Tilly Edinger and the study of ‘fossil brains’.

 

Tilly Edinger (Photo,Museum of Comparative Zoology, Harvard University, Cambridge, MA)

Tilly Edinger (Photo,Museum of Comparative Zoology, Harvard University, Cambridge, MA)

Johanna Gabriele Ottilie “Tilly” Edinger was born on November 13, 1897 in Frankfurt, Germany. She was the youngest daughter of the eminent neurologist Ludwig Edinger and Dora Goldschmidt.

Edinger’s scientific interests led her to university studies in zoology and, later, in geology and paleontology. She studied at Universities of Heidelberg, Frankfurt, and Munich. In 1921, she received her Ph. D at the University of Frankfurt. When she was preparing her doctoral dissertation about the palate of the Mesozoic marine reptile Nothosaurus, Edinger encountered a skull with a natural brain cast. Her early research was mostly descriptive and she was influenced by the work of Louis Dollo and Friedrich von Huene.  After obtained her degree, she worked as a volunteer at the Geological-Paleontological Institute of the University of Frankfurt, and later as the section head in vertebrate paleontology at the Senckenberg Museum.

During her time at the Museum, she gathered references of several endocranial casts  treated as isolated curiosities  in earlier texts. Using stratigraphy and comparative anatomy, she organized them taxonomically and summarized the inferences that could be drawn from them. Later, in 1929,  she published Die fossilen Gehirne (Fossil Brains), the book that established Edinger’s membership in the German and international paleontological communities.

Endocranial cast (left) and brain of the living hellbender Cryptobranchus alleganiensis used by Romer and Edinger (1942) to document the relationship between the endocranial cast and the soft tissue brain in a living amphibian.

Endocranial cast (left) and brain of the living hellbender Cryptobranchus alleganiensis used by Romer and Edinger (1942) to document the relationship between the endocranial cast and the soft tissue brain in a living amphibian.

When the Nazi Party reached the power in 1933, Edinger continued working at the Museum thanks to protective actions of Rudolf Richter, Director of the Senckenberg Museum, but after the events that followed the infamous “Kristallnacht” (Night of the Broken Glass), her paleontological career in Germany ended abruptly.

Thanks to her pioneering works and the contacts she made from a previous trip to London in 1926, Edinger emigrated to England in May 1939. She started working at the British Museum of Natural History, alternately translating texts and working on her own paleoneurological projects.

In 1940, with the support of Alfred S. Romer, she moved to Massachusetts to take a position at the Harvard Museum of Comparative Zoology. Shortly after, she was the first and only woman who attend the founding meeting of the Society of Vertebrate Paleontology (SVP).

Edinger’s series of horse brains, showing differences in size and external anatomy as well as order of stratigraphic occurrence (Edinger, 1948)

Edinger’s series of horse brains, showing differences in size and external anatomy as well as order of stratigraphic occurrence.

Her second seminal work was written in 1948: “Evolution of the Horse Brain”.  Her work suggested that both brain enlargement and superficially similar patterns of cortical sulcation (surficial folds and grooves) had arisen independently in different orders of mammals (Buchholtz, 2001). 

Her knowledge of neuroanatomy allowed her to extend the range of information recoverable from endocasts. Based on the enlarged optic lobes and cerebellum of Rhamphorhynchus specimens, Edinger was able to predict their sensory dominance of sight and the possession of flight capabilities in pterosaurs.

By the early 1950s, she was not only the major contributor to the field of paleoneurology but also the mentor to a younger generation that was following in her footsteps. She received several honorary doctorates for her achievements, including Wellesley College (1950), the University of Giessen (1957), and the University of Frankfurt  (1964). She was elected president of SVP in 1963.

