A palaeobotanical perspective on the Permian extinction.


Leaf bank of Glossopteris leaves (Adapted from Mcloughlin, 2012)

Leaf bank of Glossopteris leaves (Adapted from Mcloughlin, 2012)

The fossil record indicates that more than 95% of all species that ever lived are now extinct. Occasionally, extinction events reach a global scale with many species of all ecological types dying out in a near geological instant. These are mass extinctions. They were originally identified in the marine fossil record and have been interpreted as a result of catastrophic events or major environmental changes that occurred too rapidly for organisms to adapt. 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. A central question in the understanding of mass extinctions is whether the extinction was a sudden or gradual event. This question may be addressed by examining the pattern of last occurrences of fossil species in a stratigraphic section.

Jack Sepkoski and David M. Raup identified five major extinction events in Earth’s history: at the end of the Ordovician period, Late Devonian, End Permian, End Triassic and the End Cretaceous. The most recently identified mass extinction occurred during the Middle Permian, about  262 million years ago, and it was first recognised in the marine realm as a turnover among foraminifera, with fusulinaceans among the principal casualties.

Sin título

Total diversity patterns of continental diversity (solid line) and marine diversity (dotted line) at the family level. Arrows indicate the mass extinction events. (From Cascales-Miñana and Cleal 2015)

Extinction dynamics in the marine and terrestrial biotas followed different trajectories, and only the Permo-Triassic event coincided with a clear and abrupt diminution of both realms. Moreover, analysis of the paleobotanical record has suggested that plants may have suffered an additional extinction event, that is not reflected significantly in the marine realm, at the Carboniferous–Permian boundary. Evidence also suggests that  terrestrial environments suffered a single global pulse of extinction in the latest Permian, affecting both the fauna and flora (Cascales-Miñana and Cleal 2015).

During the end-Permian Event, the woody gymnosperm vegetation (cordaitaleans and glossopterids) were replaced by spore-producing plants (mainly lycophytes) before the typical Mesozoic woody vegetation evolved. The palynological record suggests that wooded terrestrial ecosystems took four to five million years to reform stable ecosystems, while spore-producing lycopsids had an important ecological role in the post-extinction interval. A key factor for plant resilience is the time-scale: if the duration of the ecological disruption did not exceed that of the viability of seeds and spores, those plant taxa have the potential to recover (Traverse, 1988).



Borja Cascales-Miñana, José B. Diez, Philippe Gerrienne & Christopher J.Cleal (2015): A palaeobotanical perspective on the great end-Permian biotic crisis, HistoricalBiology, DOI: 10.1080/08912963.2015.1103237

Aberhan M. 2014. Mass extinctions: ecological diversity maintained. NatGeosci. 7:171–172.

Cascales-Miñana B, Cleal CJ. 2014. The plant fossil record reflects just two great extinction events. Terra Nova. 26(3):195–200.

Darwin and the flowering plant evolution in South America.


Retimonocolpites sp. (Adapted from Llorens and Loinaze, 2015)

Charles Darwin’s fascination and frustration with the evolutionary events associated with the origin and early radiation of flowering plants are legendary. In a letter to Oswald Heer, a famous Swiss botanist, and paleontologist, Darwin wrote: “the sudden appearance of so many Dicotyledons in the Upper Chalk appears to me a most perplexing phenomenon to all who believe in any form of evolution, especially to those who believe in extremely gradual evolution, to which view I know that you are strongly opposed”. Heer discussed about the early angiosperm fossil record with Darwin, in a letter dated 1 March 1875: “if we say that the Dicotyledons begin with the Upper Cretaceous, we must still concede that this section of the vegetable kingdom, which forms the bulk of modern vegetation, appears relatively late and that, in geological terms, it underwent a substantial transformation within a brief period of time.” 

Darwin’s defense of a gradualist perspective led him to suggest that prior to the Cretaceous record of flowering plants, angiosperms had slowly evolved and diversified on a remote landmass. On 22 July 1879, in a letter to Joseph Dalton Hooker, Darwin refers to the early evolution of flowering plants as an “abominable mystery”. Nearing the end of his life, he wrote to Hooker another letter about a lost fossil record in the earliest phases of angiosperm diversification:  “Nothing is more extraordinary in the history of the Vegetable Kingdom, as it seems to me, than the apparently very sudden or abrupt development of the higher plants. I have sometimes speculated whether there did not exist somewhere during long ages an extremely isolated continent, perhaps near the South Pole.”

Letter from Charles Darwin to Joseph Dalton Hooker, written 22 July 1879 (provenance: Cambridge University Library DAR 95: 485–488)

Letter from Charles Darwin to Joseph Dalton Hooker, written 22 July 1879 (provenance: Cambridge University Library DAR 95: 485–488)

While the oldest records of the different groups of angiosperms are still in discussion, the outcrops of the Baquero Group, located in Argentinean Patagonia, contain one of the richest and most diverse Early Cretaceous floras in the Southern Hemisphere. The unit comprises three formations: Anfiteatro de Tico, Bajo Tigre and Punta del Barco. The first reports of angiosperm remains for the Anfiteatro de Tico Formation were made in 1967. The dominant types are Clavatipollenites, and Retimonocolpites.

