Wenupteryx uzi, a Jurassic pterosaur from Patagonia.

Wenupteryx uzi, photograph of the slab. From Codorniu-Gasparini 2013.

By the Mid-Jurassic, Gondwana, the southern margen of supercontinent Pangea started to break up in different blocks: Antarctica, Madagascar, India, and Australia in the east, and Africa and South America in the west. During this period pterosaurs had a worldwide distribution, but their known record is markedly biased toward the northern hemisphere. For example, the ‘Solnhofen Limestone’ beds in Germany yielded important pterosaur specimens, mostly members of the genera Pterodactylusand Rhamphorhynchus. Other famous fossil-bearing deposits are from North America, and from the Tiaojishan Formation in China.

In contrast, the fossil remains of pterosaurs from Jurassic sediments are very scarce in the southern hemisphere. The oldest record comes from the Middle Jurassic of Patagonia, in the Cañadon Asfalto Formation, which is mainly composed of lacustrine deposits.

Wenupteryx uzi, reconstruction from Codorniú 2013.

The most complete pterosaur known so far is Wenupteryx uzi described by Laura Codorniu and Zulma Gasparini. In the Mapuche Languaje, Wenu means “sky” and uzi means “fast”.

Wenupteryx uzi, is a small pterosaur . The bones recovered so far are a nearly complete post-cranial skeleton,which includes: some cervical and dorsal vertebrae; a few thoracic ribs, a proximal right-wing (humerus, ulna and radius, right metacarpal IV, pteroid), a more complete left-wing and hindlimb bones. This pterosaurs has a wingspan approaching 1-10 m.
Based on the presence of some characters, like the depressed neural arch of the mid-series cervicals, with a low neural spine and elongate mid-series cervicals. Wenupteryx uzi is closely related to the Euctenochasmatia, which matches with Unwin’s phylogeny (Unwin, 2003).

References:

Laura Codorniú and Zulma Gasparini (2013). «The Late Jurassic pterosaurs from northern Patagonia, Argentina». Earth and Environmental Science Transactions of the Royal Society of Edinburgh 103 (3–4):  pp. 399–408. doi:10.1017/S1755691013000388.

Christmas edition: Geologizing with Dickens

Charles Dickens in his Study, 1859 by William Powell Frith. From Wikimedia Commons.

In the nineteenth century, Geology becomes very popular among the British society. Novels and newspapers often parodied scientists. One example of this is Professor Dingo, a very enthusiastic geologist from Charles Dickens’s novel Bleak House (1852-1853).

Dickens was a very important literary figure. He mixed with a great number of scientific men and women. Among his friends was Richard Owen. Dickens published some of Owen’s work in his periodical, Household Words and All the Year Round. Mr Venus, the taxidermist in  Dickens’s Our Mutual Friend (1864–65) was slightly based on Richard Owen. By the time when Dickens wrote this novel, Owen was the curator of the Hunterian Museum of the Royal College of Surgeons. Our Mutual Friend, also exhibits  traces of the work of Lyell, Jean-Baptiste Lamarck, and Darwin.

Cover of serial, “Bleak House” by Charles Dickens. From Wikimedia Commons.

Dickens, contributed to the popularity of geology with the creation of ideas and images for public consumption, such as he did in Bleak House, with the description of the streets of London where ancient lizards roamed, and volcanoes and quakes shocked the earth.

This is the opening paragraph:

“London. Michaelmas term lately over, and the Lord Chancellor sitting in Lincoln’s Inn Hall. Implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill. Smoke lowering down from chimney-pots, making a soft black drizzle, with flakes of soot in it as big as full-grown snowflakes—gone into mourning, one might imagine, for the death of the sun. Dogs, undistinguishable in mire. Horses, scarcely better; splashed to their very blinkers. Foot passengers, jostling one another’s umbrellas in a general infection of ill temper, and losing their foot-hold at street-corners, where tens of thousands of other foot passengers have been slipping and sliding since the day broke (if this day ever broke), adding new deposits to the crust upon crust of mud, sticking at those points tenaciously to the pavement, and accumulating at compound interest.”

