Ernst Stromer and the lost Dinosaurs of Egypt.

 Ernst Freiherr Stromer von Reichenbach. From Wikimedia Commons

Ernst Freiherr Stromer von Reichenbach. From Wikimedia Commons

Ernst Freiherr Stromer von Reichenbach was born in Germany on June 12, 1870. In 1893, he began to study geology and paleontology at the University of Munich and wrote his thesis about the geology of the German colonies in Africa, under the direction of Karl Alfred von Zittel.

He later became a vertebrate paleontologist at the Paläontologisches Museum in Munich and an expert on fossil fish and mammals. But I was not until 1901 that he travelled to Africa, more specifically to El Fayum, a fossiliferous location discovered by George August Schweinfurth, a German botanist. The place contains fossil mammals from the Eocene-Oligocene boundary. Supported by the Bavarian Academy of Sciences and Humanities (Bayerische Akademie der Wissenschaften), he conducted a second expedition in 1902.

Bahariya Oasis.

Bahariya Oasis.

In 1910, E. Stromer went to his  third paleontological expedition to Egypt. He arrived to Alexandria on November 7. He was initially looking for early mammals and planned visit the area of Bahariya, in the Western Desert, which has sediments from the Cretaceous era. But an expedition to the Western Desert needed the permission by the English and French colonial authorities and of course the Egyptian authorities. Although diplomatic relations with Germany were rapidly deteriorating , Stromer managed to get the permissions.

He arrived to the Bahariya Oasis on January 11, 1911. After facing some difficulties during the journey, on January 17 he began to explore the area of Gebel el Dist, and at the bottom of the Bahariya Depression, Stromer found  the remains of four immense and entirely new dinosaurs ( Aegyptosaurus, Bahariasaurus, Carcharodontosaurus and Spinosaurus aegyptiacus), along with dozens of other unique specimens.

“Illustrations of the vertebrate “sail” bones of Spinosaurus that appeared in one of Stromer’s monographs. From Wikimedia Commons.

With the help of Richard Markgraf (1856-1916), Stromer excavated in three years numerous remains of dinosaurs, snakes, turtles, marine reptiles and crocodiles. Unfortunately, due to political tensions  before and after World War I, many of this fossils were damaged after being inspected by colonial authorities and not arrived to Munich until 1922. The shipping from El Cairo was paid by the Swiss paleontologist Bernhard Peyer (1885-1963), a former student and friend of Stromer.

The most famous of all Stromer’s discoveries was the Spinosaurus. This gigantic predator is estimated to have been about 50 to 57 feet (15 to 17 m) with unusually long spines on its back that probably formed a large, sail-like structure.

This is the only photographic proof of German researcher Ernst Stromer's discovery of Spinosaurus. Image from the Washington University in St. Louis

This is the only photographic proof of German researcher Ernst Stromer’s discovery of Spinosaurus. Image from the Washington University in St. Louis

During the World War II, Stromer tried to convince Karl Beurlen -a young nazi paleontologist who was in charge of the collection- that he had to move the fossils to a safer place, but he refused to do it. Finally, on April 24, 1944, a British Royal Air Force raid bombed the museum and incinerated its collections. Of course, that was not an isolated occurrence. Between 1940 and 1944, several dinosaur fossils were destroyed in World War II battles.

Stromer was an aristocrat (“Freiherr” in his name roughly equals “baron” in English) who refused to join the Nazi, but Stromer’s defiance cost him dearly: all of his sons were sent to the German army. Two of them died in combat and one was captured and imprisoned in the Soviet Union for several years.

In 2000, a new paleontological expedition went to Bahariya and recovered the first dinosaur’s remains since the time of Stromer and Markgraf. Among the new findings is the sauropod Paralititan stromeri (named in Stromer’s honor).

References:

Sanz, José Luis,  Cazadores de Dragones, Editorial Ariel, 2007

Holmes, Thom, Last of the Dinosaurs: The Cretaceous Period, Infobase Publishing, 2008.

Advertisements

Pollen analysis and the science of climate change.

Example of fossil pollen grains from Eocene of Huadian , Jilin, China.

Example of fossil pollen grains from Eocene of Huadian , Jilin, China.

Pollen grains are the carriers of the male gametes or their progenitor cell, in higher plants. They also are important tools for paleoclimatic reconstruction.  They reflects the ecology of their parent plants and their habitats and provide a continuous record of their evolutionary history.