Tilly Edinger and colleagues at the Museum of Comparative Zoology. Sitting left to right: Tilly Edinger, Harry B. Whittington, Ruth Norton, Alfred S. Romer, Nelda Wright, and Richard van Frank. Standing left to right: Arnold D. Lewis, Ernest E.Williams, Bryan Patterson, Stanley J. Olsen, and Donald Baird. (Photo: David Roberts, from Buchholtz, 2001)

Tilly Edinger and colleagues at the Museum of Comparative Zoology. Sitting left to right: Tilly Edinger, Harry B. Whittington, Ruth Norton, Alfred S. Romer, Nelda Wright, and Richard van Frank. Standing left to right: Arnold D. Lewis, Ernest E.Williams, Bryan Patterson, Stanley J. Olsen, and Donald Baird. (Photo: David Roberts, from Buchholtz, 2001)

Tilly Edinger died in 1967 as the result of a traffic accident. She had 69 years old.  Her last book: “Paleoneurology 1804-1966. An annotated bibliography”, was completed by several of her colleagues and is considered the necessary starting point for any project in paleoneurology

References:

Buchholtz, Emily A.; Seyfarth, Ernst-August (August 2001), “The Study of “Fossil Brains”: Tilly Edinger (1897–1967) and the Beginnings of Paleoneurology”, Bioscience 51 (8)
Susan Turner, Cynthia V. Burek and Richard T. J. Moody, Forgotten women in an extinct saurian (man’s) world, Geological Society, London, Special Publications 2010, v. 343, p. 111-153

The sixth mass extinction: the human impact on biodiversity

800px-Ice_age_fauna_of_northern_Spain_-_Mauricio_Antón

Woolly mammoths in a late Pleistocene landscape in northern Spain (Author: Mauricio Antón) From Wikipedia Commons

At the beginning of the nineteenth century George Cuvier, the great French anatomist and paleontologist,  suggested that periodic “revolutions”, or catastrophes had befallen the Earth and wiped out a number of species, but under the influence of Lyell’s uniformitarianism, Cuvier’s ideas were rejected as “poor science”. One century after Cuvier definition of catastrophism, Chamberlain proposed that faunal major changes through time were under the control of epeirogenic movement of the continents and ocean basins. Despite Chamberlain’s article, the modern study of mass extinction did not begin until the middle of the twentieth century with a series of papers focused on the Permian extinction. One of the most popular of that time was “Revolutions in the history of life” written by Norman Newell in 1967.

Mass extinctions had shaped the global diversity of our planet several times during the geological ages. They are major patterns in macroevolution. Andrew Knoll defines them as perturbations of the biosphere which seem instantaneous when it is observed through the geological record.

The ‘‘Big Five’’ extinction events as identified by Raup and Sepkoski (1982)

The ‘‘Big Five’’ extinction events as identified by Raup and Sepkoski (1982)

In 1982, Jack Sepkoski and David M. Raup identified five mass extinctions. The first took place at the end of the Ordovician period, about 450 million years ago.  Now, according to the current rates of extinction, we are in the midst of  the so called “Sixth Mass Extinction”.

Mass extinctions are probably due to a set of different possible causes like basaltic super-eruptions, impacts of asteroids, global climate changes, or continental drift. But now, a group of scientists like Edward O. Wilson and Niles Eldredge identified post-industrial humans as the driving force behind the current and on-going mass extinction (Braje, 2013).

The human arrival was a “key component” in the extinction of the megafauna during the late Quaternary. In North America, approximately 34 genera (72%) of large mammals went extinct between 13,000 and 10,500 years ago, including mammoths, mastodons, giant ground sloths, horses, tapirs, camels, bears, saber-tooth cats, and a variety of other animals. South America lost an even larger number and percentage, with 50 megafauna genera (83%) becoming extinct at about the same time.

 

Richard Owen stands next to the largest of all moa, Dinornis maximus (now D. novaezealandiae). From Wikimedia Commons.

Richard Owen stands next to the largest of all moa, Dinornis maximus (now D. novaezealandiae). From Wikimedia Commons.

Other extinctions on island ecosystems around the world are result from direct human hunting, anthropogenic burning and landscape clearing, and the translocation of new plants and animals. One of the most famous and well-documented of these extinctions come from Madagascar. Pygmy hippos, giant tortoises, and large lemurs went extinct due to human hunting or habitat disturbance. A very interesting study by Burney et al. (2003) tracked the decline of coprophilous Sporormiella fungus spores in sediments due to reduced megafaunal densities after the human arrival on the island.  Another well documented case is the Moa extinction in New Zealand. Recent radiocarbon dating and population modeling suggests that their disappearance occurred within 100 years of first human arrival. A large number of  landbirds across Oceania suffered a similar fate beginning about 3500 years ago.

