Tommy Davidson
UW Madison Evolution Seminar Series, Spring 2012
First geological map of Patagonia drawn and colour-painted by Darwin, around 1840. (via Revista de la Asociación Geológica Argentina)
Hallucigenia
When: Early to Middle Cambrian (~540 to 500 million years ago)
Where: Found in what is now British Columbia and China
What: Hallucigenia is another odd fossil first known from the Burgess Shale formation of Canada. This largest individuals only reach 1.2 inches (~3cm) long, but there has been a lot of scientific debate centered around this tiny species. Before we get into the debate over its phyogenetic position, first we need to talk about which way is up! Or anterior for that matter. The first reconstructions of Hallucigenia had it walking on the stiff looking spiny projections, with the more flexible tentacles used to bring food to its mouth, which was reconstructed as being on a large bulbous projection. The modern interpretation is reversed in almost every way; it walks on the tentacle feet, the spines are on the dorsal surface for protection, and its head is on the opposite end. The modern reconstruction does not even have a large bulbous projection, as it is now thought the appearance of this blob in fossils is the inner organs of Hallucigenia being squeezed out though its posterior as it was flattened either at or after death. This strange form walked along the ocean floor, eating tiny food particles.
So now we /might/ know how this animal really looked… but what is it related to? Common suggestions have been: velvet worms (Onychophore), an extremely basal Arthoropoda, or as a member of a phylum now extinct. There is no firm consensus even today.
The Royal Ontario Museum recently put up a spectacular website on the Burgess Shale that you should check out if you would like to learn more about Hallucigenia and its contemporaries.
Deinotherium - Hoe tusker
When: Mid-Miocene to Early Pleistocene (~10 million to 3 million years ago)
Where: Asia, Africa, and Europe
What: Deinotherium is a proboscidiean. The only two living species in Proboscidiea are the African and Indian elephants, but there are dozens of fossil species in this order. Unlike some other groups that not only have a much greater number of fossil species than living but a much wider variety of morphologies to go along with that, most fossil elephants well… look like elephants! That being large, graviportal, and trunked.
However, even though there is less extreme differences in morphology within proboscidieans, there are still a lot of variations on the basic elephant body plan. One great source of variation is in the tusks. The tusks of Deinotherium are enlarged incisors of its lower jaw whereas in modern elephants the tusks are enlarged upper incisors. The clade containing Deinotheirum spilt off from the rest of the order roughly 40 million years ago, and the last common ancestor had slightly enlarged upper and lower incisors - thus it appears that some elephant clades further enlarged one set over the other. Oh, one last note about Deinotheirum… it was over 3 times the size of the modern african elephant. It was the 3rd largest land mammal ever to lumber accross the Earth!
(via scientificillustration)
After yesterday’s history lesson, we thought that you might want to relax and partake in some BMW arts & crafts.
- 1.) Download, print, cut, fold and have fun
- 2.) Don’t run with scissors
- 3.) Don’t put rubbing alcohol on paper cuts
- 4.) Repeat steps 2 and 3 if necessary
Don’t say I never gave you anything.
(via voiture-jaune)
1952 Mercedes-Benz 300 SL Prototype
Oxalis simplicifolia growing on a cliff at Ua Huka, Marquesas Islands, shows distinctive simple leaves, flowers and fruits. (Photo by Steve Perlman)
Ernst Haeckel
1962 angolan grand prix
My first paper. I feel happy of myself.
Ferdinand Lucas Bauer (1760-1826)
Banksia speciosa (Showy or Ricrac banksia), c.1811.
Watercolour on paper, 524 x 356 mm.
(Source: andibgoode, via scientificillustration)