Pollen grains  could enter into the fossil record by falling directly into swamps or lakes, or being washed into them or into the rivers and seas. The ones which are not buried in reducing sediments will tend to become oxidized and be destroyed. They reflects the ecology of their parent plants and their habitats and provide a continuous record of their evolutionary history. Gymnosperms pollen often is saccate (grains with two or three air sacs attached to the central body), while Angiosperm pollen shows more variation and covers a multitude of combinations of features: they could be  in groups of four (tetrads),  in pairs (dyads),  or single (monads). The individual grains can be inaperturate, or have one or more pores, or slit-like apertures or colpi (monocolpate, tricolpate).


Clavatipollenites sp. SEM (Adapted from Archangelsky 2013)

Clavatipollenites pollen grains are interpreted as related to the modern family Chloranthaceae. The genus was established by Couper for dispersed monosulcate pollen grains recovered from the Early Cretaceous of Britain. Currently, the genus has a very broad definition. The genus Retimonocolpites include elongated to subcircular semitectate, columellate and microreticulate pollen grains with well defined monocolpate aperture (Llorens and Loinaze, 2015). The new species Jusinghipollisticoensis sp. nov. represents one of the oldest records of trichotomosulcate, and extends the geographical distribution of Early Cretaceous trichotomosulcate pollen grains to southern South America.

The data also indicates strong similarities between the Baquero Group assemblages and other coeval units from Argentina, Australia and United States.


M. Llorens, V.S. Perez Loinaze, Late Aptian angiosperm pollen grains from Patagonia: Earliest steps in flowering plant evolution at middle latitudes in southern South America, Cretaceous Research 57 (2016) 66-78

Archangelsky, S.,et al. (2009). Early angiosperm diversification: evidence from southern South America. Cretaceous Research, 30, 1073-1082.

Doyle, J. A., & Endress, P. K. (2014). Integrating Early Cretaceous fossils into the phylogeny of living Angiosperms: ANITA. Lines and relatives of Chloranthaceae. International Journal of Plant Sciences, 175, 555-560.

HALLOWEEN SPECIAL III: Lovecraft, The Tunguska Event and The Colour Out of Space.

Tunguska forest (Photograph taken by Evgeny Krinov near the Hushmo river, 1929).

Tunguska forest (Photograph taken by Evgeny Krinov near the Hushmo river, 1929).

“And by night all Arkham had heard of the great rock that fell out of the sky and bedded itself in the ground beside the well at the Nahum Gardner place.”

“The Colour Out of Space” is a short story written by  H. P. Lovecraft in 1927.  The story is set in the fictional town of Arkham, Massachusetts, where an unnamed narrator investigates a local area known as the “blasted heath”. Ammi Pierce, a local man, relates him the tragic story of a man named Nahum Gardner and how his life crumbled when a great rock fell out of the sky onto his farm. Within the meteorite there was a coloured globule impossible to describe that infected Gardner’s family, and spread across the property, killing all living things. It’s the first of Lovecraft’s major tales that combines horror and science fiction. The key question of the story of course is the meteorite. Although “the coloured globule” inside the meteorite has mutagenic properties we cannot define their nature. But as Lovecraft stated once, the things we fear most are those that we are unable to picture.

H.P. Lovecraft’s love for astronomy is well known. As an amateur astronomer, Lovecraft attended several lectures from leading astronomers and physicists of his time. In 1906 he wrote a letter to the Scientific American on the subject of  finding planets in the solar system beyond Neptune. Around this time he began to write two astronomy columns for the Pawtuket Valley Gleaner and the Providence Tribune. He also wrote a treatise, A Brief Course in Astronomy – Descriptive, Practical, and Observational; for Beginners and General Readers. In several of his astronomical articles he describes meteors as  “the only celestial bodies which may be actually touched by human hands”.


“The Colour Out of Space” was published nineteen year after the Tunguska Event. On the morning of June 30, 1908, eyewitnesses reported a large fireball crossing the sky above Tunguska in Siberia. The object entered Earth’s atmosphere traveling at a speed of about 33,500 miles per hour and released the energy equal to 185 Hiroshima bombs. The night skies glowed and the resulting seismic shockwave was registered with sensitive barometers as far away as England. In 1921, Leonid Kulik, the chief curator for the meteorite collection of the St. Petersburg museum led an expedition to Tunguska, but failed in the attempt to reach the area of the blast. Later, in 1927, a new expedition, again led by Kulik, discovered the huge area of leveled forest that marked the place of the Tunguska “meteorite” fall. At the time, Kulik mistook shallow depressions called thermokarst holes for many meteorites craters. However, he didn’t find remnants of the meteorite, and continued to explore the area until World War II. In the early 1930s, British astronomer Francis Whipple suggested that the Tunguska Event was caused by the core of a small comet, while Vladimir Vernadsky, suggested the cause was a lump of cosmic matter. (Rubtsov, 2009). More than a century later the cause of the Tunguska Event remains a mystery.