The anthropogenic effects increasingly took precedence over natural climate change as the driving forces behind plant and animal extinctions with the advent of agriculture and the domestication of animals.

The Panamanian golden frog (Atelopus zeteki). Credit: Brian Gratwicke. From Wikimedia Commons

The Panamanian golden frog (Atelopus zeteki). Credit: Brian Gratwicke. From Wikimedia Commons

Amphibians offer an important signal to the health of biodiversity; when they are stressed and struggling, biodiversity may be under pressure.   Today, they are the world’s most endangered class of animal, while corals have had a dramatic increase in risk of extinction in recent years. Some biologist predict that the sixth extinction  may result in a 50% loss of the plants and animals on our planet by AD 2100, which would cause not only the collapse of ecosystems but also the loss of food economies, and medicinal resources.

The acceleration of extinctions over the past 50,000 years, in which humans have played an increasingly important role, has left a number of hard questions about how the Anthropocene should be defined and whether or not extinctions should contribute to this definition (Erlandson, 2013)

 

References:

T.J., Erlandson, J.M., Human acceleration of animal and plant extinctions: A Late Pleistocene, Holocene, and Anthropocene continuum. Anthropocene (2013)

A.D. Barnosky, N. Matzke, S. Tomiya, G.O.U. Wogan, B. Swartz, T.B. Quental, C. Marshall, J.L. McGuire, E.L. Lindsey, K.C. Maguire, B. Mersey, E.A. Ferrer, Has the earth’s sixth mass extinction already arrived?, Nature, 471 (2011), pp. 51–57.

Mayhew, Peter J.; Gareth B. Jenkins, Timothy G. Benton (January 7, 2008). “A long-term association between global temperature and biodiversity, origination and extinction in the fossil record”. Proceedings of the Royal Society B: Biological Sciences 275 (1630): 47–53.

D.A. Burney, L.P. Burney, L.R. Godfrey, W.L. Jungers, S.M. Goodman, H.T. Wright, A.J.T. Jull, A chronology for late prehistoric Madagascar, J. Hum. Evol., 47 (2004), pp. 25–63

A brief introduction about the origin of Eukaryotes.

Sonderia sp. (a ciliate that preys upon various algae, diatoms, and cyanobacteria). Photo credit: Diana Lipscomb, George Washington University, Washington, D.C.

Sonderia sp. (a ciliate that preys upon various algae, diatoms, and cyanobacteria). Photo credit: Diana Lipscomb, George Washington University, Washington, D.C.

In 1883, the first person to suggested the endosymbiotic nature of eukaryotic cells was the German botanist Andreas Schimper, and in 1926 Russian botanist Konstantin Mereschkowsky and American biologist Ivan Wallin, postulated the idea that symbiosis is the main driving force of evolution in their book “Symbiogenesis and the Origin of Species”. In 1981, American Biologist Lynn Margulis published ”Symbiosis in Cell Evolution” and proposed that the complexity of the eukaryotic cell was assembled over a long time period by symbiotic associations between different kinds of prokaryotes and an amitochondriate protozoa host.

The mosaicism of the eukaryotic genome is challenging. Bacteria, Archaea, and Eukarya share common ancestry but they have very distinctive features. Eukarya are similar to Archaea for some systems like the replication, transcription,and translation apparatuses and to Bacteria for others like metabolism and membrane chemistry (Rochette, 2014), so the different hypotheses are associated with different phylogenomic prediction.

