All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
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22 06, 2020

Getting To Grips with the Jaws of Clevosaurus

By | June 22nd, 2020|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos|0 Comments

Did the Ancient Rhynchocephalians Out Compete Early Mammaliaforms?

Had you been around south Wales or south-western England some 200 million years ago, you would most probably have required a boat to get about.  The area around the Bristol channel today (where you still need a boat), during the Early Jurassic, consisted of a series of small islands surrounded by a warm, shallow tropical sea.  This archipelago (referred to as the Mendip Archipelago), was home to small dinosaurs and also to a variety of other reptiles including five species of Clevosaurus.  Clevosaurs are members of an ancient Order of reptiles called the Rhynchocephalia.  A new study published in the journal of the Palaeontological Association, suggests that these hardy reptiles may have filled the roles performed by early mammaliaforms on some of these small islands.

In addition, where Clevosaurus fossils are found, mammaliaform fossils tend to be lacking, so did these two types of tetrapod compete with each other for the same food resources?  This new research carried out by members of the School of Earth Sciences (University of Bristol), indicates that this could have been the case.  The scientists examined the biomechanics of the skulls of these lizard-like reptiles in a bid to gain an understanding of the likely diets of the species studied.  Different species of Clevosaur had different bite forces, which hints at a degree of niche partitioning within this genus.  This may explain why five different species were able to exist within a relatively small area.

Different Species of Clevosaurus may have had Slightly Different Diets

Niche partitioning within the Cleovosaurus genus.

Clevosaurus feeding habits – niche partitioning in Early Jurassic Clevosaurs.  The illustration shows two species of Clevosaurus associated with the Mendip Archipelago feeding on different types of insect prey.  Clevosaurus hudsoni feeding on a hard-shelled beetle, whilst (bottom), Clevosaurus cambrica consumes a softer insect without a carapace.

Picture Credit: Sofia Chambi-Trowell (University of Bristol)

Computerised Tomography Used to Analyse Skull Biomechanics

PhD student, Sofia Chambi-Trowell, from Bristol’s School of Earth Sciences, worked on CT scanned skulls of ancient rhynchocephalians and found differences in their jaws and teeth.

The student commented:

“I looked at skulls of two closely related species of Clevosaurus, Clevosaurus hudsoni and the slightly smaller Clevosaurus cambrica – the first one came from a limestone quarry near Bristol and the other one from South Wales.  Clevosaurus was a lizard-like reptile, but its teeth occluded precisely, meaning they fit together perfectly when it was feeding.  But what was it eating?”

Rhynochocephalians (beak heads), were a very successful, globally distributed group of diapsid reptiles that flourished during the Mesozoic.  The Tuatara (Sphenodon punctatus), is the only living member of this order, the Tuatara is confined to small islands off the coast of New Zealand and some specially designated and protected release sites on North Island.

Whilst studying the extant Tuatara is of great assistance to palaeontologists, expanding any findings to extinct members of this group is challenging.  Likewise, identifying the feeding habits of long extinct species is equally difficult.  However, finite element analysis conducted on two, near complete, three-dimensionally preserved skulls (Clevosaurus hudsoni and Clevosaurus cambrica respectively), provided bite force data and an assessment of jaw biometrics.  From this information, the potential feeding preferences of these two closely related reptiles could be inferred.

The Last of the Rhynochocephalians – A Tuatara

Tuatara.

A Tuatara.  It may resemble a lizard but the Tuatara is the last living example of the Order Rhynchocephalia.

Picture Credit: Everything Dinosaur

The researchers found that Clevosaurus had bite forces and pressures sufficient to break down beetles, and even small vertebrates easily, suggesting they could have taken the same prey items as the early mammals on the islands.  Calculations of muscle forces show that Clevosaurus hudsoni could take larger and tougher prey than the more slender jaws of Clevosaurus cambrica.

Co-author of the scientific paper and the project supervisor, Professor Emily Rayfield (University of Bristol) stated:

“We wanted to know how Clevosaurus interacted with the world’s first mammals, which lived on the Bristol islands at the same time.  I had studied their jaw mechanics a few years ago and found they had similar diets and that some fed on tough insects, others on softer insects.”