The cover of “The Colour Out of Space” by Frank R. Paul, Amazing Stories, September 1927.

The enigmatic nature of the Tunguska Event inspired several fictional works. In the novel “Extinction Event”, a spin-off book for the science fiction series Primeval, the Tunguska event opened a gargantuan anomaly that periodically opens every few decades. The anomaly is linked to the late Cretaceous, just before the Cretaceous–Paleogene extinction event. The Tunguska Event was also included in two episodes of The X-Files (“Tunguska” and “Terma”). The show suggested that the incident was caused by an asteroid impact. In the plot, Fox Mulder and Alex Krycek traveled to the site of the impact, and discovered a military installation where Russian scientists study the black oil found inside the rock, which contained a microbial form of alien life capable of possessing a human body. In the episode “Piper Maru”, the same alien organism infected Krycek.

After 107 years, the Tunguska Event is still a mystery. Recently it was suggested that the Lake Cheko, a 300-m-wide lake situated a few kilometres from the assumed epicentre of the 1908 Tunguska event, is an impact crater, but several lines of observational evidence contradict the hypothesis.



Lovecraft, Howard P. (1927). “The Colour Out of Space”.

Joshi, S. T. (2001). A dreamer and a visionary: H.P. Lovecraft in his time. Liverpool University Press, 302.

Rubtsov, V. (2009): The Tunguska Mystery. Springer-Publisher: 318


Annie Montague Alexander, Naturalist and Fossil Hunter.


Annie Montague Alexander (Image: Gateway Science Museum)

Annie Montague Alexander was born on December 29, 1867, in Honolulu, Hawaii. She was the oldest daughter of Samuel Thomas Alexander and Martha Cooke. Both of her parents were the children of missionaries from New England who had come to the Hawaiian Archipelago in 1832. Her father pioneered in the raising of sugar cane on Maui, and founder of Alexander & Baldwin, Inc., one of the biggest companies in Hawaii.

Annie was educated at home by a governess until age fourteen, when she attended Punahou School in Honolulu for one year. In 1882, she moved with her family to Oakland, California. In the fall of 1887, she attended the Lasell Seminary for Young Women, a junior college in Auburndale, Massachusetts. At Lasell, she would join a close childhood friend from Maui, Mary Beckwith. During the two years she spent there she not enrolled in any science classes but studied nineteenth-century history, political economy, civil government, German, French, logic, dress cutting, and photography. Shortly after, she started to study painting in Paris. Unfortunately she began to suffer severe headaches after long hours at the easel and was warned of the possibility of blindness. Later, she enrolled in a training program for prospective nurses at a local hospital, but dropped after a short time and travelled to Europe with her family. In 1899 she met Martha Beckwith, the younger sister of her childhood friend,Mary Beckwith. They became great friends and both went on a trip to explore Oregon and California. Martha, a graduate of Mount Holyoke College, encouraged Annie to broaden her knowledge of the natural world. A year later, she started attending lectures at the University of California, becoming particularly interested in lectures on paleontology given by Dr. John C. Merriam. That was the beginning of the long relationship between Annie Montague Alexander and the University of California at Berkeley, a relationship that would prove exceptionally advantageous to both of them.


Annie Montague Alexander during a field trip to Nevada, 1905. (Image: University of California Museum of Paleontology, Berkeley)

At first, Annie limited her involvement to funding several of Merriam’s fossil hunting expeditions, but by the summer of 1901, Annie joined her instructor Dr. Merriam and Vance C. Osmont, an assistant professor of mineralogy at the University of California in a field trip to Shasta County, California. Then she financed and led her own expedition to the Fossil Lake region of southern Oregon. She and her group recovered over 100 fossils from a variety of extinct mammals, including miniature horses and camels. In a letter to Martha she wrote: “The fever for amassing these strange treasures might make of me a collector of the most greedy type, unmoved by ‘threats of Hell or hopes of Paradise.’”

The following summer, Annie financed and organized a new fossil collecting expedition to Shasta County in northern California.  She uncover three important ichthyosaur skeletons, including one nearly complete and exceptionally well-preserved specimen. After examining the skeleton, Merriam concluded that it was a new species of ichthyosaur, which he named Shastasaurus alexandrae in Annie’s honor. She organized a second field trip to Shasta County. Once again, she made an extraordinary discovery: a new genus of ichthyosaur. The fossil was named Thalattosaurus alexandrae as a tribute to Annie.

In 1904, she embarked with her father to a long safari to Africa. Her beloved father died during trip. To recover from her loss, Annie turned to the paleontological fieldwork. She later declared: “It is strange how absorbing this work is. We forget the outside world”.

Annie Montague Alexander on a 1923 expedition in France.