(a) The Serial Endosymbiotic Theory and (b) The Neomuran Hypothesis (from Armstrong 2005)

(a) The Serial Endosymbiotic Theory and (b) The Neomuran Hypothesis (from Armstrong 2005)

All these hypotheses can be classified into three main classes: hypotheses involving endosymbiosis, which argue that components of the eukaryotic cell arose by engulfment of prokaryotic organisms,  hypotheses for autogenous (‘self-birth’) pathways for eukaryotic cell components, and a “ternary” hypotheses suggest that the organism that engulfed the ancestor of mitochondria was itself a chimera of two prokaryotes.
The “hydrogen hypothesis” (Martin and Müller 1998) involves endosymbiosis and implies that ancestral eukaryotic genes are derived from the alphaproteobacterial ancestor of mitochondria and from the methanogenic euryarchaeon that hosted it. The Neomura hypothesis (Cavalier-Smith 2010b) is among the autogenous hypotheses and assumes that Eukarya are the sister group of all Archaea. Finally, a popular ternary hypothesis is the “endokaryotic” hypotheses in which the nucleus derives from an archaeon while the cytoplasm derives from a bacterium (Lake and Rivera 1994).
A recent analysis establishes that there is no phylogenomic support in favor of ternary hypotheses and support that Eukarya branch close to Archaea or basally within them and that some early-mitochondria hypotheses are compatible with current genomic data under certain assumptions (Rochette, 2014).

Cosmarium sp. (desmid) near a Sphagnum sp. leaf (Photo Credit: Marek Mis)

Cosmarium sp. (desmid) near a Sphagnum sp. leaf (Photo Credit: Marek Mis)

It’s possible that the last eukaryotic common ancestor (LECA) had a modern nucleus (Mans et al. 2004), a cytoskeleton based on microtubules and actin (Yutin et al. 2009; Hammesfahr and Kollmar 2012), a complete vesicle and membrane-trafficking system allowing for endocytosis (Dacks et al. 2009; Yutin et al. 2009; De Craene et al. 2012), mitochondria (which are derived alphaproteobacteria; Embley and Martin 2006; Gabaldón and Huynen 2007), a modern cell cycle (Eme et al. 2011), and a sexual cycle (Ramesh et al. 2005)

References:

Nicolas C. Rochette, Céline Brochier-Armanet, and Manolo Gouy, Phylogenomic test of the hypotheses for the evolutionary origin of eukaryotes, Mol. Biol. Evol. 2014 : mst272

Yonas I. Tekle,  Laura Wegener Parfrey, Laura A. Katz, Molecular Data Are Transforming Hypotheses on the Origin and Diversification of Eukaryotes, BioScience(2009),59(6):471 http://dx.doi.org/10.1525/bio.2009.59.6.5

The Rise of Oxygen and the early animals.

image_1413_1e-palaeosol

Iron formation from the Pongola Supergroup, South Africa. Credit: Nic Beukes/Univ. of Johannesburg.

Earth is the only planet in our Solar System with high concentrations of gaseous diatomic oxygen. Simultaneously, this unique feature of Earth’s atmosphere has allowed the presence of an ozone layer that absorbed UV radiations. But the oxygen content of Earth’s atmosphere has varied greatly through time. For about the first 2 billion years of Earth’s history, the atmospheric oxygen concentration was exceptionally low.

It’s widely assumed that about 2.3 billion years ago, the level of oxygen increased dramatically in a process called the Great Oxidation Event (GOE). This rise in oxygen level occurred during an episode of major glaciation known as the Huronian glaciation. The progressive oxygenation of the atmosphere and oceans was sustained by an event of high organic carbon burial, called the Lomagundi Event, which lasted well over 100 million years, and represents the largest positive carbon-isotope excursion in Earth history (Canfield, 2013). This early oxygen primary production  was exclusively conducted by prokaryotes, specifically by cyanobacteria.

Precambrian stromatolites in the Siyeh Formation, Glacier National Park. From Wikimedia Commons.

Precambrian stromatolites in the Siyeh Formation, Glacier National Park. From Wikimedia Commons.

However, new geochemical  evidence suggested that there were appreciable levels of atmospheric oxygen about 3 billion years ago, more than 600 million years before the Great Oxidation Event, indicating a greater antiquity for oxygen producing photosynthesis and aerobic life.