This study, having identified difference in jaw mechanics between different species of Clevosaurus provides a hypothesis as to why several species of Clevosaurus could co-exist in the same habitat.  Niche partitioning could have been taking place with each species avoiding competition by specialising in hunting and eating different types of prey.  As the data generated in this study is roughly comparable to what is known about the jaws of early mammaliaforms, it raises the intriguing prospect that the jaws may have been functionally similar and thus rhynochocephalians and early mammaliaforms were in direct competition with each other for food resources.

Everything Dinosaur acknowledges the assistance of a media release from the University of Bristol in the compilation of this article.

The scientific paper: “Biomechanical properties of the jaws of two species of Clevosaurus and a reanalysis of rhynchocephalian dentary morphospace” by Sofia A. V. Chambi‐Trowell, David I. Whiteside, Michael J. Benton and Emily J. Rayfield published in Palaeontology.

21 06, 2020

A Trip Down Memory Lane to the Late Jurassic

By | June 21st, 2020|Book Reviews, Dinosaur Fans, Everything Dinosaur News and Updates, Main Page, Photos|0 Comments

The Solnhofen Lagerstätte

Whilst looking for some information related to Triassic archosaurs, we came across a copy of a dinosaur book that was published forty-four years ago (1976).  Entitled “The evolution and ecology of the Dinosaurs”, this publication and the way it depicts the Dinosauria and their relatives might be very much out of date these days, but perusing the pages with their beautiful illustrations is still a very worthwhile activity.

The Front Cover of “The evolution and ecology of the Dinosaurs”

"The evolution and ecology of the Dinosaurs" by L. B. Halstead.

The front cover of “The evolution and ecology of the dinosaurs” by L. B. Halstead.

Picture Credit: Everything Dinosaur

Written by L. B. Halstead and illustrated by Giovanni Caselli, this dinosaur book was part of the Eurobook Ltd stable and was published by Book Club Associates.  We suspect that further editions were published but this is the only copy that we have in Everything Dinosaur’s library.

Five Chapters

Following a brief introduction, the book takes the reader through the evolution of the dinosaurs with one chapter dedicated to the origin of the Reptilia and the conquest of terrestrial environments.  A second chapter defines dinosaurs and sets out the “classical” view of the dinosaur family tree complete with a skilfully designed chronology of the main types of dinosaur and how they fit into the Reptilia and in broader terms, the evolution of the subphylum Vertebrata (the vertebrates).  The other three chapters are dedicated to the Triassic, Jurassic and the Cretaceous respectively.

One of the Beautiful Illustrations from the Dinosaur Book

A Late Jurassic lagoon.

An illustration from a dinosaur book, depicting the extensive lagoons of what was to become Germany in the Late Jurassic.

Picture Credit: Giovanni Caselli

In the foreground (above), a second species of Compsognathus – C. corallestris is shown.  It was thought that this theropod was adapted to a semi-aquatic existence.  The first fossils associated with Compsognathus were found in southern Germany in the 19th century.  A second, larger specimen associated with this genus was found in a lithographic limestone quarry near Nice in 1971.  This specimen was scientifically described and named in 1972 by Alain Bidar et al.  Although, the French specimen was found in association with lagoonal deposits and at the time it was described it was thought to be a separate species, C. corallestris is now thought to be a junior synonym of Compsognathus longiceps and most palaeontologists think that there is just one species associated with this genus.

The Complete Illustration of a Jurassic Lagoon from the Dinosaur Book

A Late Jurassic scene from Germany.

The full illustration depicting the lagoonal environment associated with the Solnhofen Lagerstätte.

Picture Credit: Everything Dinosaur

It was a pleasant experience to take a few minutes out of our busy day to take a trip down memory lane with this book about dinosaurs.