Annie Montague Alexander on a 1923 expedition in France. (Image: Alexander & Baldwin, Inc.)

In the fall of 1905, Annie met C. Hart Merriam chief of the United States Biological Survey. Then she financed a paleontological expedition to the West Humboldt Range in Nevada, to explore the Triassic limestones of the region. This trip, know as the  “Saurian Expedition,” was a great success. Under the leadership of Professor John C. Merriam, the group discovered twenty-five specimens of ichthyosaurs, including some of the largest in the world and the most complete ever found in North America. Annie, later wrote an account of the expedition, illustrated with her own photographs. During that time she met Joseph Grinnell, a young naturalist from Pasadena, California. Grinnell told her of the need for a natural history museum on the west coast. She became enthusiastic with the project and she insisted that the museum should be housed at the University of California. She and Joseph Grinnell would have complete control of the museum and its employees. The cost of the Museum of Vertebrate Zoology was covered almost entirely by Annie. A year later she helped to funding the Department of Paleontology and in 1921 she established the university’s Museum of Paleontology.

Annie’s last extended trip was in the winter of 1947—48 to Baja California, when she and her longtime companion Louise Kellogg  spent three months collecting more than forty-six hundred botanical specimens.

Annie Alexander died, on September 10, 1950, at the age of eighty-two. Her ashes were buried in Makawao Cemetery, Maui. Her contributions were recognized by zoologists and botanists, who named two mammals, two birds, six fossils, and two plants after her.


Barbara R. Stein, “On Her Own Terms. Annie Montague Alexander and the Rise of Science in the American West”. University of California Press, Berkeley, 2001
Rianna M. Williams, “Annie Montague Alexander: Explorer, Naturalist, Philanthropist”. Hawaiian Journal of History, volume 28, 1994.

A Brief Introduction to The Hell Creek Formation.

Hell Creek e Fort Union contact, as seen at Mountain Goat Lake Butte, southwestern North Dakota (Adapted from Fastovsky and Bercovici, 2015)

Hell Creek- Fort Union contact, as seen at Mountain Goat Lake Butte, southwestern North Dakota (Adapted from Fastovsky and Bercovici, 2015)

The Hell Creek Formation (HCF), in the northern Great Plains of the United States, is the most studied source for understanding the changes in the terrestrial biota across the Cretaceous-Paleogene boundary, because preserves an extraordinary record comprised of fossil flora, vertebrates, invertebrates, microfossils, a range of trace fossils, and critical geochemical markers such as multiple iridium anomalies associated with the Chicxulub impact event. The HCF is a fine-grained, fluvially derived, siliciclastic unit, that occupies part of the western Williston Basin, and overlies the Fox Hills Formation (Clemens and Hartman, 2014).
The history of research focused on the Hell Creek Formation and its biota started in October 1901, when William T. Hornaday, director of the New York Zoological Society, travelled to northeastern Montana and discovered three fragments of the nasal horn of a Triceratops in the valley of Hell Creek. He showed the fossils to Henry Fairfield Osborn who decided to include the valley of Hell Creek on the list of areas to be prospected by Barnum Brown the following year.

Barnum Brown working in a quarry in 1902.

In July 1902, B. Brown arrived to Hell Creek. His field crew included Dr. Richard Swann Lull, and Phillip Brooks. Brown recounted that after their arrival, he found the partial skeleton that would become the type specimen of Tyrannosaurus rex. In 1904, William H. Utterback, preparator and collector for the Carnegie Museum of Natural History, collected a fragment of a jaw of Tyrannosaurus and two skulls of Triceratops. In the summer of 1906, B. Brown returned to Montana, and a year later he published a complete manuscript about the valley of Hell Creek. The field expeditions of 1908 and 1909 were crowned by the discovery of another skeleton of T-rex. Between 1902 and 1910, Osborn, Brown, and Lull published the analysis of some of the fossil vertebrates discovered in the Hell Creek Formation, including Tyrannosaurus rex, Triceratops, and Ankylosaurus.
Micrograph of Wodehouseia spinata and a specimenBisonia niemi, from the upper part of the Hell Creek Formation (Adapted from Fastovsky and Bercovici, 2015).

Micrograph of Wodehouseia spinata and a specimen Bisonia niemi, from the upper part of the Hell Creek Formation (Adapted from Fastovsky and Bercovici, 2015).

Plants are represented by fossil leaves, seeds and cones. Fossil wood is also commonly found in the HCF as permineralized fragments. The Hell Creek macroflora is largely dominated by angiosperms including palms, associated with several ferns, conifers, and single species of cycads and Ginkgo. The study of pollen and spores has played a very important role in the identification of the K/Pg boundary in the HCF. Palynologists were the first scientists to recognize that a major, abrupt change occurred at the end of the Cretaceous. Unlike the Permian-Triassic and Triassic-Jurassic boundaries, the palynologically defined K/Pg boundary is based on the extinction of Cretaceous taxa rather than the appearance of Paleocene taxa. Intimately associated with the K/Pg boundary globally, is the so-called “fern spike”, occurring exclusively at localities where the iridium anomaly is present. (Fastovsky and Bercovici, 2015; Vajda & Bercovici, 2014.)



