Thursday, 31 January 2019

APODEROCERAS, YOUR GRACE

This stunning specimen with her regal ridges (and small anomaly) is an Apoderoceras ammonite. Apoderoceras are an extinct genus of cephalopod, an active predatory mollusk belonging to the subclass Ammonoidea.

Apoderoceras is, in fact, a wonderful example of sexual dimorphism within ammonites as the macroconch (putative female) shell grew to diameters in excess of 40 cm – many times larger than the diameters of the microconch (putative male) shell. Apoderoceras has been found in the Lower Jurassic of Argentina, Hungary, Italy, Portugal, and most of North-West and central Europe, including as this one is, the United Kingdom. She was found on the beaches of Charmouth in West Dorset, then prepped expertly by the lovely and talented Lizzie Hingley. 

Neither Apoderoceras nor Bifericeras donovani are strictly index fossils for the Taylori sibzone, the index being Phricodoceras taylori. Note that Bifericeras is typical of the earlier Oxynotum Zone, and ‘Bifericeras’ donovani is doubtfully attributable to the genus.

The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of genus Apoderocerasas and of Bifericeras donovani the defining biological marker for the start of the Pliensbachian Stage of the Jurassic, 190.8 ± 1.0 million years ago.  As the brilliant Murray Edmunds points out, this lovely large specimen (macroconch) of Apoderoceras is likely a female. Her larger body perfected for egg production.

Apoderoceras (Family Coeloceratidae) appears ‘out of nowhere’ in the basal Pliensbachian and dominates the ammonite faunas of NW Europe. It is superficially similar to the earlier Eteoderoceras (Family Eoderoceratidae, of the Raricostatum Zone), but on close inspection can be seen to be quite different.  It is therefore an ‘invader’ and its ancestry is cryptic.

The Pacific ammonite Andicoeloceras, known from Chile, appears quite closely related and may be ancestral, but the time correlation of Pacific and NW European ammonite faunas is challenging. Even if Andicoeloceras is ancestral to Apoderoceras, no other preceding ammonites attributable to Coeloceratidae are known. (Maybe there are clues in the Lias of Canada?) Apoderoceras remains present in NW Europe throughout the Taylori Subzone, showing endemic evolution.

It becomes progressively more inflated during this interval of time, the adult ribs more distant, and there is evidence that the diameter of the macroconch evolved to become larger. At the end of the Taylori Subzone, Apoderoceras disappeared as suddenly as it appeared in the region, and ammonite faunas of the remaining Jamesoni Zone are dominated by the Platypleuroceras–Uptonia lineage, generally assigned (but erroneously, IMO!) to the Family Polymorphitidae.

In the NW European Taylori Subzone, Apoderoceras is accompanied (as well as by the Eoderoceratid, B. donovani, which is only documented from the Yorkshire coast, although I know of examples from Northern Ireland) by the oxycones Radstockiceras (quite common) and Oxynoticeras (very rare), the late Schlotheimid, Phricoderoceras (uncommon: note P. taylori is a microconch, and P. lamellosum the macroconch), and the Eoderoceratid, Tetraspidoceras (very rare).

Thank you to Murray Edmunds for his advice, guidance and corrections as we explore Apoderoceras and the ammonite faunas of the Pacific and NW Europe. You are deeply awesome, my friend!
Check out Murray’s Research Gate site for more interesting tidbits!

https://www.researchgate.net/profile/Murray_Edmunds

Wednesday, 30 January 2019

DINOGORGON: TERROR OF THE LATE PERMIAN

Dinogorgon Rubidgei / Photo: Jonathan Blair / Corbis
A quarter of a billion years ago, long before dinosaurs or mammals evolved, this three-metre (10-foot) gorgonopsid, Dinogorgon, terrorized the floodplains of what is now South Africa and Tanzania during the Late Permian.

For many years, we've believed that these mighty hunters reigned and died out in less than a million years. Dinogorgon is meant to have vanished during one of the greatest mass extinction events on the planet, the Permian Extinction. We've recorded five mass extinction events in our humble 4.6 billion year history. The event from the Permian wiped our about nine of every ten plant and animal species on the planet. New fossil evidence suggests that there were actually two mass extinctions during this time, with a sixth event happening around 260 million years ago.


Tuesday, 29 January 2019

UPPER CRETACEOUS NANAIMO GROUP

Upper Cretaceous Nanaimo Group / Denman Island
The Upper Cretaceous Nanaimo Group of southwest British Columbia is a four-kilometre thick succession of mostly deep marine siliciclastics sitting directly above the Insular Superterrane.

