”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.

Haeckel_Trochilidae

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.

 

References:

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.

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Climate Change and the Evolution of Mammals.

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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

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.

References:

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.

References:

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.

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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)

References:

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