After the GOE, oxygen levels rose again and then fell in the atmosphere and remained at extremely low levels for more than a billion years. This was probably due to a particular combination of  biogeochemical feedbacks that spawned an oxygen-lean deep ocean (Lyons, 2014). The general oxygenation of the oceans began around 750-550 million years ago. This recovery  of oxygen levels led to a significant increase in trace metals in the ocean and possibly triggered the ‘Cambrian explosion of life’ (Large, 2014).

Halichondria panicea, a temperate marine demosponge (Photo: Daniel Mills)

Halichondria panicea, a temperate marine demosponge (Photo: Daniel Mills)

But early animals, in general, may have had relatively low oxygen requirements. According to new findings, a sea sponge – the living animal that most resembles the earliest animals on Earth – can live and grow even at atmospheric oxygen levels that are 0.5 percent of today’s levels, which challenges the notion that low oxygen levels were the limiting factor for animal evolution. The study also suggest that the evolution of sophisticated gene regulatory networks, may have controlled the timing of animal origins more so than environmental parameters  (Mills, 2014)

References:

Donald E. Canfield, Lauriss Ngombi-Pemba, Emma U. Hammarlund, Stefan Bengtson, Marc Chaussidon, François Gauthier-Lafaye, Alain Meunier, Armelle Riboulleau, Claire Rollion-Bard, Olivier Rouxel, Dan Asael, Anne-Catherine Pierson-Wickmann, and Abderrazak El Albani,  Oxygen dynamics in the aftermath of the Great Oxidation of Earth’s atmosphere PNAS 2013 110 (42) 16736-16741; published ahead of print September 30, 2013, doi:10.1073/pnas.1315570110.

Daniel B. Mills, Lewis M. Ward, CarriAyne Jones, Brittany Sweeten, Michael Forth, Alexander H. Treusch, and Donald E. Canfield, Oxygen requirements of the earliest animals, PNAS 2014 ; published ahead of print February 18, 2014, doi:10.1073/pnas.1400547111

Timothy W. Lyons, Christopher T. Reinhard, Noah J. Planavsky. The rise of oxygen in Earth’s early ocean and atmosphere. Nature, 2014; 506 (7488): 307 DOI: 10.1038/nature13068

Diatoms and Climate Change.

Diatoms living between crystals of annual sea ice in McMurdo Sound, Antarctica. From Wikimedia Commons.

Diatoms living between crystals of annual sea ice in McMurdo Sound, Antarctica. From Wikimedia Commons.

Diatoms are unicellular algae with golden-brown photosynthetic pigments with a fossil record that extends back to Early Jurassic. The most distinctive feature of diatoms is their siliceous skeleton known as frustule that comprise two valves. The formation of this opaline frustule is linked  in modern oceans with the biogeochemical cycles of silicon and carbon.

Because their abundance and sensitivity to different parameters,  diatoms play a key role in Paleoceanography , particularly for evidence of climatic cooling and changing sedimentation rates in the Arctic and Antarctic oceans and to estimate sea surface temperature. Also, diatom diversity can be used as a proxy for the influence of diatoms on marine export productivity and the carbon cycle.

Diatoms are thought to have diversified over the Cenozoic. Early Cenozoic oceans were relatively warm, but in the early to mid Eocene, ocean surface temperatures began to cool, and polar regions and tropical regions began to be more strongly differentiated. It was suggested that Late Eocene diatom proliferation likely occurred in response to subsidence of Southern Ocean land bridges and the concurrent development of circum-Antarctic upwelling.

Actinocyclus ingens Rattray and Thalassiosira convexa (SEM, Neogene diatoms from the Southern Ocean, ODP)

Actinocyclus ingens Rattray and Thalassiosira convexa (SEM, Neogene diatoms from the Southern Ocean, ODP)

Peak species diversity in marine planktonic diatoms occurred at the Eocene–Oligocene boundary followed by a pronounced decline, from which they have not recovered (Rabosky 2009).  During the early late Miocene, when temperatures and pCO2 were only moderately higher than today, diatoms lost about 20% of its diversity. Warmer oceans are linked with lower diatom diversity, suggesting that future warmer oceans due to anthropogenic warming may result in lower diatom diversity (Lazarus, 2014).

