Sir Arthur Conan Doyle and the Pterosaurs.

Arthur Ignatius Conan Doyle (1859-1930). From Wikimedia Commons

Sir Arthur Conan Doyle began to write The Lost World in 1911. One year later it was published in book form by Hoddar and Stoughton. By that time he already was one of the most popular author around the globe, thanks to his most iconic creation, Sherlock Holmes. It’s well documented that Conan Doyle had a great interest in paleontology. He attended several talks on fossils and among his friends were Ray Lankester, Charles Dawson and Arthur Smith Woodward. He was part of several palaeontological digs  and also visited the now infamous Piltdown Man excavations in Sussex.

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

Pterosaurs are an extinct monophyletic clade of ornithodiran archosauromorph reptiles from the Late Triassic to Late Cretaceous. Pterodactylus is a genus of pterosaurs, popularly known as pterodactyls. The first pterosaur discovered was identified in 1784 by Italian scientist Cosimo Collini but was Georges Cuvier who coined the term “Pterodactyle” in 1809 after the discovery of a fossil skeleton in Bavaria, Germany. Although, the first published depiction appears to be in the watercolour Duria Antiqior by Henry de la Beche, where several pterosaurs are seen flitting over a scene of ichthyosaur and plesiosaur, representing the Liassic Sea based on fossils found by Mary Anning. Richard Owen’s (1870) also included a short chapter on pterosaurs in his classic text book “Palaeontology”.

But probably, one of the most influential works in Doyle’s novel was “Extinct Animals” by Ray Lankester. The book was published in 1905,  with a short chapter dedicated to pterosaurs where he emphasized the shape of the wings and supported by detailed illustrations.

H. Rountree’s artwork from The Lost World

The Lost World, has much in common with ”Journey to the Centre of the Earth” by Jules Verne. This book was published in France in 1874 and it was Verne, who first introduced Pterosaurs into popular fiction. But there’s a profound contrast between the treatment that both writers gave to Pterosaurs. In “Journey to the Centre of the Earth”,  the pterosaurs had a small presence while in “The Lost World”,  pterosaurs are central figures.

At the beginning of the novel, Professor George Edward Challenger claims to have captured and subsequently lost, a living specimen in South America. After being ridiculed for years, he invites E. Malone, a reporter for the Daily Gazette, Professor Summerlee and Lord John Roxton, an adventurer who knows the Amazon to join him to a trip to South America and prove his story. Later, the crew were attacked by pterodactyls in a swamp. Doyle compares the place with one of the Seven Circles of Dante and described as followed: “The place was a rookery of pterodactyls. There were hundreds of them congregated within view. All the bottom area round the water-edge was alive with their young ones, and with hideous mothers brooding upon their leathery, yellowish eggs”

Doyle completes the scenes by describing the males: “Their huge, membranous wings were closed by folding their fore-arms, so that they sat like gigantic old women, wrapped in hideous web-coloured shawls, and with their ferocious heads protruding above them. Large and small, not less than a thousand of these filthy creatures lay in the hollow before us”

Later, the protagonists discussed over the correct identification of the genus: Are they Pterodactylus or Dimorphodon? Throughout the story the pterodactyls appear and reappear,  attacking them and stealing their food. Finally, one is captured and brought back to London and it’s presented to an audience at the Zoological Institute, but the creature makes its escape through an open window. No other animal receives such continued treatment throughout the book, or is illustrated in such detail. This could indicates that Doyle was fascinated by pterodactyls.

The Lost World novel has been so immensely popular that it has had a lasting effect, and has contributed significantly to the fascination with dinosaurs and pterodactyls. Even more, the first full-length animated science fiction film was based on Conan Doyle’s novel. This is a trailer of that movie.

In 1994, Arthurdactylus a genus of pterodactyloid pterosaur from the Lower Cretaceous  of Brazil was named in honor of Arthur Conan Doyle.

 

References:

Conan Doyle, A., The Lost World & Other Stories, Wordsworth Editions (1995)

Martill, D. M, and Pointon, Tony, Dr Arthur Conan Doyle’s contribution to the popularity of pterodactyls, Geological Society, London, Special Publications, 375, 2013, doi:10.1144/SP375.19

AN INTRODUCTION TO FORAMINIFERA

The Foraminiferida are an important group of single celled protozoa.  There are an estimated 8,000 species living in the world’s oceans today, among  the sea floor and the marine plankton and comprise over 55% of Arctic biomass and over 90% of deep sea biomass.

The first ocurrence of forams is from the Early Cambrian and the range extend to the present day. A recent study suggest that the rise of the forams coincides with the demise of stromatolites. Those earliest forms had organic test walls or  simple agglutinated tubes and were benthics.

The Order Foraminiferida (informally foraminifera) possesses a shell (test) of different composition, and granuloreticulose pseudopodia (extensions of ectoplasm with grains o tiny particles of various composition).

Benthic foraminiferid in cross-section.

