What Bugged the Dinosaurs?

Fig.1. Cimex lectularius, the terrible bed bug.

"Beware the Jabberwock, my son!
The jaws that bite, the claws that catch!
Beware the Jubjub bird, and shun
The frumious Bandersnatch! "
Jabberwocky, by Lewis Carroll (1832-1898)

Insects entombed in amber were noted since antiquity; however a first naturalistic research and binomial description occurred only in 1779 by Marcus Elieser Bloch (1723-1799), just one year after Linne´s death. Bolch studied copal, a fossil tree resin younger then classic amber, ranging only some million years in age.
Most of early palaeoentmological work dealing with fossils in amber or fine-grained sediments was not carried out by professional entomologists, but by geologists, botanist and insect collectors, considering the incredible diversity of insects (925.000 named species until now) an exceptional self-confidence, resulting however often in a chaotic taxonomy, incorrect descriptions or depictions. But it would be unfair to minimize the efforts of these pioneers, they acted in best intent.
With the beginning of the 20th century this general approach became replaced by specific research of professional entomologists.

Insects are the most successful multicellular animal group on earth today, and there is no reason to assume that in the geological past the situation was different.
Amber so provides us with an unique window in this past, and show the diversity and various behaviour that insects evolved over time.

Diverse recent organisms make a living by nourishing on blood, most notable the vampire bats and leeches, even some human cultures, especially the Masai of Kenia, have discovered fresh blood as valuable food, but non of these groups is so successful in the habit to suck blood as the insects.
Not all insects that bites need blood to feed, some species use blood only in certain periods of their development, for example as protein source for egg production. Some insects are generalists and will attack fishes, amphibians, reptiles, birds and mammals, other are more specialized and prefer single groups or species.
Insects, despite the common claim, don't bite, but saw or cut out our skin. Mosquitoes then punctuate direct a blood vessel, and suck the blood (capillary feeders). Other insects group, like blackflies, biting midges, sand flies, and horseflies lacerate the blood vessels, and lick the blood that accumulates in the wound (pool-feeders).

The insect record is a very old one; fossils are known since the Carboniferous, however in part very fragmentary, most modern groups are known only with the beginning of the Triassic or Cretaceous, and groups that today feed on blood are known mostly since the Cretaceous.
Bloodsucking insects from include different insects groups, however mainly dominated by the "flies" (Diptera) as snipe flies (Rhagionidae), athericid flies (Athericidae), blackflies (Simuliidae), biting midges (Ceratopogonids), Sand flies (Phlebotominae) and horse flies (Tabanidae).
Fleas (Siphonaptera) and lice (Phthiraptera) are the second largest group of obligatory blood feeders, and finally also some bugs (Heteroptera) have evolved a taste for blood.
Even if there is no direct evidence that the ancestors of these insects feed on dinosaurs, like a palae-flea fossilised on a dinosaur, the contemporaneity of these groups and dinosaurs makes it highly probable that the insects did benefit from the availability of such large blood packs.
The skin of the dinosaurs comprised various dimensions and patterns of scales or even scutes, some showed scales perfectly fitting each to another, on others the scales or tubercle were embedded in the thin skin, and finally some dinosaurs were also covered by bristles, filaments, proto-feathers and feathers. These various categories however do not exclude each and another, some species possessed body parts covered by classic reptilian epidermis and some parts were covered by feathers.
In every case the skin did not provided an impenetrable wall against all sorts of bloodsucking organisms.

Mosquitoes (Culicidae) are the most familiar group of the blood sucking insect, however they are quite rare in the fossil record and only single specimens confirm their presence during the Cretaceous. Most of the recent forms are opportunists, they will attack whatever host is available, even if preferring mammals and birds, but from 5 genera it is known that they feed also on lizards.

Biting midges (Ceratopogonidae) resemble a tiny version of mosquitoes, in most cases their attack is not noted, only after their dinner a fastidious itchiness remembers their presence. This group is commonly found in Cretaceous amber, and it is probable that they in the past also targeted dinosaurs. Ceratopogonids today are pool feeders, they will attack all sorts of vertebrates and concentrate their effort on regions of a body were blood vessels are easily approachable, like the area surrounding the eye or joints, were scales are smaller or the skin thinner.

Blackflies (Simuliidae) are tiny insects like the biting midges; however they are capable to travel for long periods and can come in gigantic swarms. It seems that large quantities of these insects are capable to weakening and even kill large mammals by the suffered loss of blood.
Fossil remains occur during the Jurassic and Cretaceous in Europe, Australia, Asia, and North America, modern forms are not known to feed on reptiles, but they feed on birds.

Sand flies (Phlebotominae) are probably one of the earliest groups of flies in which some species evolved the ability to suck blood; they switched from nibbling on plants to obtain liquids to use animal wounds during the Jurassic and evolved in the Cretaceous the habit to actively gain blood. Most of them today are general feeders, feeding on all sorts of vertebrates, some species however prefer lizards and snakes, and have no problem to reach the soft skin under the overlapping scales.