Fastovsky, D. E., & Bercovici, A., The Hell Creek Formation and its contribution to the CretaceousePaleogene extinction: A short primer, Cretaceous Research (2015), http://dx.doi.org/10.1016/j.cretres.2015.07.007
Clemens, W. A., Jr., & Hartman, J. H. (2014). From Tyrannosaurus rex to asteroid impact: early studies (1901- 1980) of the Hell Creek Formation in its type area. In J. Hartman, K. R. Johnson, & D. J. Nichols (Eds.), Geological society of America special paper: 361. The Hell Creek Formation and the Cretaceous-tertiary boundary in the northern great plains (pp. 217-245).
Husson, D., Galbrun, B., Laskar, J., Hinnov, L. A., Thibault, N., Gardin, S., & Locklair, R. E. (2011). “Astronomical calibration of the Maastrichtian (late Cretaceous)”. Earth and Planetary Science Letters 305 (3): 328–340.doi:10.1016/j.epsl.2011.03.008
Johnson, K. R., Nichols, D. J., & Hartman, J. H. (2002). Hell Creek Formation: A 2001 synthesis. The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the northern Great Plains: Geological Society of America Special Paper, 361, 503-510.

”Kunstformen der Natur” (Art forms of Nature).

Ernst Haeckel’s ”Kunstformen der Natur” showing various sea anemones classified as Actiniae. From Wikimedia Commons.

Ernst Haeckel’s ”Kunstformen der Natur” showing various sea anemones classified as Actiniae. From Wikimedia Commons.

”Kunstformen der Natur” (Art forms of Nature) was Ernst Haeckel‘s master work. Initially published in ten fascicles of ten plates each – from 1899 to 1904 -, coincided with his most intensive effort to popularise his monistic philosophy in Die Welträthsel and Die Lebenswunder. For Haeckel ‘Beauty’, constituted one of the three pillars of Monism, alongside the ‘Good’ and the ‘True’. Haeckel’s monism,  argued that there is no fundamental difference between organic and inorganic nature, that is, life differed from inorganic nature only in virtue of the degree of its organization. In the introduction to Kunstformen der Natur, Haeckel wrote: ‘Nature generates in her lap an inexhaustible abundance of wonderful forms, whose beauty and diversity surpass by far all art forms produced by man’. He firmly believed that a reformed, naturalistic art, would help to emancipate people from repressive political and religious authorities who maintain their domination over the people by fostering ignorance and superstition among them (Heie) He proposed that instead of Christianity, it should be monism that becomes the basis of education and civic life.

E. Haeckel's illustrations of forams: Thalamophora - Globigerina

E. Haeckel’s illustrations of forams: Thalamophora – Globigerina

Goethe was a strong influence in Haeckel, and leads him to think of Nature in anthropomorphic terms. At the beginning of Generelle Morphologie, Haeckel cited the words of the poet from his essay ‘Ode to Nature’:

Nature eternally creates new forms; what exists now has never before been; what was will not come again: everything is new and yet ever the old. In her there is an eternal life, becoming and movement. She is eternally changing, and never stands still for an instant. She has no concept for ‘remaining’, and she has placed her curse on standing still. She is firm: her step is measured, her laws unalterable. She thought and ponders constantly; not as a man, but as Nature. To everyone she appears in a particular form. She conceals herself in a thousand names and terms, and is always the same.

Haeckel’s experiences in Italy also had an enduring influence on the later formulation of his aesthetic theories. Other great influence was Alexander Humboldt’s Ansichten der Natur  (Aspects of Nature, 1808), in which Haeckel found  vivid depictions of the flora, fauna and geological features of the various topographical regions that Humboldt encountered during his research expeditions, most notably his famous excursion into the interior of South America between 1799 and 1804.


Ernst Haeckel – Kunstformen der Natur (1904), plate 99: Trochilidae .

But Haeckel was a man of contradictions. His belief in Recapitulation Theory (“ontogeny recapitulates phylogeny”) was one of his biggest mistakes. His affinity for the German Romantic movement influenced his political beliefs and Stephen Jay Gould wrote that Haeckel’s biological theories, supported by an “irrational mysticism” and racial prejudices contributed to the rise of Nazism. Despite those faults, he made great contributions in the field of biology and his legacy as scientific illustrator is extraordinary. “Kunstformen der Natur” (Art forms of Nature) influenced not only in science, but in the art, design and architecture of the early 20th century.

In 1908, Haeckel was awarded with the prestigious Darwin-Wallace Medal for his contributions in the field of science. After the death of his wife in 1915, Haeckel became mentally frail. Three years later sold his house to the Carl Zeiss foundation and it presently contains a historic library.