26 04, 2020

Out and About with the new for 2020 Mojo Fun Brontosaurus

By | April 26th, 2020|Adobe CS5, Dinosaur Fans, Everything Dinosaur Products, Main Page, Photos, Photos of Everything Dinosaur Products, Product Reviews|0 Comments

New for 2020 Mojo Fun Brontosaurus Model – Out and About with Brontosaurus

Everything Dinosaur is expecting deliveries of Papo prehistoric animals, Safari Ltd figures and CollectA models over the next few days.  All these figures have been put on stand-by, ready for team members to move into our warehouse – all part of our contingency plans put in place prior to the lockdown due to the COVID-19 outbreak.  By implementing good hygiene and ensuring social distancing is observed, our mail order operations can keep going.

However, despite our best efforts and all that planning, the production schedules for many new figures have had to be delayed.  For example, we are still awaiting the arrival of the new for 2020 Mojo Fun prehistoric animal and extinct figures.  We do have some production samples around the office, so we thought we would take advantage of the good weather to photograph one or two of these new models.

The New for 2020 Mojo Fun Brontosaurus Dinosaur Model

Mojo Fun Brontosaurus.

A Mojo Fun Brontosaurus.  This is the new for 2020 Mojo Fun Brontosaurus model.

Picture Credit: Everything Dinosaur

A More Muted Colour Scheme

The Mojo Fun Deluxe Brontosaurus has a much more muted colour scheme than the Diplodocus figure that was introduced in 2018.  The skin shows nice texturing and in order to reduce the length of the model as well as to animate the figure, the head and that thick sauropod neck is turned to the side and the tail curved round as if the dinosaur was just about to flick it out to deter a predator.

A Close-up Showing the Detailed Skin Texturing on the Neck of the Mojo Fun Deluxe Brontosaurus

Mojo Fun Brontosaurus dinosaur model.

A close-up view of the Mojo Fun Brontosaurus dinosaur.

Picture Credit: Everything Dinosaur

Following the extensive review of the Diplodocidae and the resurrection of the Brontosaurus genus, Mojo Fun is the latest manufacturer to introduce a replica of this iconic dinosaur.  A Brontosaurus model has been added recently by CollectA (2018), to their not for scale “Prehistoric Life” range.  It is likely that more Brontosaurus models will be made in the future.

To read Everything Dinosaur’s blog post about the revision of the diplodocids which led to the revival of the Brontosaurus genus: The Return of Brontosaurus.

A Closer View of the Anterior Portion of the Mojo Fun Brontosaurus Model

Mojo Fun Brontosaurus model.

The Mojo Fun Brontosaurus model.

Picture Credit: Everything Dinosaur

A Morrison Formation Favourite – Brontosaurus

Out and about with a Mojo Fun Brontosaurus model.

A Mojo Fun Brontosaurus dinosaur model on display.

Picture Credit: Everything Dinosaur

Mojo Fun Model Measurements

Team members have measured the figure.  It is approximately 22 cm long and the head is around 11 cm off the ground.  It is hoped that this new figure and the rest of the new for 2020 Mojo Fun prehistoric animal models will be in stock later on this year.  If we get any additional information with regards to a delivery date we will be sure to post up this news onto our various social media pages.

A Brontosaurus Attacked by Allosaurus (New for 2020 Mojo Fun Allosaurus Dinosaur Model)

Mojo Fun Allosaurus attacks the Mojo Fun Brontosaurus

A Mojo Fun Brontosaurus dinosaur model being attacked by the new for 2020 Mojo Fun Allosaurus figure.

Picture Credit: Everything Dinosaur

Sixteen New Mojo Fun Prehistoric and Extinct Models

Everything Dinosaur estimates that there are sixteen new Mojo Fun prehistoric animal models for 2020, including a new model of Allosaurus (pictured above).

To view the current range of Mojo prehistoric animals available from Everything Dinosaur: Mojo Fun Prehistoric and Extinct Models and Replicas.

22 03, 2020

We have Frogspawn in our Office Pond

By | March 22nd, 2020|Animal News Stories, Main Page, Photos|0 Comments

Frogspawn Laid on 19th March (2020)

These might be challenging times for us humans (Homo sapiens), what with all the concerns about the coronavirus outbreak, but at least for some animals it is business as usual.  We have frogspawn in our office pond!  The first eggs were laid in the early morning of the 19th March.  We normally have frogspawn around the third week of March in our part of the world, the date of laying can vary by a couple of weeks, depending on the weather and the type of winter we have had.  However, the spawning usually takes place around this time of year (third week of March).