During the last 15 million years, diatom diversity is correlated with global carbon isotope record and with the past atmospheric pCO2, suggesting that diatoms have played a very important role in the evolution of mid-Miocene to Recent climate for their prominent role in the carbon pump.

References:

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

Lazarus D, Barron J, Renaudie J, Diver P, Türke A (2014) Cenozoic Planktonic Marine Diatom Diversity and Correlation to Climate Change. PLoS ONE 9(1):e84857. doi:10.1371/journal.pone.0084857

Egan KE, Rickaby REM, Hendry KR, Halliday AN (2013) Opening the gateways for diatoms primes Earth for Antarctic glaciation. Earth and Planetary Science Letters 375: 34–43. doi: 10.1016/j.epsl.2013.04.030

Women in the Golden Age of Geology in Britain.

A sketch of a Plesiosaur by Mary Anning, 1824.

A sketch of a Plesiosaur by Mary Anning, 1824. From original manuscripts held at the Natural History Museum, London. © The Natural History Museum, London

The nineteen century was the “golden age” of Geology. The Industrial Revolution ushered a period of canal digging and major quarrying operations for building stone. These activities exposed sedimentary strata and fossils. So, the concept of an ancient Earth became part of the public understanding and Literature influenced the pervasiveness of geological thinking. The study of the Earth became central to the economic and cultural life of the nation and in 1807, the Geological Society of London is founded with the purpose of making that geologists become familiar with each other, adopting one nomenclature and  facilitating the communications of new facts.

The most popular aspect of geology was  the collecting of fossils and minerals and the nineteenth-century geology, often perceived as the sport of gentlemen,was in fact, “reliant on all classes” (Buckland, 2013). Women were free to take part in collecting fossils and mineral specimens, and they were allowed to attend lectures but they were barred from membership in scientific societies. It was common for male scientists to have women assistants, but most of them went unacknowledged and become lost to history (Davis, 2009). However, some women found the way to cross that line and make a name in Geology.

Mary Elizabeth (née Horner) Lyell, (1808–1873), wife of Sir Charles Lyell, by Horatio Nelson King © National Portrait Gallery, London, and Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell, © 2014 The Natural History Museum.

Mary Elizabeth (née Horner) Lyell, (1808–1873), wife of Sir Charles Lyell, by Horatio Nelson King © National Portrait Gallery, London, and Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell, © 2014 The Natural History Museum, London.

The early female scientists belonged to wealthy families or they benefited from their associations. In the first group we could find Etheldred Benett of Wilshire (1776–1845), she described the stratigraphic and geographic distribution of fossils of Wiltshire. Although she was not formally published, Benett wrote several manuscripts, which are now in the collections of the Geological Society of London.

Barbara Rawdon (née Yelverton) Hastings (1810–1858), 20th Baroness Grey de Ruthyn and Marchioness of Hastings was known as a fossil collector and a “lady-geologist” . She is also well known for the “Hastings Collection,” consisting of several thousand fossil specimens from England and Europe. She also studied the stratigraphy of England and published her findings in “Description géologique des falaises d’Hordle, et sur la côte de Hampshire, en Angleterre” (Hastings, 1851–52) and “On the tertiary beds of Hordwell, Hampshire” (Hastings, 1853).

The Philpot sisters (Margaret, ?–1845; Mary, 1773?–1838; Elizabeth, 1780–1857) were also well know for their fossil collection and their friendship with Mary Anning. They lived in Lymes Regis and amassed an important collection of fossils from the Jurassic. Elizabeth maintained correspondences with William Buckland, William Conybeare, Henry De la Beche, Richard Owen, James Sowery and Louis Agassiz.

Skull of Crocodilus hastingsiae named by Sir Richard Owen, in honor to Barbara Hastings. Image from Wikimedia Commons.

Skull of Crocodilus hastingsiae named by Sir Richard Owen, in honor to Barbara Hastings. Image from Wikimedia Commons.