Like spores, pollen grains possess a wall highly resistant to microbial attack. This wall comprises two layers,  the outer, highly resistant exine mostly composed by sporopollenin, a biopolymer considered “the most resistant organic material known”, and the inner intine that surrounds the cytoplasm. The morphology of pollen grains is diverse. 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).

Arabis pollen has three colpi and prominent surface structure. From Wikimedia Commons

Arabis pollen has three colpi and prominent surface structure. From Wikimedia Commons

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 are filtered by differential dispersal in the air and in the water. For instance, large miospores, pollen grains and megaspores will tend to settle out in rivers, estuaries, deltas or shallow shelf areas, whereas small miospores and pollen grains may settle out in outer shelf and oceanic conditions. The differences in pollen productivity and dispersion rates pose a significant problem for palaeoclimatic reconstruction because the relative abundances of pollen grains in a deposit cannot be directly interpreted in terms of species abundance in the study area. Another difficult is that spores and pollen may suffer several cycles of reworking and redeposition, leading to some confusion in the fossil record.

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 Wikimedia Commons

Gunnar Erdtman, a Swedish botanist, published  in 1921,  his thesis about pollen as a tool for study the Quaternary vegetation and climate change. He was the first to suggest this application for fossil pollen.

Pollen analysis involves the quantitative examination of spores and pollen at successive horizons through a core, specially in lake, marsh or delta sediments, especially in Quaternary sediments where the parent plants are well known. This provide information on regional changes in vegetation through time, and it’s also a valuable tool for archaeologists because gives clues about man’s early environment and his effect upon it.

In a recent study, applied to the Crisis in the Late Bronce Age (LBA) in Cyprus and Syria, the pollen record reveals the presence of plants adapted to drier weather, which indicates a decrease in rainfall. Researchers suggest that this drought lasted about three hundred years causing crop failures, dearth and famine, and forcing regional human migrations at the end of the LBA in the Eastern Mediterranean and southwest Asia.

References:

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

Traverse, A. (1988), Paleopalynology. Unwin Hyman

Kaniewski D, Van Campo E, Guiot J, Le Burel S, Otto T, et al. (2013), Environmental Roots of the Late Bronze Age Crisis. PLoS ONE 8(8): e71004.doi:10.1371/journal.pone.0071004

Ernst Haeckel, the scientist as an artist.

Ernst Haeckel, 1860. From Wikimedia Commons.

Ernst Haeckel, 1860. From Wikimedia Commons.

Ernst Haeckel was born on February 16, 1834, in Potsdam, Prussia. He grew up in Merseburg, where his father was a government official. He studied medicine to please his family, at the University of Berlin and graduated in 1857. But his real passion was biology, something he discovered while he was still a medicine student and his professor Johannes Müller, physiologist and anatomist, took him on a summer expedition to observe small sea creatures off the coast of Heligoland in the North Sea.

In 1859, when Haeckel was 25, travelled to Italy with the help of his parents. Haeckel spent some time in Napoli, exploring and discovering his talent as an artist. Then he went to Messina, where began to study radiolarians. Like Goethe and Humboldt, his science was influenced by deep his aesthetic aspirations and those little exquisite creatures, satisfied both.

Ernst Haeckel's ''Kunstformen der Natur'' (1904), showing Radiolarians of the order Stephoidea. From Wikimedia Commons.

Ernst Haeckel’s ”Kunstformen der Natur” (1904), showing Radiolarians of the order Stephoidea. From Wikimedia Commons.

In 1864, young Haeckel sent to Darwin, two folio volumes on radiolarians. The gothic beauty of these drawings impressed Darwin. He wrote to Haeckel that “were the most magnificent works which I have ever seen, and I am proud to possess a copy from the author“.

Haeckel became the most famous champion of Darwinism in Germany and he was so popular that, previous to the First World War, more people around the world learned about the evolutionary theory through his work “Natürliche Schöpfungsgeschichte” (The History of Creation: Or the Development of the Earth and its Inhabitants by the Action of Natural Causes) than from any other source.

Radiolaria illustration from the Challenger Expedition 1873–76. From Wikimedia Commons.

Radiolaria illustration from the Challenger Expedition 1873–76. From Wikimedia Commons.

He was one of the first to state that humans evolved from apes and life evolved from non-living matter. He claimed that evidence of human evolution could be found in the Dutch East Indies (now Indonesia).  Eugene Dubois, inspired by Haeckel’s ideas, went to Indonesia and found the fossil remains of a hominid,  later reclassified as Homo erectus.