The First Frogspawn Spotted in the Office Pond Early on the 19th March 2020

Frogspawn in the office pond at Everything Dinosaur (March 19th 2020).

The first batch of frogspawn laid in the office pond (March 19th 2020).  The photograph was taken a few minutes after 8am in the morning.  From the size of the frogspawn we think that these are the eggs from a single female and that they had only just been laid.

Picture Credit: Everything Dinosaur

Common Frog (Rana temporaria)

We have counted a total of seven frogs in the pond, the majority were males.  We tend to have the males arriving first and the females taking up residence a little time later (after all, the females tend to be pounced upon as soon as they enter the pond).  The frogs are all Common frogs (Rana temporaria), their name is a bit of a misnomer these days, as like many amphibians, they are becoming increasingly rare.

More Frogspawn was Laid that Morning (March 19th 2020)

Frogspawn spotted in the office pond - March 19th 2020.

More frogspawn laid on the morning of 19th March 2020.  Team members at Everything Dinosaur estimate that the egg masses represent the eggs from two or three females.  We shall continue to carefully monitor the pond (taking care not to disturb the frogs too much), to see if more eggs will be laid.

Picture Credit: Everything Dinosaur

As we cope with the current restrictions on our lives due to the coronavirus crisis, we will be able to observe how the tadpoles are getting on – something for us to think about in these challenging times.  At least the frogs are behaving as normal, for them at least, it is business as usual.

31 01, 2020

A Whale of a Time at the London Natural History Museum

By | January 31st, 2020|Animal News Stories, Main Page, Photos|0 Comments

Saying Hello to “Hope” the Blue Whale Exhibit

Another busy week for Everything Dinosaur team members.  A member of staff was at the London Natural History Museum recently, although they had a busy itinerary there was still time to enter the main gallery (the Hintze Hall) and to say hello to “Hope”, the enormous Blue Whale exhibit that replaced “Dippy” the Diplodocus in 2017.  Suspended overhead, dominating the refurbished gallery, the Blue Whale skeleton (Balaenoptera musculus), symbolises the Museum’s focus on conservation and supporting efforts to save natural habitats and wildlife.

The Spectacular “Hope” Blue Whale Exhibit in the Hintze Hall (London Natural History Museum)

Blue Whale exhibit (London Natural History Museum).

The beautiful Blue Whale skeleton exhibit dominating the Hintze Hall at the London Natural History Museum.

Picture Credit: Everything Dinosaur

The skeleton measures 25.2 metres in length, it weighs some 4.5 tonnes and consists of 221 individual bones.  Not all parts of the exhibit are real bone, some bones were missing from the right flipper and these have been replaced by 3-D printed mirror copies of the bones from the left flipper.  Seeing the Diplodocus exhibit in the main gallery was always a highlight of any visit to the Museum.  It became almost a ritual to say hello to “Dippy” on the way to a meeting or prior to visiting one of the various departments on site.

The Diplodocus exhibit was only a cast, a specimen that had been donated to the London Natural History Museum in 1905 by the Scottish-born billionaire Andrew Carnegie.  “Dippy” was installed into the Hintze Hall in 1979, but finally removed in January 2017 to be replaced by the Blue Whale exhibit.

We will have to get used to saying hello to “Hope” instead.

 

29 10, 2019

A Pine Cone Dinosaur

By | October 29th, 2019|Main Page, Photos|0 Comments

A Pine Cone Dinosaur

Here in the UK, it is definitely autumn.  British Summer Time (BST), has officially ended, the clocks went back an hour over the weekend and we have had our first frosts.  Still, team workers are snug in their offices working hard to prepare and pack orders for customers.  However, occasionally, just occasionally we get a little time to be creative and make something with a dinosaur or fossil motif.

Take for example this pine cone dinosaur that has been constructed.