Horse-flies and deer-flies of the family Tabanidae were widespread throughout the Cretaceous and today are strong, persistent flies, and appropriately feared as blood pool-feeders on both warm- and cold-blooded animals.
Their "bite" is nasty and often where the insect feed a painful wheal develops. Today at least four species of horseflies are known to prey on crocodiles and anacondas in the Amazon, also turtles and birds can not escape their attacks.

Fleas (Siphonaptera) and lice (Phthiraptera) today thrive under the protection of hairs and feathers on both mammals and birds, and it seems reasonable to assume that they or similar organisms could also accept feathered dinosaurs as habitat. In case of reptilian skinned dinosaurs, it is interesting to note that modern fleas try to avoid reptiles as hosts, probably by the lack of shelter offered by the scales.

Fleas and flea-like insects, like Strashila, have in fact been described from Mesozoic sediments. A robust beak indicated that Strashila may have sucked blood, and claws on the well developed hind legs might have been used to grip feathers or bristles.

Fig.2. Another bizarre, apparently ectoparasitic mecopteroid, Strashila incredibilis, reconstructed from the part and counterpart specimen from the Late Jurassic of eastern Siberia. The huge hind legs were probably used for grasping onto its host. The lobes on the abdomen are an enigma; body length 6 mm (GRIMALDI & ENGEL 2005).

Another Mesozoic flea-like insect (it is tentatively attributed to Mecoptera, group related to true fleas), is the large-bodied Saurophthirus longipes, the prolonged proboscis, extended claws, and long legs have been considered modifications for parasitic behaviour on pterosaur wings or to grasp the border of large dinosaur scales.

Lice are highly specific parasites of mammals and birds, and are placed in two categories, the biting (Mallophaga) and sucking (Anoplura) types. The latter all feed on mammalian blood, while the biting forms, thought to be more "primitive" and older then the sucking forms, feed on feathers, hair, skin and blood.
Fossil lice are rare, from the Cretaceous of Transbaikalia the species Saurodectes is known, a contemporary of dinosaurs and pterosaurs, and possibly feeding on them.

Fig.3. A large Mesozoic louse? Saurodectes vrsanskyi, photo and reconstruction, from the Early Cretaceous of Baissa, Siberia (ca. 140 Ma); body length 17 mm (GRIMALDI & ENGEL 2005).

Blood sucking insects represent today a particular danger for men and animals.
Despite the possibility to become exsanguinated by billions and billions of tiny flies, the true danger coming from insects is that they are acting as highly movable vectors of pathogens. Research on blood sucking insects conserved in amber showed that many of them carry microbes, resembling modern pathogens that cause Leishmania and Malaria, and also small invertebrates and parasites like nematodes.
It is not clear how much these insects contributed to the ecology of dinosaurs, but surely, as today, they played an important role.

Bibliography:

BREHM, A.E. (1892): Insekten, Tausendfüßer und Spinnen. Brehms Tierleben Bd.9. Ernst Ludwig Taschenberg.
GRIMALDI, D. A. & ENGEL, M. S. (2005): Evolution of the Insects. Cambridge University Press: 755
POINAR, G. & POINAR, R. (2007): What Bugged the Dinosaurs? Insects, Disease, and Death in the Cretaceous. Princeton University Press: 296
RASNITSYN, A.P. & QUICKE, D.L.J. (eds.) (2002): History of insects. Kluwer Academic Press: 517

Kangaroos and geologists: The first geological exploration of Australia

It was one of the most ambitious scientific expeditions of all times, the "Geographe" and "Naturaliste" were intended to explore the geology, botany, zoology and anthropology of the distant and largely unknown continent of Hollandia Nova, sometimes referred also as the mythical Terres Australes - today known as Australia.

Despite the discoveries of various previously unknown species, profound insights of the geological past and even a glimpse of evolution, the expedition under the command of Captain Nicolas Baudin today is almost forgotten.

In the year 1606 the Dutchman Willem Janszoon, captain sailing for the powerfull Dutch East India Company landed as first European on the Australian continent; however he and following sailors in the next 30 years assumed that they had discovered an ulterior part of the island of New Guinea. In 1642 the Dutchman Abel Tasman begun the search for the mythical southern continent, the "Terra Australis", and circumnavigated the Australian continent until arriving to the Van-Diemen´s-Land, island that later (1853) would bear his name and is known today as Tasmania.
From 1750 to 1800 French and English expeditions begun to explore the Indian - and the Pacific Ocean, in 1770 captain James Cook mapped the eastern coast of Australia and take possession of the land for the British Empire.
The French dictator Napoleon Bonaparte hoped to conquer some colonies in over sea, and so in 1800 approved a plan for an expedition to the distant continent of Australia.