Breidbach, Olaf. Visions of Nature: The Art and Science of Ernst Haeckel. Prestel Verlag: Munich, 2006.

Heie, N. Ernst Haeckel and the Redemption of Nature, 2008.

Richards, Robert J.  The Tragic Sense of Life: Ernst Haeckel and the Struggle over Evolutionary Thought, (2008), University of Chicago Press.

Climate Change and the Evolution of Mammals.


Bighorn Basin, Wyoming (Image: University of New Hampshire, College of Engineering and Physical Sciences).

Rapid global climate change can lead to rapid evolutionary responses. The Paleocene-Eocene Thermal Maximum (PETM; 55.8 million years ago), was a short-lived (~ 200,000 years) global warming event attributed to a rapid rise in the concentration of greenhouse gases in the atmosphere. It was suggested that this warming was initiated by the melting of methane hydrates on the seafloor and permafrost at high latitudes. This event was accompanied by other large-scale changes in the climate system, for example, the patterns of atmospheric circulation, vapor transport, precipitation, intermediate and deep-sea circulation, a rise in global sea level and ocean acidification.

The PETM onset is also marked by the largest deep-sea mass extinction among calcareous benthic foraminifera (including calcareous agglutinated taxa) in the last 93 million years. Similarly, planktonic foraminifera communities at low and high latitudes show reductions in diversity, while larger foraminifera are the most common constituents of late Paleocene–early Eocene carbonate platforms.


Phenacodus by Heinrich Harder (1858-1935) . From Wikimedia Commons.

During the PETM, around 5 billion tons of CO2 was released into the atmosphere per year, and temperatures increased by 5 – 8°C. The rise in temperature coincided with a dramatic decrease in the body size of marine and terrestrial organisms. Dwarfing of mammalian taxa across the Palaeocene-Eocene Thermal Maximum (PETM) was first described in the Bighorn Basin, Wyoming. The basin has a remarkably fossil-rich sedimentary record of late Palaeocene to early Eocene age.  The interval of the Paleocene–Eocene Thermal Maximum is represented by a unique mammalian fauna composed by smaller, but morphologically similar species to those found later in the Eocene. Diminutive species include the early equid Sifrhippus sandrae, the phenacodontids Ectocion parvus and Copecion davisi. Two main hypotheses have been proposed to explain the observation of smaller body sizes during the global warming event. The first hypothesis is that mammal population decreased the average body-size in response to the environmental conditions that existed during the PETM global warming event. The second hypothesis is that the observed decrease in the average body-size was the result of extrinsic forces, such as the range extension of small species into the Bighorn Basin, displacing larger species (Burger, 2012). 

Comparison of the effects of anthropogenic emissions (total of 5000 Pg C over 500 years) and PETM carbon release (3000 Pg C over 6 kyr) on the surface ocean saturation state of calcite. From Zeebe, 2013

Comparison of the effects of anthropogenic emissions (total of 5000 Pg C over 500 years) and PETM carbon release (3000 Pg C over 6 kyr) on the surface ocean saturation state of calcite. From Zeebe, 2013

New findings revealed that the remarkable decrease in mean body size across the warming event, occurred through anagenetic change and immigration. However, species selection also was strong across the PETM but, intriguingly, favoured larger-bodied species, implying some unknown mechanism(s) by which warming events affect macroevolution (Rankin et al., 2015). 

Climate change is the major threat to biodiversity. The combination of global warming and the release of large amounts of carbon to the ocean-atmosphere system during the PETM has encouraged analogies to be drawn with modern anthropogenic climate change. Reduction in nutrients, food availability and water will probably have negative implications and are interrelated with climate change and shrinking organisms.  We need to understand how and why organisms are shrinking, and what it means for biodiversity and humanity.


Rankin, B., Fox, J., Barron-Ortiz, C., Chew, A., Holroyd, P., Ludtke, J., Yang, X., Theodor, J. 2015. The extended Price equation quantifies species selection on mammalian body size across the Palaeocene/Eocene Thermal Maximum. Proceedings of the Royal Society B. doi: 10.1098/rspb.2015.1097

Barnosky, A. D. 2004 Biodiversity response to climate change in the middle Pleistocene: the Porcupine Cave fauna from Colorado. Berkeley, CA: University of California Press.

Burger, B.J., Northward range extension of a diminutive-sized mammal (Ectocion parvus) and the implication of body size change during the Paleoc…, Palaeogeogr. Palaeoclimatol. Palaeoecol. (2012), http://dx.doi.org/10.1016/j.palaeo.2012.09.008

Jablonski, D. 2008, Species selection: theory and data. Annu. Rev. Ecol. Evol. Syst. 39, 501–524.

Sheriden, J. A; Bickford, D. 2011, Shrinking body size as an ecological response to climate change. Nat. Clim.

Wright JD, Schaller MF (2013) Evidence for a rapid release of carbon at the Paleocene-Eocene thermal maximum. Proc Natl Acad Sci USA 110(40):15908–15913.