This succession has been the focus of many paleomagnetic, isotope geochemistry, paleontology, and sedimentology studies with the aim of untangling the tectonic history and paleolatitude of the Insular Superterrane during the Nanaimo Group deposition some 90 to 65 million years ago.

One would think that these research papers would support each other in terms of that deposition. Much to our chagrin, we're still working through the strata to define both the formal stratigraphy, untangle if it was deposited in single or multiple basins and match it up with local and regional correlations.

The upper two-thirds of the succession is continuously and well exposed on Denman and Hornby islands and represents the best example of this part of the succession in the northern half of what we consider the single Nanaimo Basin. This area includes the previously only informally defined type areas for the Geoffrey and Spray formations, defined here formally for the first time with type sections and detailed descriptions. New interpretations of the geology of these islands demonstrate that previously interpreted major faults do not exist, resulting in stratigraphic and age controls that are both different and simpler than previously interpreted. The redefined stratigraphy of the northern part of the basin is remarkably similar to that of southern areas in both type and age, affirming both a single basin evolution and a single stratigraphic nomenclature.


Saturday, 19 January 2019

SLOTHS AND AVOCADOS

In 1788, this magnificent specimen of a Megatherium sloth was sent to the Royal Cabinet of Natural History from the Viceroyalty of Rio de la Plata.

The megaterios were large terrestrial sloths belonging to the group, Xenarthra. These herbivores inhabited large areas of land on the American continent. Their powerful skeleton enabled them to stand on their hind legs to reach leaves high in the trees, a huge advantage given the calories needed to be consumed each day to maintain their large size.

Avocados were one of the food preferences of our dear Giant ground sloths. They ate then pooped them out, spreading the pits far and wide. The next time you enjoy avocado toast, thank this large beastie. One of his ancestors may have had a hand (or butt) in your meal.

In 1788, Bru assembled the skeleton as you see it here. It is exhibited at the Museo Nacional De Ciencias Naturales in Madrid, Spain, in its original configuration for historic value. If you look closely, you'll see it is not anatomically correct. But all good paleontology is teamwork. Based upon the drawings of Juan Bautista Bru, George Cuvier used this specimen to describe the species for the very first time.

Friday, 18 January 2019

Wednesday, 16 January 2019

THE LAST ICE AGE

The massive ice sheets of the Pleistocene covered much of the planet. They contained so much of the Earth's water that sea levels dropped to 100 metres lower than they are today.

Tuesday, 15 January 2019

FIRST ITALIAN FOSSILS OF AGRIOTHERIUM

Agriotherium / Short-Faced Bear
Fossil remains of Agriotherium, the short-faced giant bear, have been found in Collepardo, Italy. A fragment of a mandible was unearthed back in 2015 in the province of Frosinone. Thanks to several years of research and a recent CT scan, the team from Sapienza University of Rome were finally ready to publish.

Agriotherium is one of the largest of the mighty carnivores that lived in Europe back in the Pleistocene. They weighed as much as 900 kilos (almost 2,000 lbs) and grew up to 2.5 meters tall. These ancient bears roamed prehistoric Italy amid a humid and temperate climate, competing for food resources with some of our ancestors as they only becoming extinct 2.6 million years ago.

Monday, 14 January 2019

CAMBRIAN SEA ANEMONE

A stunning Cambrian soft-bodied Sea Anemone from outcrops near Malong, China. Collection of Marc R. Hänsel

Sunday, 13 January 2019

PREHISTORIC BUGS: WANNERIA DUNNAE

Wanneria dunnae, an impressive trilobite from British Columbia's Eager Formation near Cranbrook. Trilobites were among the earliest fossils with hard skeletons. They were the dominant form of life at the beginning of the Cambrian Period. This specimen of Wanneria dunnae from the East Kootenay of British Columbia is typical of the group. Trilobite eyes were compound like those of modern crustaceans and insects. The eyes of these earliest trilobites are not well-known as the visual surface dropped away and was lost during molting long before they ever became fossils.

Saturday, 12 January 2019

Thursday, 10 January 2019

FIRE-KISSED ARTHROPOD

This fellow is Chengjiangocaris kunmingensis, a rather glorious fuxinhuiid arthropod. While he looks like he could be from the inside of the Lascaux Caves and their fire-kissed Palaeolithic paintings, albeit by a very ancient Picasso, he was found at a Cambian fossil site in southern China.