In the morning of the 19. October 1800 two ships - the "Geographe" and the "Naturaliste" - left the harbour of Le Havre behind, for an expedition that would lead them to the opposite face of the globe.
On board were, under the commandment of Captain Nicolas Baudin (1754-1803), 22 naturalists, 5 zoologists, 3 botanists, geographers, astronomers, artists, gardeners and 2 mineralogists - Louis Depuch (1774-1803) and Charles Bailly (1777-1844), 218 members of the marine and 11 stowaways. In the last moment also the young zoologist, and trained palaeontologist, Francois Auguste Peron (1775-1810), student of the great Cuvier in Paris, joined the expedition.
The geological observations made by Depuch, who will die in the last part of the voyage, are known from various reports to Baudin, Bailly will publish some notes after his return to France and Peron includes in the official report of the expedition observations of the geologists and other naturalists. Two other young men, official unskilled worker, were invited by Baudin to illustrate the logbook - Charles-Alexandre Lesueur and Nicolas-Martin Petit, both will became later the most skilled artists for animals and plants of the time.

During the long voyage Peron and Lesueur became friends and especially interested in the jellyfishes of the Atlantic Ocean - the drawings made by Lesueur of the discovered specimens will much later even inspire the artwork of the German zoologist Ernst Haeckel.

Fig.2. Lesueur´s depiction of jellyfishes for the "Voyage de decouvertes aux Terres Australes", published in Paris 1808-1811 (figures from here), Image of introduction Macropus fuliginosus (Western grey kangaroo) also by Lesueur.

In March 1801 the ships reached the Ile de France, the modern island of Mauritius, and lost 10 naturalists - they decided to abandon the expedition and remain on the island. The expedition nevertheless continued and in April the two ships left behind Mauritius, on 27. May 1801 the bare land of Cape Leeuwin, Australia, was in sight.

Fig.3. The route of the expedition by Baudin, in the background Louis de Freycinet´s (1779-1842) "Carte générale de la Nouvelle Hollande", published in 1811 as part of the results of the 1800-1804 expedition (map from here and here, modified).

The first naturalists went on land in the Wonnerup Inlet, and begun avidly collect specimens of animals and samples of rocks.
A storm forced the men to remain on land, only after several days they finally were able to reach their ships, but during the attempt one man died. The storm separated the two ships, which proceeded with the expedition independently to the island of Timor, a Dutch colony, where the majority of the crew fell ill by Malaria and other tropical diseases.
Nevertheless still the expedition continued, and in November 1801 they reached Tasmania, where they remained for three months.
Peron and Lesueur studied, collected and draw the new and unknown fauna and flora, and also the indigenous people which they encountered in the second part of the voyage. Again the two ships lost each another.
The "Geographe" on 8. April 1802 encountered the British vessel "Investigator" under the command of Matthew Flinders. The expedition of the "Investigator" will map large part of the southern coast of Australia during the years 1801-1803, and prove that Australia is one large continent, not two islands separated by a strait, as some geographers (and Napoleon) assumed previously. This were bad news, the lack of a strait meant that the British Empire could claim an entire continent for it's own.

The "Geographe" continued their scientific exploration, until reaching on 20. June 1802 Port Jackson, the modern Sydney, soon followed by the "Naturaliste". The expedition had collected until then more than 40.000 specimens - so it was decided that the "Naturaliste" would turn back to France with a part of the collection; the "Geographe" would proceed to study the southern coast of Australia.
On Kangaroo Island Baudin caugth, appropriately, a dozen of living kangaroos and some emus, and stored them in the carbines of the crew. The animals soon became sea sick and the majority of them died before the end of the expedition; the surviving specimens were intended as a gift to the garden of the French queen Josephine.

With Baudins expedition the first academic naturalists and geologists explored Australia - a continent which geology was completely unknown to Europeans.
The expedition's geologist, Louis Depuch and Charles Bailly, followed a four-fold scheme of rock classification, developed in Europe, and taught by the famous French geologist Déodat de Dolomieu. They recognised primary rocks, such as granite; secondary rocks, such as stratified sandstone and limestone; alluvium; and local volcanic rocks, such as basalts. The French geologists' recording of these four categories of rocks in Australia confirmed their world-wide distribution, an important step to establish general valid categories in geology. Together with the zoologist François Péron, who also carried out geological investigations, the French geologists were the first to establish the presence of a chain of highlands along the eastern coast of the Australian continent.

