Friday, October 02, 2015

Growth of the Hadrosaurid Maiasaura

Maiasaura, a model organism for extinct vertebrate population biology: a large sample statistical assessment of growth dynamics and survivorship. 2015. Paleobiology

Abstract [edit]: A histological sample of 50 tibiae of the hadrosaurid dinosaur Maiasaura peeblesorum allows predictions of annual growth and ecological interpretations based on more histologic data than any previous large sample study. Tibia length correlates well (R2> 0.9) with diaphyseal circumference, cortical area, and bone wall thickness, thereby allowing longitudinal predictions of annual body size increases based on growth mark circumference measurements.

With an avian level apposition rate of 86.4 μm/day, Maiasaura achieved over half of asymptotic tibia diaphyseal circumference within its first year. Mortality rate for the first year was 89.9% but a seven year period of peak performance followed, when survivorship (mean mortality rate= 12.7%) was highest. During the third year of life, Maiasaura attained 36% (x= 1260 kg) of asymptotic body mass, growth rate was decelerating (18.2 μm/day), cortical vascular orientation changed, and mortality rate briefly increased. These transitions may indicate onset of sexual maturity and corresponding reallocation of resources to reproduction.

Skeletal maturity and senescence occurred after 8 years, at which point the mean mortality rate increased to 44.4%. Compared with Alligator, an extant relative, Maiasaura exhibits rapid cortical increase early in ontogeny, while Alligator cortical growth is much lower and protracted throughout ontogeny.

Congrats to Holly, Liz, Jim and Jack on a great paper!

Wendiceratops PLOS t-shirt

Danielle Dufault's image of our Wendiceratops is now on a t-shirt for PLOS (Public Library of Science), the journal that published the original paper. The shirts will be given away to social media blogger/twitterers at the upcoming SVP conference posting for the journal.

Thursday, October 01, 2015

Wednesday, September 30, 2015

Debuted This Day (1960): The Flintstones

Read about Alan Reed, the voice of Fred Flintstone.

Born This Day: Charles Lapworth

Lapworth (Sept. 30, 1842 - March 13, 1920) was an English geologist who proposed what came to be called the Ordovician period (505 to 438 million years old) of geologic strata. Lapworth is famous for his work with marine fossils called graptolites.

By fastidiously collecting the tiny, colonial sea creatures, he figured out the original order of layered rocks that had been faulted and folded in England's Southern Uplands. This method of correlating rocks with graptolites became a model for similar research throughout the world.

In 1879, Lapworth proposed a new classification of Lower Paleozoic rocks with the Ordovician, between the redefined Cambrian and Silurian periods. The name comes from an ancient Welsh tribe, the Ordovices. From Today In Science History

Monday, September 28, 2015

Uncovering The Original Colour of Fossil Organisms

Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils. 2015. PNAS.

Researchers discovered the reddish brown color of two extinct species of bat from fossils dating back about 50 million years, marking the first time the colors of extinct mammals have been described through fossil analysis.

The techniques can be used to determine color from well-preserved animal fossils that are up to 300 million years old, researchers said.

The researchers said microscopic structures traditionally believed to be fossilized bacteria are in fact melanosomes—organelles within cells that contain melanin, the pigment that gives colors to hair, feathers, skin, and eyes.
Read more at: Phys Org.