STL Science Center

STL Science Center

21 November 2017

Papers on Dogs

Leptocyon was not much larger than a dachshund, with an estimated weight of approximately 3.26 kg (7.2 lb). The description of many websites stops after mentioning that fact and that its slender jaws and gracile body gave Leptocyon the appearance of a small fox. These are not the only characteristic attributable to Leptocyon however. The initial description and naming of the material is attributed William Diller Matthew in 1918 (see page 7 of the PDF). Matthew noticed the slender mandibles immediately and described the teeth and their morphology in detail. Matthew also states that the morphology of Leptocyon appears to make its inclusion as the ancestor to not only canids but also foxes, unlike some previous authors must have declared. As we have seen throughout the week up to now, most of the sources of information about Leptocyon are sources that describe the entire evolution of the canid family, not just descriptive works of the morphology or paleobiology of Leptocyon. Wang, et al. 2004 is a fairly well-known and (I have not checked into this recently) definitive description of the phylogenetic evolutionary ecology of all canids. It is a book chapter, but for the reader curious about Leptocyon or the dog enthusiast curious about where their pets came from, this is a good read with a lot of detail and a fair amount of technical elements to it.

19 November 2017

All Your Fox-like Facts

Leptocyon looked something like a fox, regardless of the species. There are no videos that show this fox-like species as scientific illustrations. There are a few videos that briefly mention Leptocyon, but the only one that is really worth watching is this video on the evolutionary history of canids; the mention is brief but the entire history of canids is worth watching on its own. ThoughtCo (previously About.com) is really the only dedicated website with detailed information on Leptocyon and the site hosts two webpages concerning the animal: one dedicated to the evolution of canids and a second with quick facts and images (and interpretations) of canids throughout history (Leptocyon is #12).

18 November 2017

Furry Friends and Megasymbol

Appearing in the Oligocene and peppering the fossil record into the Miocene (from approximately 25.8 - 10.3 million years ago), Leptocyon is a genus of small bodied canids endemic to North America. These canids, consisting of three species, L. gregorii, L. vafer, and L. vulpinus, represent the origins of the canine family tree as it diverged away from the feliniform carnivorans and the other caniforms. The caniforms include not only dogs, foxes, and wolves but also bears, seals and sea lions, and mustelids. For the approximately 15 million years of the fossil record that Leptocyon appears, it is the only canid that appears. Around the time that Leptocyon disappears from the fossil record an explosive diversification of foxes, wolves, coyotes, and wild dog begin to appear in the fossil record.

In the vein of an animal of importance to the native peoples of this continent, this precursor to so many different types of canines is the grandfather genus to many very impactful animals on the mythos and lore of those peoples. Wolves and coyotes are extremely important to many cultures of North America. Foxes, though, are just as important but not as prominently featured in Native American cultures as the other cultures. All of these animals star in other cultures globally (I wrote an honors thesis in undergrad on foxes in Japanese Shinto, for example) as well. Our discussion this week will elaborate on the origins of all of these animals from their humble beginnings in North America. The story of Leptocyon is the story of some of our favorite pets as much as it is the story of animals important to the native peoples of North America.

17 November 2017

Finding a Unique Illustration

©Christopher DiPiazza
Almost every illustration that comes up in a search for Argentavis depicts a bird landing or taking off with the few exceptions that show the animal simply stretching its wings one way or another; the bird on a dead animal trying to scare off scavengers is a very common theme. The large wingspan and body of the bird are central to the identity of the fossil, so these themes make sense. One of the most charismatic images that I have found does incorporate the wide wingspan of Argentavis, but it also has a piece of its last meal in its beak. Although almost all of the illustrations of Argentavis already looked fairly fierce, this interpretation, possibly because it was drawn head on, looks more intimidating and angry. As we typically see in Christopher DiPiazza's work, the tones and colors are soft and very pastel-like. Despite this, the details are sharp and the pose is dynamic. Additionally, read the linked blog post by the artist. He has hit a lot of the same points we have hit this week, but his insights into his art shine through in his writing, and they are worth reading about while admiring the work.