Peron noted also on the western coast of Australia horizontal bedded sand- and limestone (today referred as Tamala-Limestone and considered an aeolian sediment of the Pleistocene), and concluded, based on similarities in the content of lime and sand, that these sediments were deposited on the beach, and later cemented by calcareous substances (an early insight on diagenesis of sedimentary rocks). However he misidentified larger calcareous concretions as single pebbles, and denominated layers with such nodules as "breccias".
Peron assumed from the position of the single layers above the ocean a change of the sea level during geological time - the sediment was explainable by deposition of sand and consequent retreat of the sea. An important observation at a time when worldwide sea level changes were necessary to sustain the Neptunism-geology, where all rocks form by crystallisation from water and so in the past must have been covered by the sea. Peron wrote:

"One of the greatest achievements of modern geology research and also one of its most indisputable, is the certain knowledge that, in the past, the level of the sea was higher than at the present time. At almost all places in the old and the new world is the proof of this phenomenon as numerous as it is evident. Only in les Terres australes was this still to be ascertained as, by virtue of its immense areal estent, it could have proved to be an important exception to the universality of the former domination of the ocean over the land."
(PERON & FREYCINET 1816)

Fig.4. Lesueur´s and Petit´s depiction of Van-Diemen´s-Land for the "Voyage de decouvertes aux Terres Australes". The granitic rocks found on the island of Tasmania convinced Peron and the other geologists that the most ancient - the primary - rock was Granite, forming the basement of the continents - in accordance to the geological view of Neptunism.

During the expedition the naturalists and the crew faced many danger, however in part injuries or dead were a result of negligence by members of the expedition.
In Shark Bay Peron and other naturalists went on land to collect seashells, ignoring the orders of Captain Baudin, and soon were lost in the desert. Only two days later they were accidentally found and saved. Baudin confined the rebellious zoologist on the ship.
Peron never forgot, as he saw it, this affront, and later, in the official report of the expedition did not name once the captain of the expedition, and if he mention him he inculpated him to be to careless. However during the entire expedition only 32 men died, 13% of the crew, a surprisingly low percentage considering the period.
Capitan Baudin tried to proceed until the gulf of Carpentaria, following his orders, but soon diseases spread on the ship and the fresh water supply became low, Baudin decided to turn back. Soon after Capitan Baudin died of fever on the island of Timor victim as many others of the dangers and deprivations on these expeditions.

In 1804 the "Geographe" sailed into the harbour of Le Havre, however there were no official welcome or celebration, as three years earlier - the ongoing war between French and England now was more important.
The expedition was the most successful until these times, 220.000 samples of animals, plants and rocks collected, and 73 living animals, 3 kangaroos, 2 emus and 3 wombats - the first of their kind to be seen in Europe - brought back.

Fig.5. The original hand coloured copper engraving of this Short -legged Emu (now extinct) on Kangaroo Island was engraved by F. Lambert after paintings and drawings by Charles-Alexandre Lesueur for the "Voyage de decouvertes aux Terres Australes".

However the achievements of Baudins expedition will be forgotten until the 20the century - why?
One cause was the dead of some of the most important naturalists during the expedition, one of the geologists and the chief-botanist, also Baudin was dead - there was simply nobody of high reputation left to care about the results of the voyage.
A second cause was the lack of support from the authorities. The expedition of the "Investigator " had reassured the predominance of the British Empire in Australia, Baudins expedition therefore was considered by politicians a failure, Napoleon and the government showed little interest in financing further work, like the publication of the results or payment for the surviving naturalist, weak and ill from three years of dangers and deprivations.
Peron can publish the official report and an atlas containg some plates of the travel only in 1807, after hard work and a long struggle for the money, entitled "Voyage de decouvertes aux Terres Australes", and dies just three years later in 1810, before the completion of the second volume, published posthumous by the geographer Freycinet.

There was still a possibility for the Baudin´s collection to earn some fame, but again something went wrong.
The collection of molluscs and sea shells brought back from the expedition influenced the work of an important French naturalist, Jean-Baptiste de Lamarck.
Peron had discovered on the coasts of Tasmania a bivalve with a peculiar triangular shape - Trigonia antarctica - and recognized the similarities of this living species with fossil species known until then only from the Tertiary sediments of the basin of Paris and assumed extinct.

Fig.6. Specimen of Trigonia sp. from lower Cretaceous sediments of Bavaria (Germany). Below: One of the many fossil species of Trigonia found commonly in some of the older Secondary formations, as illustrated by Bruguiere for the Encyclopedie Methodique (1797) (after RUDWICK 2005).

In 1804 Lamarck published the discovery; this example seemed to support his idea that species are not fixed entities but change over time.
Unfortunately Lamarck mixed detailed natural observations with wild speculations, he saw correctly that there are differences of organisms through time, however he could not explain why there should be a change beside to a final cause or mysterious force and his explanations were later regarded by Darwin as "useless".
If Lamarck had recognized that there is no distant final cause to reach for an organism - a good example were the many "primitive" mammals of Australia - but only the survival now, he maybe would have discovered the most important theory in biology 50 years earlier then Darwin.
C'est la vie...