The legacy of the feud between Florentino Ameghino and P. Moreno.

Sin título

Portrait of Florentino Ameghino (1854-1911) by Luis De Servi (1863-1945).

In 1887, Florentino Ameghino, former Assistant Director of the Museo de la Plata, and Francisco P. Moreno, head of the museum, were in a middle of a bitter dispute. The discovery of the phorusrhacid birds played a big role in this story. The feud between Ameghino and Moreno is in many aspects similar to the well-known feud between E.D. Cope and O.C. Marsh, which took place in the United States at roughly the same time.

Florentino Ameghino was born on September 19, 1853. He came from a family of Italian immigrants who settled in 1854 in the town of Lujan, where the extraction and exportation of fossils were a lucrative activity. Throughout his scientific career, he was seconded by his younger brother Carlos Ameghino (1865–1936).  Carlos had been employed by Moreno at the same time as his brother, as “travelling naturalist” for the Museo de La Plata. During his trips, he gathered a remarkable collection of fossil mammals, later described by Florentino. In January 1888, Florentino Ameghino resigned from his position at the Museo de La Plata, and Moreno denied him access to the paleontological collection.  From that moment, and until became head of the Museo Argentino de Ciencias Naturales in Buenos Aires in 1902, the Ameghino brothers continued with their palaeontological exploration, without any permanent official support, but they managed to get the funds to run their paleontological investigations as a private enterprise. For instance, Karl von Zittel subsidized their explorations, receiving in exchange fossils for the collection of the Munich University. Meanwhile Moreno, in order to gain priority over his rivals, published a series of brief reports about the new palaeontological discoveries made by his field researchers.

Francisco Pascacio Moreno (1852-1919). From Wikimedia Commons

Francisco Pascacio Moreno (1852-1919). From Wikimedia Commons

In 1895, the critical financial situation forced Florentino Ameghino to sell his fossil bird collection, in order to support his further work in Patagonia. The collection was purchased by the London Museum by the sum of 350 £ in 1896. When Florentino became director of the Museo Nacional de Buenos Aires in 1902 the selling of fossils ceased, and he started making claims for the return of the museum’s collections. He also proposed that the most remarkable specimens of Patagonian and Pampean fossil faunas be cast and stored in Buenos Aires and La Plata museums to be used in Argentinean schools. The same casts were sent to Museums all over the world and in exchange, Ameghino received casts of the oldest fossil mammals from Africa and the Northern Hemisphere to compare with the Patagonian faunas (Podgorny, 2005). It was a smart way to prevent the sale of the original fossils.


Ameghino, F. 1895. Sobre las aves fosiles de Patagonia. Boletín del Instituto Geografico de Argentina 15:501–602.

Ameghino, F. 1891a. Mamíferos y aves fósiles Argentinos: espécies nuevas: adiciones y correciones. Revista Argentina Historia Natural, 1:240-259.

Eric Buffetaut (2013), Who discovered the Phorusrhacidae? An episode in the history of avian palaeontology, Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution Paleornithological Research 2013.

Moreno, F.P. 1889. Breve reseña de los progresos del Museo La Plata, durante el segundo semestre de 1888. Boletin del Museo La Plata, 3:1-44.

Podgorny, I. 2005. Bones and devices in the constitution of paleontology in Argentina at the end of the nineteenth century. Science in Context 18(2): 249-283



A brief introduction to the stratigraphy of mass extinctions.


The permian triassic boundary at Meishan, China (Photo: Shuzhong Shen).

Extinction is the ultimate fate of all species. The fossil record indicates that more than 95% of all species that ever lived are now extinct. Over the last 3 decades, mass extinction events  have become the subject of increasingly detailed and multidisciplinary investigations. In 1982, Jack Sepkoski and David M. Raup used a simple form of time series analysis at the rank of family to distinguish between background extinction levels and mass extinctions in marine faunas, and identified five major extinction events in Earth’s history: at the end of the Ordovician period, Late Devonian, End Permian, End Triassic and the End Cretaceous. These five events are know as the Big Five. The most recently identified mass extinction occurred during the Middle Permian, about  262 million years ago, and it was first recognised in the marine realm as a turnover among foraminifera, with fusulinaceans among the principal casualties.

A central question in the understanding of mass extinctions is whether the extinction was a sudden or gradual event. This question may be addressed by examining the pattern of last occurrences of fossil species in a stratigraphic section.  Also, the geochemical history recorded in marine sediments preserves a valuable record of environmental change during mass extinctions. However, stratigraphical processes of sediment accumulation could affect the chronology of environmental change. And of course, the Signor–Lipps effect complicates the timing of extinction.

The trilobite Kainops invius, in lateral and ventral view. From Wikimedia Commons

The trilobite Kainops invius, in lateral and ventral view. From Wikimedia Commons

The last occurrences of fossil species generally predate the times of extinction. Based on principles of sequence stratigraphy, marine ecology, and evolution, numerical models of fossil occurrences in stratigraphic sections suggest that the last occurrences of fossil species are controlled by stratigraphic architecture. In some cases, stratigraphical architecture can give the illusion of a double pulse or even a triple pulse of extinction (Holland, 2015).

