All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
6 07, 2014

A Handy Ammonite Replica

By | July 6th, 2014|Key Stage 1/2, Key Stage 3/4|Comments Off on A Handy Ammonite Replica

Wild Safari Dinos Ammonite Replica

When it comes to teaching children about what fossils can and perhaps more importantly can’t tell us, a model of an Ammonite comes in very useful.  Ammonites are extinct members of the Mollusc family and closely related to extant (living today), cuttlefish.  These invertebrates lived in chambered, coiled shells and it is these shells and their moulds that are frequently found as fossils.  However, it can be difficult for the teacher to get the children to relate a fossil of a shell to the living, breathing animal.

Wild Safari Dinos Ammonite Model

A helpful, robust teaching aid.

A helpful, robust teaching aid.

Picture Credit: Everything Dinosaur

What did Ammonites Actually Look Like?

This difficulty can be overcome by showing the students a model of an Ammonite.  Although the shells of these cephalopods are common fossils particularly in Jurassic aged strata, very few preserved soft parts of prehistoric cephalopods have been preserved.  Palaeontologists believe that all Ammonites lived in the outer whorl of their shells, this is referred to as the body chamber.  As the Ammonite got bigger it extended its tubular shell and moved its body outwards, laying down new chamber walls behind it.  The earlier-formed chambers contained a mixture of water and gas which helped these marine creatures adjust their buoyancy.  The term cephalopod means “head foot”, a simple description of the body plan.  A series of ten arms surrounded the mouth, two of these appendages were specialised and capable of  grabbing and seizing prey.  The other arms would have helped manipulate food items and pull them closer to the mouth.  As these creatures are closely related to extant cephalopods they probably had complex eyes.  The Ammonite moved through the water by shooting jets of water out of a siphon (called the hypernome) which was positioned under the body.

Fossil Ammonites (Somerset, western England)

A cut and polished section of a Somerset Ammonite revealing internal chamber structure.

A cut and polished section of a Somerset Ammonite revealing internal chamber structure.

Picture Credit: Everything Dinosaur

The picture shows a cross section of an internal mould of an Ammonite, the internal structure and the sutures (edges of the chamber wall) can be clearly seen.

There are very few Ammonite replicas available, however, the fossil experts at Everything Dinosaur have a number of excellent, anatomically accurate replicas available.

To view a range of prehistoric animal models including an Ammonite replica: Prehistoric Animal Replicas

The model can be used to help explain how Ammonites lived and how the shells are preserved as fossils but only very rarely are the soft parts preserved.

Extension Ideas

Key Stage 2

  • Get the children to examine small Ammonite fossils and compare them to the replica, what clues about the life style of the Ammonite can be deduced?
  • What do you think Ammonites ate?  Where would they fit into a food chain?
  • Why did Ammonites die out yet close relatives like Cuttlefish and the Nautilus survive?  Can you encourage some independent research?

Key Stage 3

  • Compare the Ammonite model to pictures of extant cephalopods, what are the similarities, what are the differences?
  • What theories can be proposed as to why the Ammonites became extinct?
  • Have the students find many different types of Ammonite fossil pictures, look at the shells, why did so many different shell types evolve?  What does this say about the lifestyle, environment of individual species?

6 07, 2014

What Kind of Prehistoric Animal was Urvogel?

By | July 6th, 2014|Dinosaur Fans, Geology, Teaching|0 Comments

Explaining about Archaeopteryx

Earlier this week, Everything Dinosaur was emailed by a young dinosaur fan who asked about a prehistoric animal named Urvogel.  She had come across it whilst learning about the famous fossil site of Solnhofen in southern Germany.  The word “Urvogel” is German and it means “first bird”, it refers to Archaeopteryx (A. lithographica), the fossils of which are synonymous with the finely grained limestone beds of the Solnhofen quarries.

The Ancient “Dino-Bird” Archaeopteryx

the first bird - "Urvogel".

the first bird – “Urvogel”.

Picture Credit: Carl Buell

Palaeontologists now know that this creature, fossils of which show a transitional form between Theropod dinosaurs and birds, was probably not the first bird to evolve.  However, when a spectacular fossil discovery was announced in 1861, Archaeopteryx became the first feathered fossil of its kind to be formerly studied and its fossils caused a sensation, as only two years before Charles Darwin had published “The Origin of Species” that outlined the case for evolution and natural selection.

The Solnhofen limestone deposits are finely grained and they outcrop in an east to west belt north of Munich and south of Nuremberg.  Hundreds of fossils of invertebrates have been found and the vertebrate fauna preserved includes over fifty types of fossil fish, around thirty reptiles (Pterosaurs, marine reptiles, dinosaurs and crocodiles).  The Solnhofen deposits are regarded as a Lagerstätte.  This is a German phrase from the words Lager (which means storage) and Stätte (which means place).  It refers to a deposit of sedimentary strata that contains a lot of fossil material that is exceptionally well preserved.

During the Late Jurassic, shallow tropical lagoons and small islands stretched all the way from Portugal in the south through France and into southern Germany.  Coral reefs formed in the tropical seas and these reefs split the coastline up forming a series of isolated lagoons.  These lagoons were cut off from the sea and also from terrestrial run off.  The salinity levels rose in the lagoons and the water may have become oxygen deficient.  This made the mud on the bottom of these lagoons almost devoid of life so any animal or plant remains that drifted into the lagoon was not consumed by scavengers.  The almost stagnant waters had little current so the remains of corpses were not broken up.  Organisms buried by the soft, carbonate muds and formed as fossils in the finely grained sediment therefore have exceptional details preserved and many of these body fossils are almost complete.

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