Bibliography:

GLAUBRECHT, M. & MERMET, G. (2007): Josephines Emu oder Die Geschichte einer vergessenen Expedition. GEO Nr.6/2007: 98-122
MAYER, W. (2008): Early geological investigations of the Pleistocene Tamala Limestone, Western Australia. from GRAPES, R.H.; OLDROYD, D. & GRIGELIS, A. (eds) History of Geomorphology and Quaternary Geology. Geological Society, London, Special Publications 301: 279-293
MAYER, W. (2009): The Geological Work of the Baudin Expedition in Australia (1801-1803): The Mineralogists, the Discoveries and the Legacy. Earth Sciences History Vol.28 (2): 293-324
RUDWICK, M.J.S. (2005): Bursting the limits of time - The reconstruction of Geohistory in the Age of Revolution.The University of Chicago Press, Chicago, London: 708

Welcome to the Boneyard 2.4!

What are they?

Creations of mind?- The mind can make Substance,
and people planets of its own
With beings brighter than have been, and give
A breath to forms which can outlive all flesh
"The Dream", Lord Bryon (1788-1824)

Thanks to many participants (and a little call by David) this month Boneyard can present again a large variety of different time epochs and animals. We range from the Cambrian to a distant future still to come, we will hear tales from the early arthropods and from the archosaurs, with a guest appearance of three insolent monotremes, we will find the fossils in the field, look artists at work to reconstruct dinosaurs and visit a museum.

Observing the images of an ancient creature displayed in a book or found in the internet we tend to forget how many persons and how many work and knowledge is involved in the reconstruction of the past.
The first step to display an organism in a museum is to find evidence of its former presence in the field, comprising bones, shells and tracks. In some cases the presence of fossils is so abundant, that entire cabins were build by locals using fossil bones, as in Wyoming seen by ScienceBuzz.

But in most cases fossils tend to be hidden under the surface of earth, a tough place where rocks can become metamorphic and fossils destroyed. But sometimes sediments can escape such a fate, and the field researcher can find wonderful fossils and study the environment where they became deposited. One such example is the Barrandium in the land of the trilobites, where naturalists of the 19th century discovered the most ancient live forms known at these times.

Fig.2. "The trilobites", collector cards from the "Animals of the Prehistoric World" by Heinrich Harder 1916 (images from copyrightexpired.com).

There are still today such localities, even if sometimes it is hard to get to them. What for example is still hiding in one of the most remotes place of earth - Tarchia at Pseudoplocephalus introduces us to a cool theropod, why he is important for the phylogeny of carnivorous dinosaurs and how an expedition to the end of the world hopes to discover more about it.

Fig.3. "Teleosaurus", collector cards from the "Creatures of the Primitive World" by F. John 1902-1906.

Another vertebrate group of the archosaurs experienced important discoveries in the last years, but here the problem is not so the inaccessibility of some localities, but the lack of interest of newsletter to report their story - but it is not good that these stories are forgotten, so Susan remember us at The Forgotten Archosaurs the tale of the "crocodile of Bauru".

As the fossils are recovered, more detailed research is carried out to understand the structure of the former living organism. Sometimes what is found is very complex and to explain it is cryptic, the anatomy of flying archosaurs of the Mesozoic baffled the naturalist in the 18th and 19th century - but have you ever heard of the terrible fanged, blood-sucking, demon turtle from the Upper Cretaceous?
Actually David Tana at Superoceras presents the facts behind the myth of Chupacabrachelys complexus.

Fig.4. "Meiolania", collector cards from the "Creatures of the Primitive World" by F. John 1902-1906.

Modern palaeontology and development of new technologies have increased the information's that can be extracted from fossils. The signs left on the bones by muscles can give clues for the reconstruction of soft tissues, comparative anatomy shows how bones are arranged in a skeleton, but also careful observations of modern animals can inspire artists.

Fig.5. "Hydrosaurus", collector cards from the "Creatures of the Primitive World" by F. John 1902-1906.

One possibility to understand anatomy is to reversing the process, by comparing living reptiles and their bony counterpart the artist can grasp better the distribution of soft tissue, doing so david's really interesting pages shows what we can learn from the modern genus Varanus about dinosaurs.
In a similar way The Optimistic Painting Blog displays the process by which an awesome attacking Styracosaurus came back to life by various steps.

Fig.6. "Torosaurus", collector cards from the "Creatures of the Primitive World" by F. John 1902-1906.

This image brings us to the next question and another Boneyard submission - to what would you compare the gait of a large ceratopsian? Tentative approaches included lizards (to small) and elephants (still to small). Studying, analyzing, digitalising and modelling the bones of Chasmosaurus irvinensis, the team of the Canadian Museum of Nature and computer expert Alex Tirabasso decided to use a computer-aided approach and the results of his 3-Dino can be found here.

Fig.7. "Archeopteryx", collector cards from the "Animals of the Prehistoric World" by Heinrich Harder 1916.