At the cellular level, the cytoplasm is differentiated into an outer layer of clear ectoplasm and an inner layer of darker endoplasm. The ectoplasm forms a mobile film around the test with numerous, granuloreticulose pseudopodia whose form is ever changing. The endoplasm often contains diatoms and dinoflagellates as symbionts.

Living species of foraminifera present various types of reproductive strategies, with alternation of sexual and asexual generation. The size range is from about 100 micrometers to almost 20 centimeters long. They also use a great variety of feeding mechanisms, as evidenced by the great variety of test morphologies that exhibit.

The test consists of one or multiple chambers interconnected by an opening, the foramen. The composition and structure of the test wall is very important for the classification of the group. There are three basic types of wall composition: organic, agglutinated and secreted calcium carbonate.

Allogromia laticollaris

The suborder Allogromiina comprises all the organic-walled forms, composed  by a proteinaceous mucopolysaccharide.

Textularia agglutinans

The suborder Textulariina encompasses forms with agglutinated tests composed of randomly accumulated grains or grains selected by specific gravity, shape or size.

Quinqueloculina seminulum.

Secreted test foraminifera are subdivided into three major groups. First, the suborder Fusulinina, with microgranular tests.  Second, the suborder Miliolina with porcelaneous test.

Globigerina bulloides.

In third place, the hyaline test  may be of calcite (which encompasses the suborders Spirillinina, Globigerinina, Rotaliina), or aragonite (Involutinina, Robertinina).

The external surface of the test may bear spines, keels, rugae, granules or a reticulate sculpture.

The morphology of foraminifera tests varies enormously, but in terms of classification two features are important: chamber arrangement and aperture style. The tests of many primitive foraminifera are unilocular, although test form varies greatly. Unilocular tests may be globose, tubular, branched, radiated or irregular. And in the case of the chambers of multilocular forms they could be globular, tubular, compressed lunate and wedge-shaped.

Two types of chamber arrangement: single chambered and uniserial.

In the Lower Palaeozoic, the tests were mainly agglutinated. By the late Devonian, septate periodic growth evolved and Foraminifera with hard test became more common. In the early Carboniferous first appeared the miliolids, followed in the Mesozoic by the appearance and radiation of the rotalinids and the textularinids. Also planktic forms appeared in the Mid Jurassic in the strata of the northern margin of Tethys and epicontinental basins of Europe. During the Palaeocene appeared the planktic globigerinids and globorotalids. The diversity of planktic forms has also generally declined since the end of the Cretaceous with brief increases during the warm climatic periods of the Eocene and Miocene.

In 1835, Dujardin recognised foraminifera as protozoa and shortly afterwards d’Orbigny produced the first classification. Early data on deep-sea benthic foraminifera (and on other deep-sea groups) were collected on the 1872-1876 Challenger Expedition and E. Hackel also included forams in his master work “Kunstformen der Natur”.

Foraminifera have been widely utilised for biostratigraphy. They also have a wide  environmental range and changes in the composition of foraminiferal assemblages could be used to track changes in the circulation of water masses and in sea-water depth. They are particularly important in studies of Mesozoic to Quaternary climate history because isotopes within their CaCO3 tests record changes in temperature and ocean chemistry.

References:

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

Gooday, Andrew J., Rothe, Nina and Pearce, Richard B. (2013) New and poorly known benthic foraminifera (Protista, Rhizaria) inhabiting the shells of planktonic foraminifera on the bathyal Mid-Atlantic Ridge,  Marine Biology Research, 9, (5-6), 447-461 (doi:10.1080/17451000.2012.750365).

Bernhard JM, Edgcomb VP, Visscher PT, McIntyre-Wressnig A, Summons RE, Bouxsein ML, Louis L, Jeglinski M., Insights into foraminiferal influences on  of microbialites at Highborne Cay, Bahamas, PNAS June 11, 2013 vol. 110 no. 24 9830-9834.

An introduction to diatoms.

Diatoms are almost ubiquitous. They live in aquatic environments, soils, ice, attached to trees or anywhere with humidity and their remains accumulates forming diatomite, a type of soft sedimentary rock.
They are the dominant marine primary producers in the oceans and play a key role in the carbon cycle and in the removal of biogenic silica from surface waters.

Diatoms are unicellular algae with golden-brown photosynthetic pigments. They have a siliceous skeleton known as frustule that comprise two valves, one overlaps the other like the two pieces of a petri dish. The frustule is ornamented with pores, processes, spines, hyaline areas and other features The size range is between 1 to 2000 μm in length.

Diagrammatic sections of a frustule. From UCL.

They belong to the Division Chrysophyta, Class Bacillariophyceae and are divided in two Orders: The Centrales or Biddulphiales and the Pennales or Bacillariales. The Pennales or pennate diatoms have frustules that are elliptical or rectangular in valve view, with sculpture that is bilaterally symmetrical about a central line while the Centrales are characterized by frustules which are circular, triangular or quadrate in valve view and rectangular or ovate in girdle view.

