STL Science Center

STL Science Center

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.

11 November 2017

Birds and Thunder

©Nobu Tamura
In general, native peoples of both South and North America have a number of legends and mythologies describing giant flying animals. From the Thunder Bird (a generic term that encompasses a wide range of mythological figures from different tribes) to Tah-tah-kle'-ah (a race of cave dwelling "owl women" from Yakama lore) to Achiyalatopa (from Zuni folklore), native peoples have been influenced by the idea of giant birds flying across the sky. In some instances these are giant bird-men/women but regardless of the anthropomorphizing of giant birds, these legends could have been influenced by real living animals. One such giant flying bird has been discussed here before (See Pelagornis). Another giant bird, more often associated with the southern hemisphere but by no means entirely limited to that hemisphere, was Argentavis magnificens (Magnificent Argentinian/Silver Bird). Flying through the skies during the Late Miocene and known, at present at least, from only Argentina, Argentavis possessed a wingspan of approximately 6.07 m (19.9 ft) and 72 kg (159 lb) by the greatest estimates. This makes it the second largest flying bird ever known behind Pelagornis. In comparison to living birds, the largest wingspan is that of the Wandering Albatross at 3.65 m (12 ft) and the heaviest (sustained) flyer is the Kori Bustard at 11.4 kg (25.1 lb). At this size Argentavis must have flown much like Pelagornis; flapping powered flight may have gotten it airborne but thermal soaring would have been the most likely model for sustained flight.

10 November 2017

Iconic Images

Probably the best Bison latifrons image I have seen this past week (before looking tonight as I write this sentence) is that of Davide Bonadonna that I shared on the Facebook version of this page. Rather than paste it in here without contacting Davide, I will link his gallery where he hosts his illustrations. A large majority of bison illustrations are not as exciting as Bonadonna's or include modern bison being attacked by wolves (if not a hunting scene with Native Americans. In the "non-action but still fun" category one of the best images I have seen this week is Christopher DiPiazza's B. latifrons at the watering hole. I think I like this image more because it shows an interesting level of curiosity not often associated with the big brutish bison and also because it has softer tones that contrast with a lot of the images we have looked at over the course of the week. Please feel free to share more illustrations that you like in the comments.

09 November 2017

Documentaries Everywhere

I was considering what to do about the popular culture references today. There are a number of things that I could do, obviously, as we know that modern bison are something that the public is well aware of. I think, instead, that we should look at some documentaries which discuss the historical significance of bison as well as their current conservation status and situation. Though these documentaries do not specifically discuss the three species we have been discussing this week, the life history of extant bison is similar to that of their extinct family members and is therefore informative. The National Park Service covers a little history and their extant modern herds in the linked page. This second video, from the Kratt brothers (in their Wild Kratts series), may be a cartoon (mostly) but its appeal to the younger audience is not to be overlooked. The information that is given out in this video is useful, accurate, and does indeed go beyond it being a children's cartoon. There are also somewhat more traditional documentaries such as this "Fabulous Animals" show and Facing the Storm: the Story of the American Bison (which is movie length). I know that we are well away from extinct animals with these shows, but being able to see a modern descendant and how it lived on quite similar ground (ignoring the members of B. latifrons and B. antiquus found along the eastern seaboard) is important to trying to reconstruct the lives of the extinct animals.