In the other group we could find those women who worked with their husbands. The most prominent of these women were Mary (née Moreland) Buckland (1797–1857), wife of Rev. William Buckland; Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell; Charlotte (née Hugonin) Murchison (1789–1869) wife of Sir Roderick Murchison; and Mary Elizabeth (née Horner) Lyell (1808–1873), wife of Sir Charles Lyell (Davis, 2009).

Mary Morland (1797–1857) illustrated some of George Cuvier’s work before she became Mrs William Buckland. She made models of fossils for the Oxford museum and repaired broken fossils. She assisted her husband by taking notes of his observations and illustrating his work. After the death of her husband, she continued working on marine zoophytes.

Charlotte Murchinson (1789–1869) was a strong influence for her husband and introduced him in the world of geology. She accompanied him on excursions and spent time sketching the  landscape and outcrops and collecting Jurassic fossil specimens from the beaches.

Mary Mantell (1795–1869) discovered the teeth of Iguanodon, which led to her husband’s publication of an important paper announcing the discovery of a new giant reptile (Creese and Creese, 1994). She also made the illustration of Mantell’s work: “Fossils of the South Downs: or Illustrations of the Geology of Sussex”. Mary Mantell left her husband in 1839 and the children remained with their father as was customary.

Mary Lyell (1808–1873) was daughter of the geologist Leonard Horner. She read both French and German fluently and translated scientific papers for her husband and managed his correspondence. She later specialized in conchology and regularly attended meetings of the London Geological Society.

Megalosaurus' jaw and teeth drawn by Mary Buckland. © Paul D Stewart / Science Photo Library

Megalosaurus’ jaw and teeth drawn by Mary Buckland. © Paul D Stewart / Science Photo Library

Mary Anning (1799-1847), was an special case. Despite her lower social condition and the fact that she was single, Mary became the most famous woman paleontologist of her time. She found the first specimens of what would later be recognized as Ichthyosaurus, the first complete Plesiosaurus, the first pterosaur skeleton outside Germany and suggested that the “Bezoar stones” were fossilized feces.

Fighting in their own way against the difficulties, women had contributed significantly to the development of geology and paleontology. Fortunately, geoscientists and historians are rescuing these woman from oblivion.

References:

BUREK, C. V. & HIGGS, B. (eds) The Role of Women in the History of Geology. Geological Society, London, Special Publications, 281, 1–8. DOI: 10.1144/SP281.1.

Davis, Larry E. (2009) “Mary Anning of Lyme Regis: 19th Century Pioneer in British Palaeontology,” Headwaters: The Faculty Journal of the College of Saint Benedict and Saint John’s University: Vol. 26, 96-126.

Buckland, Adelene: Novel Science : Fiction and the Invention of Nineteenth-Century Geology, University of Chicago Press, 2013.

A Brief Introduction to Paleoecology.

Duria Antiquior famous watercolor by the geologist Henry de la Beche based on fossils found by Mary Anning. From Wikimedia Commons.

Duria Antiquior famous watercolor by the geologist Henry de la Beche based on fossils found by Mary Anning. From Wikimedia Commons.

Paleocology is a multidisciplinary science. It involves the reconstruction of past environments from geological and fossil  evidence. A more exhaustive definition was given by Valentí Rull in 2010: “the branch of ecology that studies the past of ecological systems and their trends in time using fossils and other proxies”. Paleoecology can be used to investigate (1) the rates of speciation and extinction, (2) biome shifts and ecosystem development and (3) adaptation, migration, and population change (Seppä, 2009).

Charles Lyell (1797–1875) and Roman Fedorovich Gekker (1900-1991)

Charles Lyell (1797–1875) and Roman Fedorovich Gekker (1900-1991)

The major philosophical concepts in paleoecology are uniformitarianism, analogy, and parsimony. The concept of uniformitarianism was created by James Hutton (1726–97) and  Charles Lyell (1797–1875). It can be summarized as ‘the present is the key to the past’ and is the basic principle of paleoecology. The concept of analogy involves the application of modern organismic features to ancient organisms, and of course parsimony is a central rule for any scientific inquiry. In 1933, the Russian paleontologist Roman Gekker published the first book dedicated to paleoecology: “Manual to Paleoecology”, based in his lectures about the Devonian Period. In this book he established the main objectives of Paleoecology. Later, in 1954, he wrote “Directions for Research in Paleoecology” and in 1957, he published “Introduction to Paleoecology”.