15 November 2017

Massive Eggs and Wings

The egg of Argentavis is estimated to weigh approximately 1 kg and it has been hypothesized that they were laid once every two years. At 1 kg the egg is only a little smaller than that of the Common Ostrich, but Argentavis' egg laying cycles were similar to gulls and albatrosses rather than animals that reproduce annually. It has been hypothesized that the incubation cycle of these eggs was such that the birds were forced to incubate over winter. Chicks were thought to have lived with the parents for approximately 16 months before permanently leaving the nest. By contrast, the Wandering Albatross is the longest fledging extant bird, with the young bird remaining in the nest for 278 days. As with many extant gulls and other seabirds, Argentavis is thought to have then had a sexually dormant period, not achieving maturity until approximately 12 years old; Royal and Wandering Albatrosses reach maturity between 6 and 10 years. The fact that Argentavis was so large means that most predation and death probably occurred either in the nest or by from accidents and old age. How old Argentavis lived to be naturally is up for debate, but we know that a lot of extant birds, large and small, live extremely long lives today. The Kakapo of New Zealand is thought to live well over 100 years; with so few in the wild and their histories not being cataloged until recently, however, the oldest known member was approximately 80 at his death. Other parrots have been known to live into their 80's in captivity and individual Royal Albatrosses have been documented at 58 years old in the wild. The largest flying birds, Great Bustards, live to approximately 10 years, whereas the oldest eagles have been recorded at between 30 and 40 years old (depending on the species). All of these numbers make pinpointing the ages of large birds, especially those that can fly, difficult. Argentavis could have lived a lifespan like that of a large eagle, meaning that it could have lived up to 40 years. That means that an adult pair, laying one egg every two years, could have possibly reared 14 young during their lifespan. Not only a large bird, Argentavis may have had a rather sizeable population at one time or another because of their long lives, large size, and dedication to a single offspring.

14 November 2017

Flying A Great Bird

One of the questions that appears time and again with giant flying animals is "How do they get off the ground and how do they stay off the ground?" Because that is a popular theme with large flying animals, the first hit in a paper search for Argentavis is Chaterjee, et al. 2007: The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina. The author's conclusions are centered around the hypothesized aspect ratio of the wing and estimated body weight. These parameters lead them to conclude that Argentavis was most likely similar to extant vultures and large condors in that it was probably not capable of sustained powered flight, instead choosing to use thermal soaring as its preferred method of staying airborne. Intermittent powered flapping would have been used as it is by these extant analogues as a secondary anti-stall measure but not as a power source for extended flight. This paper builds off of the new data and goes into more computer simulation than Vizcaino and and Farina1999, which initially tackled the problems of Argentavis flight without computer simulations, instead, it appears, relying on estimates of body size and inferred wing shape and comparing these with extant animals and known aerodynamic principals; the full text is not available anywhere online and what I have inferred comes from the abstract found here. The final article I will mention today addresses ecology (and reproduction). Palmqvist and Vizcaino 2003 details ranges, needed amounts of food, airspeeds, and clutch size to determine the ecological impacts and roles of Argentavis. Instead of spoiling this paper by writing in those facts, as I did above to a slight degree, I am going to simply encourage everyone to read and discover the paper's findings for themselves here. I find the paper to be interesting and find myself wondering if anyone would refute any of these findings; I have yet to find a paper that does so (I admit my search is short right now though).

13 November 2017

Quick Facts

Above are some quick facts about Argentavis presented in video form. This very quick video does not reveal much that we will not get into ourselves. There are some cryptozoology documentaries on the internet also; whereas these are strangely interesting, they are not necessarily historically accurate or important to watch in order to gain more knowledge about the bird. Aside from these kinds of videos and the short video shared here, most of the videos that show up with Argentavis as a keyword are related to video games.