Bones are evidences that enable us to reconstruct a reasonable model for the past. For many aspects of primordial life however evidence is still missing, this comprises especially the behaviour of extinct organisms. So Albertonykus from Raptormaniacs is arguing in a three chapter comic above puggles, why males are not always as smart as they think they are and how short some theropds possibly remained in their nest.

Fig.8. Painting of Arthur Lakes (1844-1917) showing the hard work to recover dinosaur bones from the Como Bluff site, entitled "Professor Mudge" and his new finds (period of 1877-1889).

Finally, when the (preliminary) science is done, the artwork terminated, it is time to display the findings in a museum and present them to the public. Love in the Time of Chasmosaurs introduces us to the children's museum of Indianapolis and especially the work that is done "behind" the exposition, often forgotten but essential to run a museum.

Fig.9. "Iguanodon", collector cards from the "Creatures of the Primitive World" by F. John 1902-1906. Today we know that many of these representations are incorrect, but at the time of drawing it was a reasonable approach - these artists and naturalists were the pioneers of such art. Thanks to new discoveries and fossils our knowledge has improved, and so the possibility of the artists to display former life forms.

The displayed fossils in their showcase are one of the most compelling proofs of past evolution, a process still ongoing. For the specimen in the showcases the tale is not yet over - they can inspire people, like scientists as artists - Tricia´s Obligatory Art Blog! introduce us to possible fossils of a distant future, as imagined by Dougal Dixon and based on how evolution "worked" until now - and by the way dinosaur-fossils can also provide a rock opera -yeah!

Let´s conclude with the words of an palaeo-blogger of old date:

"Beyond the awesome grandeur of the reconstructed skeletons of Gorgosaurus, Triceratops, and other long-lost creatures, every single bone has a story to tell about the life and evolution of the animal it once belonged to. The skeletons of the dinosaurs are much more than static monuments of a bygone age; they are intricately detailed records of an ongoing evolutionary "experiment" that has been carried out on this planet for the past 3.5 billion of years and provide the context for understanding our own evolutionary history."
Brian Switek, Time and Change, from Written in Stone (2010).

So we came to the end of this December edition of the Boneyard, many thanks again to all the palaeo-blogger who contributed and send in their posts and thoughts about the past, and remember for the future the next edition of the monthly Boneyard will be hosted on January 4, on When Pigs Fly Returns and to remain up to date with the newest development on the Boneyard visit the official blog.

In the land of the trilobites

"Consequently, if my theory be true, it is indisputable that before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown, periods of time, the world swarmed with living creatures."

Charles Darwin in "On the Origin of Species" (1859), the Silurian of Darwin's time corresponds to the modern Cambrian.

Fig.1. The restaurant "Trilobit" in the old city of Prague. The Czech Republic is very proud of its fossils and role in the history of geology, the city of Skryje for example has in it Civic Heraldry even a trilobite, inspired by the species Skreiaspis spinosus (thanks to Dr. Astudillo-Pombo for the information).

Barrandium is the denomination of the stratigraphic succession of a northwest-southeast stretching synclinale, also referred as Basin of Prague, in the Czech Republic. The sediments preserved here were deposited after the Caledonian orogeny (490-390Ma), and survived the Variscian orogeny (ca. 350-320Ma) without being metamorphosed - thus they are a unique window in a distant geological past and provided insights of life and habitats during the Palaeozoic, from the Cambrian (542Ma) until the Devonian (359Ma), but especially from the Silurian period (443-416Ma).

Fig.2. Trilobites-fragments from the Cambrian assemblage of Skryje-Tyrovice area, mostly Paradoxides and Hydrocephalus, below non identified, well preserved specimen.

It was the French Joachim Barrande (1799-1883) to describe and study for the first time these sediments, and the name of the succession and many animal species bear his name to remember this extraordinary man.

Fig.3./4. Barrande´s monument in the garden of the school of Skryje was made by the Czech sculptor M.V. Dobrovolny in 1969.
Joachim Barrande discovered the rich palaeontological localities at Skryje and Tyrovice in 1833 when he carried out there explorations for a planned horse-railway. Fossils of the Cambrian age, designated by Barrande as the "Primordial fauna" were at the time the oldest known fossil remains.
Below, plate 5 from the supplement to Barrande´s work "System Silurien du Centre de la Boehme" (1872).

Barrande was an engineer and geologist, but between 1833 and 1846 he gradually changed to palaeontologists and stratigrapher, publishing his important "Preliminary Notes" about trilobites and sediments of Bohemia (the western part of modern Czech) in 1846; 1846-1852 he successfully tried out his new "profession", and already in contact with many scientists in Europe, published in 1852 the first two volumes of his later famous "System Silurien du Centre de la Boehme"; finally from 1852 to his death he published 19 more volumes of about 6950 pages and 1148 tables.

Generations of researchers have followed his tracks, and tried to reconstruct the biostratigraphy and the development of the Basin of Prague. The ghost of Barrande, the history of research and the value of these sediments for the development of geology and palaeontology are well recognized in the beautiful city of Prague. Many unusual signs in the street celebrate the animals of the past, most iconic of them the extinct arthropods known as trilobites.