As his name indicates, he is from a fossil site in the Yunnan region near Kunming. He is unusual in many ways, both because of the remarkable level of preservation and the position in which he was found. This fellow was a bit of a tippy arthropod. His carapace had flipped over before fossilisation, allowing researchers to to examine this fuxianhuiid's head and legs in great detail without a carapace in the way.

The roughly 518-million-year-old site contains a dizzying abundance of beautifully preserved weird and wonderful life-forms, from jellyfish and comb jellies to arthropods and algae and is about 10 million years older than the Burgess Shale. Photo credit: Yie Jang (Yunnan University)

Wednesday, 9 January 2019

Tuesday, 8 January 2019

WASH ON, WASH OFF

If you were a fish living in the warm turquoise waters off the coast of Bonaire, you may not hear those words, but you'd see the shrimp sign language equivalent. It seems Periclimenes yucatanicus or Spotted Cleaner Shrimp is doing a booming business in the local reefs by setting up a fish washing service.

That's right, a Fish Wash. You'd be hard pressed to find a terrestrial Molly Maid with two opposable thumbs as studious and hardworking as this wee marine beauty.

This quiet marine mogul is turning out to be one of the ocean's top entrepreneurs. Keeping its host and diet clean and green, the spotted shrimp hooks up with the locals, in this case, local sea anemones and sets up a fish wash. Picture a car wash but without the noise and teenage boys. The signage posted is the shrimps' natural coloring which attracts fish from around the reefs.

Wash on, wash off.

Once within reach, the shrimp cleans the surface of the fish, giving the fish a buff and the shrimp its daily feed.

Monday, 7 January 2019

FRATERCULA ARCTICA

This lovely fellow is a Puffin or "Sea Parrot" from Skomer Island near Pembrokshire in Wales. They live about 20 years making a living in our cold seas dining on herring, hake and sand eels.

They are good little swimmers as you might expect but surprisingly they are great flyers, too! Once they get some speed on board, they can fly up to 88 km an hour. The sexy orange beak (dead sexy, right?) shifts from a dull grey to bright orange when it is time to attract a mate. While not strictly monogamous, most Puffin choose the same mate year upon year producing adorable chicks or pufflings (awe) from their mating efforts.

Sunday, 6 January 2019

ICHTHYOSAURIA

Ichthyosaurus was an extinct marine reptile first described from fossil fragments found in 1699 in Wales. Shortly thereafter, fossil vertebrae were published in 1708 from the Lower Jurassic.

Saturday, 5 January 2019

HOLCOPHYLLOCERAS MEDITERRANEUM

This lovely ammonite is Holcophylloceras mediterraneum (Neumayr 1871) from Late Jurassic (Oxfordian) deposits near Sokoja, Madagasgar.

Amazing suturing on this lovely ammonite and great detail, allowing us to see how he grew, adding to his size, chamber by chamber, building out his spiral shape.

Ammonite shells had many chambers divided by walls called septa. Nautiloids had simple septa with a single arc whereas ammonites developed septa with intricate folds, lobes and saddles. They also developed delicate feather-like or fern-like lacey patterns, called sutures, on the outer shell. You sometimes see them on polished or water worn specimens and in the photos of this fellow below.

The chambers were connected by a tube called a siphuncle which allowed for the control of buoyancy with the hollow inner chambers of the shell acting as air tanks to help them float. A bit like internal water wings you might use to learn how to swim as a kid.

We can see the edges of this specimen's shell where it would have continued out to the last chamber, the body-chamber, where the ammonite lived. Picture a squid or octopus, now add a shell. That's him!

Wednesday, 2 January 2019

ALSACE AMMONITE

A lovely example of the nautilus, Cératite Nodosus, from Shell Lime Superior deposits near Alsace in northeastern France on the Rhine River plain. Ammonite and nautilus shells are made up predominantly of calcium carbonate in the form of aragonite and proteinaceous organic matrix or conchiolin arranged in layers: a thin outer prismatic layer, a nacreous layer and an inner lining of prismatic habitat. While their outer shells are generally aragonite, aptychus are distinct as they are composed of calcite.


The aptychus we see here, hard anatomical structures or curved shelly plates now understood to be part of the body of an ammonite or nautilus, are often referred to as beaks. If you look closely at this specimen, you can see the beak of the nautilus, that wee pointed piece, near the centre. Collection of Ange Mirabet, Strasbourg, France.


Tuesday, 1 January 2019