It was the first appearance of a dinosaur in popular literature, but it was not until two years after the publication of Bleak House that the public saw the Megalosaurus reconstruction at the grand reopening of the Crystal Palace.

References:

Dickens, Charles, “Bleak House”, Penguin Books, 1994.

Buckland, Adelene , ‘“The Poetry of Science”: Charles Dickens, Geology and Visual and Material Culture in Victorian London’, Victorian Literature and Culture, 35 (2007), 679–94 (p. 680).

Brief paleontological history of planktonic foraminifera.

Neogloboquadrina dutertrei. (Credit: Dr Kate Darling).

Planktonic foraminifera made their first appearance in the Late Triassic. Although, identifying the first occurrence of planktonic foraminifera is complex, with many suggested planktonic forms later being reinterpreted as benthic. They are present in different types of marine sediments, such as carbonates or limestones, and are excellent biostratigraphic markers.

Their test are made of  globular chambers composed of secrete calcite or aragonite, with no internal structures and  different patterns of chamber disposition: trochospiral, involute trochospiral and planispiral growth. During the Cenozoic, some forms exhibited supplementary apertures or areal apertures. The tests also show perforations and a variety of surface ornamentations like cones, short ridges or spines.

The phylogenetic evolution of planktonic foraminifera are closely associated with global and regional changes in climate and oceanography.

The evolution of early planktonic foraminifera (From Boudagher-Fadel, 2013)

All species of Late Triassic and Jurassic planktonic foraminifera are members of the superfamily Favuselloidea. They present a test composed by aragonite, with microperforations, and sub-globular adult chambers. After the major End Triassic event, the Jurassic period saw warm tropical greenhouse conditions worldwide. The surviving planktonic foraminifera were usually dominated by small globular forms.

It was suggested  that a second transition from a benthic to a planktonic mode of life took place at the Jurassic, which occurred under conditions similar to those that triggered planktonic speciation in the Late Triassic (hot and dry global climate, and low sea levels).

During the Cretaceous,  the favusellids must have made the transition from being aragonitic to calcitic.  Also, in the Late Aptian there was a significant number of planktonic foraminiferal extinctions, but these were compensated by the establishment of a large number of new genera at the Aptian–Albian boundary.

Planktonic foraminifera from the Sargasso Sea in the North Atlantic Ocean. (Photograph courtesy Colomban de Vargas, EPPO/SBRoscoff.)

The Paleogene assemblage of planktonic foraminifera was derived from the few species that survive the mass extinction event at the end of the Cretaceous.

In the Early Miocene, the planktonic foraminifera were most abundant and diverse in the tropics and subtropics, and after the Mid-Miocene Climatic Optimum, many species were adapted to populate temperate and sub-polar oceans.

During the Middle and Late Pliocene, the final closure of the Central American seaway, changed oceanic circulation and drove a significant number of species extinctions. Most modern, living species originated in the Pliocene and Pleistocene.

References:

Armstrong, H. A., Brasier, M. D., 2005. Microfossils (2nd Ed). Blackwell, Oxford.

Boudagher-Fadel, MK; (2013) Biostratigraphic and Geological Significance of Planktonic Foraminifera. (2nd ed.)

An ichnological poem.

Oldhamia Antiqua, from Wikimedia Commons

The roots of ichnology lies between Art and Science. During the Renaissance, the study of Ichnology starts as an aesthetic appreciation of the traces. This can be found in the work of Leonardo, Aldrovandi, Gesner and Bauhin. In 1837,  Edward Hitchcock published “The Sandstone Bird”, probably the first ichnological poem and in 1880, Irish geologist and engineer John Joly wrote a beautiful sonnet  about the ichnogenus Oldhamia:

OLDHAMIA ANTIQUA

Is nothing left? Have all things passed thee by?

The stars are not thy stars! The aged hills

Are changed and bowed beneath repeated ills

Of ice and snow, of river and of sky.

The sea that raiseth now in agony

Is not thy sea. The stormy voice that fills

This gloom with man’s remotest sorrow shrills

The memory of the futurity!