The Silurian is one of the most enigmatic epochs in the history of earth; marked by a glaciation at the beginning, it was at the end of this period that the landmasses, until them barren deserts, became settled by plants and animals. But the shelf-regions of the continents were a rich habitat, populated by trilobites, brachiopods, crinoids and other invertebrates.

In the Silurian the Basin of Prague was located at the northern shores of Peri-Gondwana-Land (the Southern Continent of these times), then during the Silurian Peri-Gondwana begun to move from the poles to the equator. These profound changes influenced also the deposited sediments; there is a progressive change from predominately clastic sedimentation (sandstones, volcanic deposits) to black shales of an anoxic ocean to limestone and "reef"-deposits of a warm, shallow sea. This is not only a result of the change of paleolatitude of Peri-Gondwana, but also a sign of earth's climate warming after a pronounced cooling during the Ordovician and Silurian.

Fig.6. Simplified Geology and Stratigraphy of the Barrandium.

The unmetamorphic stratigraphy of the Barrandium, the many distinctive horizons of volcanic ash and the rich fossil fauna made it a preferred place to define here various GSSP (Global Boundary Stratotype Section and Point), outcrops used as reference sites where the single limits of the chronostratigraphic periods, used to subdivide geological time, are defined.
The Pridoli-epoch (418,7-416,0Ma) is the last epoch of the Silurian and it is named after the Pridoli-Formation (or Pozary-Formation), and the official GSSP is situated since 1985 in the Pozary-quarry, located at the periphery of Prague. Here in various quarries of the 19th century the complete sediment- succession of the upper Silurian until the lower Devonian is accessible, first clays with tuff-layers (Kopanina-Formation), followed by layers of biodetrital limestone, rich in fragments of cephalopods, brachiopods and trilobites, and finally a succession of thin bedded marls and limestone (Pridoli-fm). This succession is also visible in the nearby quarry of Muslovka.

Fig.7. The quarry of Muslovka, where the transition from the Kopanina-fm (Ludlow, 422-418Ma) to the Pozary-fm (Prídolí, 418-416Ma) is well visible- Legend: a) mudstones and limestone with ash-layers of the Encrinuraspis beaumonti zone, b) limestone of the Metacalymene baylei zone; c) limestone of the Ananapsis fecunda zone ; d) bedded limestone of the Prinopeltis archai zone.

Fig.8. Fragments of crinoid-stems and brachiopod Septatrypa sp. of the Pozary-fm found in the Muslovka quarry.

To observe the lower Silurian stratigraphic succession and find more fossils the quarry of Kosov, located near the city of Beroun, is a perfect place. Here black shales of the Motol-fm with abundant planktonic graptolites can be found.

Fig.9. Black shales of the Motol-fm with Neocullograptus kozlowskii (?).

The dominance of the graptolites, the lack of benthic organism and the lamination of the rocks was caused by a reduction of water currents and circulation of the Silurian sea, resulting in a hostile, anoxic environment where the mud accumulated undisturbed by digging organisms. One possible explanation for the reduced circulation observed in many similar deposits could be the global cooling at these times.
In the upper part of the Motol-fm single limestone layers appear, until a gradual transition to a succession of bioclastic limestone and clays of the Kopanina-fm occurs. The limestone layers and the abundance of fossils are evidence of a restored circulation and oxygenation of the water. Single volcanic events, recognizable by the ash and clay-layers, killed from time to time the organism living in this sea, buried and conserved them until today.

The graptolites, and especially the vast group of the trilobites dominated the Palaeozoic, but finally all of them disappeared. The graptolites in the Carboniferous, the trilobites in the mass extinction at the end of the Permian about 250 million years ago - only the fossils remain to tell their extraordinary story.

Fig.10./11. Kopanina Formation as seen in the Kosov quarry, with typical alternation of dm-thick layers of limestone with clay-layers and tuffites - the small image shows also the typical lens of limestone interbedded in the layers. Below image of thorax/pygidium of Acantholomina minuta found in an ash-layer.

Bibliography:

BARRANDE, J. (1872): Systeme Silurien du centre de la Boehme. 1st Partie: recherches Paleontologique. Supplement au Vol. I - Trilobites, Crustaces divers et Poissons. Prague - Paris.
CHLUPAC, I. (1993): Geology of the Barrandian - A field trip guide. Senckenberg- Buch 69. Verlag Waldemar Kramer, Frankfurt am Main.
KRÍZ, J., (1989): The Prídoli Series in the Prague Basin (Barrandium area, Bohemia). In: Holland, C. H. and Bassett, M. G. (eds.). A global standard for the Silurian System. National Museum of Wales, Geological Series 9, Cardiff: 90-100
LEHNERT, O.; FRYDA, J.; BUGGISCH, W.; MUNNECKE, A.; NÜTZEL, A.; KRIZ, J. & MANDA, S. (2007): 13C records across the late Silurian Lau event: New data from middle palaeo-latitudes of northern peri-Gondwana (Prague Basin, Czech Republic). Palaeogeography, Palaeoclimatology, Palaeoecology. Vol. 245 (1-2): 227-244
RICKARDS, R.B. & WRIGHT, A.J. (1999): Systematics, Biostratigraphy and Evolution of the Late Ludlow and Prídolí (Late Silurian) Graptolites of the Yass District, New South Wales, Australia. Records of the Australian Museum Vol. 51: 187-214

