and time frame facts. About's page has a more extensive fact page, but compared to most dinosaurs, this Potamotherium page is a bit sparse as well. However, Gregory Kvitko has produced a wonderful ink and paper, very otter-y, version of Potamotherium that can be colored while discussing the animal and the sparse facts:

Fossil What?

An animal related to otters, other mustelids, or potentially related to pinnipeds (e.g. seals and sea lions) could have many overall forms. Thankfully, of course, we have quite a few good quality fossils that allow for educated morphological guesswork on the part of illustrators and reconstruction artists. The body plan that has been inferred from these fossils is heavily favoring a body that is much like that of the North American River Otter. River Otters, like Potamotherium, have sleek elongate bodies that are aerodynamic. This allows for swimming in freshwater loaded with current systems, such as rivers, and also allows the animal to be reasonably quick as, in the case of River Otters, they chase fish in the cool river waters. Aside from being mammals, the way River Otters stay warm in those cold waters is with heavy, oiled fur that traps warm air in their coat and waterproofs the fur. The similarity between Potamotherium and River Otters makes a lot of sense; Potamotherium means "River Beast."

Giant Fossil Weasels

Technically we are not talking about a weasel or an otter (it is an otter-like creature though). This week we are discussing an extinct mustelid reminiscent of its descendants. These happen to be mustelids and/or pinnipeds, depending on the researcher that you ask. Potamotherium was a genus of carnivoran mustelids represented by the single species P. miocenium arising during the so-called "cat gap" of the Miocene. The "cat gap" is a part of the Miocene in which felids are noticeably absent. This era of time allowed other groups, like the mustelids, and Potamotherium, to assert themselves as more apex-like predators. Other large predators still roamed and kept mustelids in check, but the " cat gap" was a very important time in the evolutionary history of the mustelids and pinnipeds. Which group does Potamotherium belong to? We will examine the different opinions and findings that differentiate the placement of this large semiaquatic carnivore during the week. However, the fuzzy terror of other riverine, or maybe just freshwater fishes, was adorable at the same time as being scary and predatory.

Know Your Proboscids

Elephants, mammoths, and mastodons are all closely related. Considering that mammoths and mastodons died off so relatively recently that our very near (geologically of course) ancestors hunted and lived alongside the giant herbivores. There have been taste tests of frozen mammoths, but not mastodons. The reason for that is partly the relative abundance of frozen mammoths compared to frozen mastodons that have been discovered. In fact, living more often in close proximity to forests and away from open ground, large open rivers, and crossing frozen lakes less often than their mammoth cousins has most likely led to this far lower number of mastodon flash freezes and subsequent frozen mastodon dinners. Mastodons also likely stayed away from the more likely freeze areas because they possessed far less shaggy coats than their woolly cousins, causing them to live in warmer areas and it is hypothesized that mastodons died out partly because they froze to death as a species. This does not mean we do not have very well preserved mastodons; instead of freezing whole they seemed to have a propensity for falling into the La Brea Tar Pits. These tar pit skeletons and the other North American finds have led to a great understanding of the animals and increased their popularity and face in the popular sciences that we see on television and movies. Mammoths remain far more popular among the majority of kids, but we can chalk this up to Ray Romano's Ice Age character more in the modern era than anything else (in my opinion). Mastodons, though, are still well known and still popular because they are, like mammoths and elephants, charismatic megafauna. Someone in Fort Wayne, Indiana loved mastodons. The Indiana-Purdue campus at Fort Wayne (there are a number of the IUPU hybrid campuses throughout the state) mascot is a mastodon; ignore his curved tusks!

What is in Your Teeth?

The teeth of mammoths are composed of ribbon-like layers of enamel that create an interesting and highly effective grinding surface. Mastodons have very different teeth that are more well-suited to  shearing and tearing. Where mammoths have flatter surfaces with grinding ribbons inlaid into the enamel plates, mastodons possess multiple nearly conical cusps in their teeth that allow for plant materials to be caught between the cusps and torn, sheared really, by the chewing actions of the jaws. The dietary differences are briefly mentioned by Daniel Fisher in this video showing the different teeth. The second video shows the teeth isolated from the mandible. Watch each video and appreciate the differences! Also, a special thanks to Elizabeth Deering for sharing much more information about mammoth teeth than I could post here!

Mastodon Science Is Wonderful

One of the best thing about the recently extinct is that we tend to have a record that is usually a bit more tenable and therefore easier to study. That means I can excitedly share papers that discuss topics as wide ranging as protein sequences, hunting of mastodons, bone formation, and even evidence of butchering. The level of knowledge we can obtain from mastodons is astounding. The fact that we can use so many different methods and studies to explore the world and anatomy of mastodons. My favorite articles, as I repeatedly mention, are the descriptions. There is no way to get the type description that I have found yet, unfortunately. That kind of thing happens though when the naming article was written in 1792. There is an 1895 article discussing the species named by Robert Kerr which discuss the naming briefly. We can deal with that though, given the wealth of information that is available in the modern era.

Movies of Mastodons

Some days the movies find themselves and the post barely even needs any writing. Today, despite my knowledge of music, I had to be reminded that searching just "Mastodon" turns up a lot more music than animals in the first hits that come up. However, there are plenty of videos for the animal as well. Enough that, once the search was reconsidered, there were plenty of videos that came up. On the news front there are videos about mastodons that were dug up, fairly recently, in a Michigan yard. The find was a surprise to the owner, but he was pretty excited, as was the news. Prehistoric New York, aired on Discovery, featured an episode on mastodons living in what would become the city a mere 12,000 years later. There episode of the show was pretty interesting overall, but it is awfully high production (thankfully of course as concerns documentaries). It is a nice depiction, just about as nice as the Field Museum's display, shown and discussed in this video. Personally, I'm a fan of this video that mixes the initial search (music) with the animal search. Here is Troy Sanders (parental discretion certainly advised here):

Coloring the Mastodon

While most of the United States is watching football I encourage, as I always do, discussing and reading about the fossil animal of the week (I have nothing against football; I'm watching a game while I type). In terms of reading for this week, I highly suggest 10 Facts About Mastodons (contributed by Bob Strauss), BBC's page on the American Mastodon, and the Prehistory page of facts. Richard Conniff's page on the mastodons on Smithsonian.com. In addition to that reading, I would highly encourage taking a moment out of your day to color one of these great looking mastodon coloring sheets:

(C) Joseph A Garcia