The Cambrian and Lower Ordovician record involve the abrupt termination of many shallow-water trilobite lineages, a reduction in the number of biofacies across the shelf, and the immigration and origination of new lineages; and in many locations, the extinction is closely associated with an unconformity. With the notable exception of the end-Cretaceous extinction, mass extinction events have similar stratigraphical expressions. In depositional dip settings, they are recorded as a single cluster of last occurrences that is closely associated with a major flooding surface, which in some cases is combined with a sequence-bounding subaerial unconformity. Where depositionally downdip sections are available, such as for the Late Ordovician and the Late Devonian, two clusters of last occurrences are present. They may suggest discrete pulses of extinction, although they are equally consistent with a more prolonged extinction. In the Late Devonian, the faunal changes occur in three separate episodes, with the Taghanic event at the end of the Givetian, the Kellwasser event at the end of Frasnian and the Hangenberg event at the end of the Famennian. Of these, the Kellwasser event is the largest. One of the characteristics of the Kellwasser event is that the extinction was more severe in shallow-water faunas, and the stratigraphical pattern of last occurrences is consistent not only with a pulse of extinction timed with the flooding surface, but also with a more protracted interval of extinction. (Holland et Patzkowsky, 2015)


Holland, S. M., Patzkowsky, M. E. (2015), The stratigraphy of mass extinction. Palaeontology. doi: 10.1111/pala.12188

Bambach, R.K., Knoll, A.H. and Wang, S.C., 2004. Origination, extinction, and mass depletions of marine diversity. Paleobiology, 30, 522–542.

Steve C. Wang, Aaron E. Zimmerman, Brendan S. McVeigh, Philip J. Everson, and Heidi Wong, (2012), Confidence intervals for the duration of a mass extinction, Paleobiology, 38(2), pp. 265–277.

Seth D. Burgess, Samuel Bowring, and Shu-zhong Shen, High-precision timeline for Earth’s most severe extinction, PNAS 2014, doi:10.1073/pnas.1317692111

Wignall, P. B. 2001. Sedimentology of the Triassic–Jurassic boundary beds in Pinhay Bay (Devon, SW England). Proceedings of the Geologists’ Association, 112, 349–360

Owen, Dickens and the ‘invention’ of dinosaurs.

Sir Richard Owen (1804-1892)

Sir Richard Owen (1804-1892)

On 20 February 1824, William Buckland published the first report of a large carnivore animal: the Megalosaurus. He had a piece of a lower jaw, some vertebrae, and fragments of a pelvis, a scapula and hind limbs, probably not all from the same individual. Buckland’s published description was based on specimens in the Ashmolean Museum, in the collection of Gideon Algernon Mantell of Lewes in Sussex and a sacrum donated by Henry Warburton (1784–1858). One year later, the Iguanodon entered in the books of History followed by the description of Hylaeosaurus in 1833. After examined the anatomy of these three genera, Richard Owen recognized that Iguanodon, Megalosaurus, and Hylaeosaurus share several traits that distinguished them from other ancient or living creatures, like their giant size and five fused vertebrae welded to their pelvic girdle. In April 1842, Owen created the “Dinosauria” : “The combination of such characters, some, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of Dinosauria.“(Richard Owen, “Report on British Fossil Reptiles.” Part II. Report of the British Association for the Advancement of Science, Plymouth, England, 1842)

Megalosaurus sacrum with fused vertebrae (from Buckland 1824, pl. 42).

Megalosaurus sacrum with fused vertebrae (from Buckland 1824, pl. 42).

It was an exciting time full of discoveries and the concept of an ancient Earth became part of the public understanding. The study of the Earth was central to the economic and cultural life of the Victorian Society and Literature influenced the pervasiveness of geological thinking. 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. Dickens  also published some of Owen’s work in his periodical, Household Words and All the Year Round.

Owen used his influence with Prince Albert, Queen Victoria’s husband, to propose the financing of the three-dimensional reconstruction of the first known dinosaurs: Megalosaurus, Iguanodon and Hylaeosaurus, for the closure of the first international exposition in modern European history: the Crystal Palace exhibition. About six million people visited the Great Exhibition. Megalosaurus became so popular that is mentioned in Charles Dickens’s novel Bleak House: “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.”  It was the first appearance of a dinosaur in popular literature.


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).

Moody, R. T. J., Buffetaut, E., Naish, D.& Martill, D. M. (eds) Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications, 343, 335–360

RUPKE, N. A. (2009): Richard Owen. Biology without Darwin. University of Chicago Press: 344

Torrens, H. S. (2014), The Isle of Wight and its crucial role in the ‘invention’ of dinosaurs. Biological Journal of the Linnean Society, 113: 664–676. doi: 10.1111/bij.12341