Goliath-kangaroo extinction

Kangaroos are one of the most emblematic animals of the fauna of the Australian continent; however the modern species are only remnants' of a much larger group. 50.000 years ago humans arrived on the continent; 45.000 years ago nearly 90% of the larger species of kangaroos went extinct, along with other large marsupials, reptiles and birds.
The extinction of the Pleistocene Megafauna has inspired many hypotheses, and at least for Australia and the pacific islands the contribution of humans seemed highly probable. Humans could effect large mammals, with low population densities and slow reproduction, direct by hunting them, or indirect by modifying or destroying their habitat - a combination of hunting and use of bush fires to clear the landscape by humans seemed the most convincing cause for the extinction event in Australia.

To verify this hypothesis two approaches are necessary, establishing an exact chronology of the extinction, the arrival and dispersal of humans on the continent, and understand the interrelationships between animals and humans - did humans hunt actively and effectively the disappeared species, and did they target and destroy specific habitats?

Fig.1. Thylacoleo sp. hunting the Goliath-kangaroo Procoptodon goliah in Australia some 50.000 years ago, raffiguration by the Spanish paleo artist Mauricio Anton (2004).

A study of the anatomy of the biggest kangaroo species known, Procoptodon goliah, revealed that in contrast to old theories is was rather a browser then a grazer, feeding probably on plants of the Chenopodiaceae - family, and surviving in the arid environment of the steppe.
This observation seems to rule out the effect of climatic changes during the last glacial maximum, resulting in a dry continent, to the demise of the species - Procoptodon adapted and evolved to handle the new climate.
The scrubland steppe, with inhomogeneous distributed "fuel", is also a landscape where fires and landscape burning would be less effective, it seems reasonable to argue that it was not the primary target for human hunters or colonizers.

These two observations seem to support the last factor, active hunt, as one of the major causes contributing to the extinction of the Pleistocene fauna.
However such an affirmation is problematic, it is very hard to confirm such a claim based not on direct evidence, but by elimination of other possibilities - ruling out factor A or B doesn´t automatically verify factor C.

Archaeological site with occurrence of both species of the megafauna and humans are rare, and in part highly controversial. Most archaeological sites of the first occupation of Sahul and the period of faunal change are lost today, covered by the rising sea after the last glacial maximum. This makes is very difficult to quantify if, and how long humans and extinct species lived together. Archaeological evidence for active hunting of large species is also missing.

The controversy is far to be over, but the preliminary study of the ecology of Procoptodon shows how detail research on the single species, rather then a general fauna, can give more concrete clues to establish the causes of an ecosystem demise.

Bibliography:

PRIDEAUX, G.J.; AYLIFFE, L.K.; DeSANTIS, L.R.G.; SCHUBERT, B.W.; MURRAY, P.F.; GAGAN, M.K. & CERLING, T.E. (2010): Extinction implications of a chenopod browse diet for a giant Pleistocene kangaroo. Proceedings of the National Academy of Sciences Vol.106 (28): 11646-11650

Accretionary Wedge 29 - Geologic features of 'home' I do not like

Ann on "Ann's Musings on Geology & Other Things" is hosting the 29# edition of the Accretionary Wedge, dedicated to the geological features one likes, but also doesn't like of his neighbourhood.

Making a living as field geologists in the Eastern Alps has some advantages, there is a great variety of rocks to map and you can easily pass from the valley floors with cities and villages, passing by dark forests to the bleak peaks of the mountains.
But this dualisms of the landscape also hides a great injustice to the geologist. Humans tend to build and live in the lower storeys of the mountains, areas mostly covered by boring rubble and nasty plants, zones where the outcrop-quality and quantity is scarce and low.
The higher storeys of the mountains have excellent outcrops, but you rarely will find somebody who pays you to map these zones. So you have to suffer and map zones in the middle of the forest, and in the rare glades you can spot the distant mountains, like sirens calling, and like a fata morgana unapproachable.

The cruel truth

Sometimes it is hard to be in the field, maybe better turn back...

...oh, well, never mind...

Finally out of the forest...

Outcrop No.1.

Where is the next outcrop... I think I will map "Quaternary undifferentiated", what's planned for tomorrow ? ... map area "thorny shrubbery"…