Diatoms could be single or could form colonies. The cell has two or more golden-brown photosynthetic chloroplasts, a central vacuole, a large central diploid nucleus. Diatoms also store oils rather than starch and lacks of flagella or pseudopodia.

The first record of diatom frustules are centric forms from the Early Jurassic although very few remains are known before the Late Cretaceous, they were moderately affected by the massive extinction at the end of the Cretaceous.

Crossophialus gyroscolus and C. glabrus from the Upper Cretaceous of Antarctica. Image from the Ocean Drilling Program.

Centric diatoms had a major radiation in the Paleocene. Pennate diatoms also appeared during the Paleocene. The provincialism among diatoms increased in the latest Miocene and during the Pleistocene, diatom assemblages start to closely resemble modern ones.

Azpeitia tabularis (Miocene to Recent) and Fragilariopsis ritscheri (Pliocene to Recent). From UCL

During the 19th century, Ehrenberg, Grunow, Schmid and others studied and made great illustrations of diatoms, but was E. Hackel who created the most beautiful and artistic representations of diatoms in his work “Kunstformen der Natur”.

Living diatoms are very sensitive to parameters like salinity, oxigenation and other physical and chemical conditions, so they provide a valuable tool for studies of modern water quality and for the reconstruction of past environments, particularly for evidence of climatic cooling and changing sedimentation rates in the Arctic and Antarctic oceans. Also the evolutionary history of diatoms has been punctuated by several floristic turnovers which makes diatoms great tools for biostratigraphic correlations.

References:

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

Barron, J.A. (2003). Appearance and extinction of planktonic diatoms during the past 18 m.y. in the Pacific and Southern oceans. “Diatom Research” 18, 203-224

The beauty of radiolarians.

Radiolarians are single-celled protist marine organisms that generate unique and intricately detailed glass-like exoskeletons. The size range varies between 20 and 300 microns, in the case of solitary forms and up to 3 m, in the colonial forms.

They belong to the Phyllum Protista, Subphylum Sarcodina, Class Actinopoda, Subclass Radiolaria and include two Superorders: The Phaedaria and The Polycystina. The Phaedaria have skeletons composed of hollow silica bars joined by organic material and are not commonly preserved in the fossil record, meanwhile the Polycystina have skeletons of pure silica and are more commonly preserved in the fossil record. Also, the Polycystina are divided into two suborders: the Spumellaria and the Nassellaria.

Diagrammatic cross-section of a radiolarian. Image from UCL.

At the cellular level there’s an inner capsule that divides the cytoplasm in two different units: the endoplasm -which is contained by the capsule-, and the surrounding ectoplasm that often contains symbiotic algae and on the surface of the ectoplasm there’s a layer of ray-like axopodia and rhizopodia.

The skeleton is formed by bars (elongated elements and connected at both ends), spines (elongated elements, attached at only one end) or perforated plates. The structure of the skeleton wall could be spongy, lattice or perforated. Symmetry is the element that allows characterization of the skeleton. This may be spherical (or a derivative form) or axial. The skeletons with spherically symmetry may include intra and extracapsular concentric spheres,  with internal spiral structure, biconvex discs, or triradiate plates. In case of  skeletons with axial symmetry, they have one or more segments arranged along an axis. The Spumellaria shows a spheric symmetry and the Nassellaria have axial symmetry.

Basic morphological features of a nassellarian radiolarian. From UCL.

Radiolaria were among the earliest eukaryotes. The first recorded occurrences are from the end of the Precambrian and the geological record is extended to Recent.  Early radiolarians belong to the Orden Spumellaria and the first members of the Orden Nassellaria appeared  at the end of Carboniferous.

Because the variation of skeletons through time, radiolarians are very useful as biostratigraphic tools. They have also been used as paleoclimatic indicators of paleotemperatures, paleogeography and tectonic changes.

Ehrenberg made a series of special monographs from 1838 to 1875 and named the group Polycystina. In 1855, Johann Muller suggested the name Radiolaria. But was Ernst Haeckel who made the first complete  classificatory system for the Radiolaria and produced finely detailed drawings of them in his book: “Die Radiolarien” in 1862.

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

Haeckel was a man of science and an aesthete. He published his master work “Kunstformen der Natur” (Art Forms of Nature)  in 1904 and helped to popularize radiolarians among the microscopists of the Victorian Era.

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

In 2004, David Lebrun wrote and directed a documentary about the understanding of marine creatures in 19th century with special emphasis on Ernst Haeckel and his fascination with radiolarians.

References:

Boltovskoy, D. 1998. Classification and Distribution of South Atlantic Recent Polycystine Radiolaria. Paleontologica Electronica, 1(2).

M.S. Afanasieva, E.O. Amon, Yu.V. Agarkov and D.S Boltovskoy. Radiolarians in the geological annals. Paleontological Journal. 2005. Vol. 39. No. 3.

Links:

Ernst Haeckel: Die Radiolarien  (RHIZOPODA RADIARIA) Berlin, 1862, http://www.biologie.uni-hamburg.de/b-online/radio/