We – promise of the ages! – Lift thine eyes,

And gazing on these tendrils intertwined

For Aeons in the shadows, recognize

In Hope and Joy, in heaven-seeking Mind,

In Faith, in Love, in Reason’s potent spell

The visitants that bid a world farewell!

John Joly (1857–1933) in his early twenties (from Wyse Jackson, 2007).

Oldhamia was described since the second half of the XIX century. This ichnogenus was named in honor to British geologist Thomas Oldham, and it’s mostly described in deep marine environments of the lower Cambrian. It’s produced by worm-like organism. Seilacher, in 2005, concluded that Oldhamia represents an ecological association which would become rare after the Cambrian agronomic revolution.

References:

Patrick N. Wyse Jackson (2011) History of Ichnology: John Joly (1857–1933) on Oldhamia: Poetic
and Scientific Observations, Ichnos: An International Journal for Plant and Animal Traces, 18:4, 209-212, DOI:
10.1080/10420940.2011.632795

When did the Anthropocene begin?

Image by Craig Mayhew and Robert Simmon (source NASA Goddard Photo and Video/Flickr)

The profound impact of human activity has motivated a concept that has been slowly emerging in science: human activities are a significant geological force.  In 1873,  Antonio Stoppani, an Italian Catholic priest and geologist, coined the “Anthropozoic era” to identify  the increasing power and impact of humanity on the Earth’s systems. Few years later, Joseph LeConte in 1879 proposed the term Psychozoic to describe the same phenomenon,  in 1922 Pavlov used the word Anthropogene, and Vernadsky in 1962 used  the term Noosphere. In 2000 Paul Crutzen – during a meeting of the International Geosphere-Biosphere Programme (IGBP) in Mexico – proposed use the term Anthropocene to designate the last two hundred years of human history and to mark the end of the current Holocene geological epoch. He and Stoermer placed the beginning of the Anthropocene at A.D. 1750–1800, when the Greenland ice cores registered a dramatic increase of carbon dioxide and methane.

Alternative temporal boundaries for the Holocene–Anthropocene boundary (calibrated in thousand of years before present) From Smith 2013

Ruddiman and Thomson (2001) argued that before the industrial revolution, human societies had a great influence on the earth’s atmosphere. They identified the inefficient wet rice agriculture as the most plausible source of increased anthropogenic methane input to the atmosphere while the rise in CO2 is attributed to the expansion of agricultural landscapes, almost 8000 years ago.

But other scientists pushed the boundary thousand of years before, like Christopher Doughty. He proposed in 2010 that the increase in Birch (Betula) pollen almost 14000 years ago reduced the reflectivity of the land surface causing a regional warming of 1º C. This phenomenon was associated with the disappearance of megafauna and because the extinction of mammoths is  linked to human predation, “human influence on global climate predate the origin of agriculture” (Doughty et al., 2010)

In 2011, Giacomo Certini and Riccardo Scalenghe  used soils to identifying the base of the Anthropocene in stratigraphic sequences, but this method was questioned due to the poor preservation potential of soils. And in an interview in 2012, Eugene Stoermer considered that the geological mark for the Anthropocene was the isotopic signature of the first atomic bomb tests.

Because the different start dates for the Anthropocene a consensus solution to establishing its lower boundary was proposed: “The Holocene and Anthropocene epochs could on practical terms be merged into the Holocene/Anthropocene epoch, easily and efficiently encompassing 10,000 years of human modification of the earth’s biosphere” (Ellis, 2013).

References:

Smith, B.D., Zeder, M.A., The onset of the Anthropocene. Anthropocene (2013), http://dx.doi.org/10.1016/j.ancene.2013.05.001

Ellis, E.C., 2011. Anthropogenic transformation of the terrestrial biosphere. Philosophical Transactions of the Royal Society A 369, 1010–1035.

Link:

The Anthropocene: Humankind as a Turning Point for Earth http://www.astrobio.net/interview/5530/the-anthropocene-humankind-as-a-turning-point-for-earth