He also wrote more than twenty monographs about systematic biology and evolutionary history, among them his studies of radiolarians, medusae and sponges are the most popular. He formulated the concept of  ”ecology” and coined the terms of “protist”,  “ontogeny”, “phylum”, “phylogeny”,  “heterochrony”, and “monera”.

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.

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. His master work “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.

Ernst Haeckel died on August 9, 1919 in Germany at the age of 85.

References:

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

Brief Introduction to Patagonian theropods

Skull of Giganotosaurus, MACN (]Argentinean Museum of Natural Sciences)

Skull of Giganotosaurus, MACN (Argentinean Museum of Natural Sciences)

The Cretaceous beds of Patagonia have yielded the most comprehensive record of Cretaceous non-avian theropods  from Southern Hemisphere, which includes at least five main theropod lineages: Abelisauroidea, Carcharodontosauridae, Megaraptora, Alvarezsauridae, and Unenlagiidae. These record facilitates the understanding of the origin, evolution, and radiation of theropods from Gondwana. The first remains of dinosaurs were found near Neuquen city by an officer army in 1882 and were sent to Florentino Ameghino, the “founder father” of Argentinian paleontology.

Genyodectes holotype. From Wikimedia Commons.

Genyodectes holotype. From Wikimedia Commons.

By the end of  the 1880s, Santiago Roth collected some dinosaur remains from Chubut and  sent them to Richard Lydekker and Arthur Smith Woodward. In 1901, A. Smith Woodward described Genyodectes, based on fragmentary skull bones, including portions of both maxillas, premaxillae,  parts of the supradentaries, and some teeth. Genyodectes remained as the most completely known  theropod from South American until the 1970s. In 2004, O. Rauhut concluded that Genyodectes is more closely related to Ceratosaurus than the more derived abelisaurs.

Skull of  Carnotaurus sastrei, from MACN.

Skull of Carnotaurus sastrei, from MACN.

The  Abelisauroidea reached a great taxonomic diversity and their fossils have been recovered in Argentina, Brasil, Madagascar, India, Morocco, Lybia and France. The group has been divided in two main branches: the Noasauridae which includes the small-sized abelisauroids, and the Abelisauridae which comprises medium to large-sized animals, like the popular Carnotaurus sastrei.

The group exhibits strongly reduced forelimbs and hands, stout hindlimbs, with a proportionally robust and short femur and tibia. It has been suggested that from the Cenomanian to the Maastrichtian, most South American abelisaurids may have been isolated from other Gondwanan relatives.

The Carcharodontosauridae includes the largest land predators in the early and middle Cretaceous of Gondwana, like the popular, Giganotosaurus carolinii. The group evolved large skulls surpassing the length of the largest skull of Tyrannosaurus rex.  Another common trait is the fusion of cranial bones.

Bicentenaria Argentina. MACN

Bicentenaria Argentina. MACN

The Coelurosauria is also a diverse clade. Bicentenaria argentina is a very basal coelurosaur, medium sized with elongate and gracile hindlimb bones. Another basal coelurosaur is Aniksosaurus darwini.

Megaraptora  is a clade represented by Megaraptor, Orkoraptor and Aerosteon. It has been suggested that megaraptorans were basal coelurosaurs that shared the role of top predators with abelisauroids and carcharodontosauroids.

The Alvarezsauridae is a group of highly derived theropods. The group exhibits, among other features,   a lightly built skull bearing numerous small teeth restricted to the anterior portion of the snout, robust humerus with a proximally projected inner tubercle, a robust ulna and a hand with very robust digit I carrying a large and stout claw, and keeled sternum.

Unenlagia comahuensis by Nobu Tamura. From Wikimedia Commons

Unenlagia comahuensis by Nobu Tamura. From Wikimedia Commons

South American paravians are included within the clade Unenlagiidae: Buitreraptor gonzalezorum, Unenlagia comahuensis, Unenlagia paynemili and Austroraptor cabazai, all recovered from the Upper Cretaceous of Patagonia, Argentina.

The fossil record shows that the macroevolutionary patterns observed in Gondwana at the Late Cretaceous differ from the records from Laurasia, but both show a common  macroevolutionary pattern during post-Coniacian times.

References:

Novas, F.E., et al., Evolution of the carnivorous dinosaurs during the Cretaceous: The evidence from Patagonia, Cretaceous Research (2013), http://dx.doi.org/10.1016/j.cretres.2013.04.001