Scanning electron microscope image of different types of pollen grains. Image from Wikipedia.

Scanning electron microscope image of different types of pollen grains. Image from Wikipedia.

There are two major types of paleoecology: Quaternary paleoecology, concerned with the last 2.6 million years of Earth’s history, and Deep-time paleoecology, based on fossils from pre-Quaternary sediments over a wide range of timescales (Birks, 2013). In the last four decades, quantitative methods for reconstructing environmental variables have been developed from a range of biological proxies such as pollen, plant macrofossils, insects (chironomids, coleopterans), molluscs, ostracods, diatoms, chrysophycean cysts, testate amoebae, and cladocerans preserved in lake sediments and peat profiles, or dinoflagellate cysts, diatoms, pollen, foraminifera, coccolithophores, and radiolarians preserved in marine sediment records.

Lago Sarmiento in Southern Patagonia. Sediment cores recovered from lakes like this, help to reconstruct environmental changes. Photo credit: R. Dunbar.

Lago Sarmiento in Southern Patagonia. Sediment cores recovered from lakes like this, help to reconstruct environmental changes. Photo credit: R. Dunbar.

The dominant technique in Quaternary terrestrial paleoecology is the pollen analysis. Pollen analysis involves the quantitative examination of spores and pollen at successive horizons through a core, particularly in bog, marsh, lake or delta sediments (Armstrong, 2005). This method was created by Lennart von Post (1884–1950), a Swedish geologist and presented at the 16th Scandinavian meeting of natural scientists in Oslo. Since the 1980s, many fossil pollen data sets were developed specifically to reconstruct past climate change.

Reference:

Seddon, A. W. R., Mackay, A. W., Baker, A. G., Birks, H. J. B., Breman, E., Buck, C. E., Ellis, E. C., Froyd, C. A., Gill, J. L., Gillson, L., Johnson, E. A., Jones, V. J., Juggins, S., Macias-Fauria, M., Mills, K., Morris, J. L., Nogués-Bravo, D., Punyasena, S. W., Roland, T. P., Tanentzap, A. J., Willis, K. J., Aberhan, M., van Asperen, E. N., Austin, W. E. N., Battarbee, R. W., Bhagwat, S., Belanger, C. L., Bennett, K. D., Birks, H. H., Bronk Ramsey, C., Brooks, S. J., de Bruyn, M., Butler, P. G., Chambers, F. M., Clarke, S. J., Davies, A. L., Dearing, J. A., Ezard, T. H. G., Feurdean, A., Flower, R. J., Gell, P., Hausmann, S., Hogan, E. J., Hopkins, M. J., Jeffers, E. S., Korhola, A. A., Marchant, R., Kiefer, T., Lamentowicz, M., Larocque-Tobler, I., López-Merino, L., Liow, L. H., McGowan, S., Miller, J. H., Montoya, E., Morton, O., Nogué, S., Onoufriou, C., Boush, L. P., Rodriguez-Sanchez, F., Rose, N. L., Sayer, C. D., Shaw, H. E., Payne, R., Simpson, G., Sohar, K., Whitehouse, N. J., Williams, J. W., Witkowski, A. (2014), Looking forward through the past: identification of 50 priority research questions in palaeoecology. Journal of Ecology, 102: 256–267. doi: 10.1111/1365-2745.12195

Seppä, H. 2009. Palaeoecology. eLS DOI: 10.1002/9780470015902.a0003232

Walker, Mike J. C., and John J. Lowe. 2007. Quaternary science 2007: A 50-year retrospective.Journal of the Geological Society 164.6: 1073–1092. DOI: 10.1144/0016-76492006-195

Wenupteryx uzi, a Jurassic pterosaur from Patagonia.

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

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.

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.

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.

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.

neoglobo

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.

planktonic foraminifera evolution

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.)

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.)