A Pine Cone Dinosaur – a Pinoceratops Perhaps?

Pine cone dinosaur.

Making a horned dinosaur (ceratopsian) out of a pine cone.

Picture Credit: Everything Dinosaur

We used four acorns for the dinosaur’s limbs, the base of the head crest is the bottom of one pine cone, whilst the body is made from another pine cone.  To complete our dinosaur, we made a small head using an off-cut of cardboard and the large brow horns are also made from card too.  To finish our horned dinosaur, we wanted to add a small nose horn, but what to use, how about a pine nut, after all, it is in keeping with the rest of our prehistoric animal.

6 10, 2019

New Species of Crocodile Honours Researcher

By | October 6th, 2019|Animal News Stories, Geology, Main Page, Photos|0 Comments

Crocodylus halli – A New Species of Crocodile is Announced

The crocodile family has undergone yet another revision.  It seems that the Crocodylidae are a more specious family than previously thought.  The New Guinea Crocodile (Crocodylus novaeguineae), is actually two species and not one and the second species has been named Crocodylus halli after Philip Hall, a University of Florida researcher who sadly, passed away before his work on these three-metre-long reptiles could be completed.

A New Crocodile Species has been Discovered – Hall’s Crocodile (Crocodylus halli)

New crocodile species discovered.

A new crocodile species has been discovered.  The picture (above), shows Jen Brueggen, Park social media manager, researchers Caleb McMahan, Christopher Murray and John Brueggen, Park director, with a specimen of Crocodylus halli, that seems rather reluctant to pose for a photograph.

Picture Credit: Southeastern Louisiana University

Crocodile Nesting Behaviour Hinted at Different Species

The late scientist Philip Hall, noticed subtle differences in osteoderm patterns on the backs of crocodiles and in the nesting behaviours of crocodile populations in the north and the south of the island of New Guinea.  He speculated that there could be two species living on New Guinea, but unfortunately, he died before his research could be completed.  Southeastern Louisiana University Assistant Professor of Biology Christopher Murray and his co-author Caleb McMahan (Field Museum, Chicago), were inspired to continue this research and they have published their findings in the academic journal “Copeia”, the journal of the American Society of Ichthyologists and Herpetologists.

A chain of high hills and mountains known as the Central Highlands divides the island of New Guinea.  It is thought this geological feature was formed in the last 8 million years or so.  Geographically isolated crocodile populations, each living on different drainage basins that came about as a result of the uplift, have been identified as different species.

The Island of New Guinea 

Distribution of crocodile populations on New Guinea.

The Central Highlands of New Guinea permits two distinct drainage basins to form. This geographical barrier has led to the evolution of two distinct species of crocodile.

Picture Credit: Copeia/Murray and McMahan with additional annotation by Everything Dinosaur

The illustration of the island of New Guinea (above), shows the location of the Central Highlands and the red dots south of the mountain chain denote sampling areas for C. halli in the study, whilst the brown dots north of the chain indicate sampling sites for C. novaeguineae.

Careful analysis of museum specimens along with a study of the crocodiles kept in captivity at the St Augustine Alligator Zoological Park (Florida), confirmed the hypothesis.  Subtle differences in the shape of bones and the observed behaviour differences indicates the presence of two distinct species on the island.  This has been confirmed by molecular analysis.

Difference in the Shape of the Skull and Jaws

Comparing Crocodile Skulls from Papua New Guinea.

Dorsal view of skulls from  New Guinea crocodiles.  Crocodylus novaeguineae (left) with its extended maxilla and proportionately reduced postcranial elements compared with two examples of Crocodylus halli (middle and right).  In contrast, the C. halli skulls show much shorter maxillae and proportionately enlarged postcranial elements.

Picture Credit: Copeia/Murray and McMahan

The Importance of Museum Specimens

The researchers comment that this new insight into the Crocodylidae would not have been possible without access to the collections from numerous museums.  The museums involved in this research included The Field Museum (Chicago), the Smithsonian National Museum of Natural History, the Museum of Comparative Zoology at Harvard University, the American Museum of Natural History (New York), Queensland Museum, Louisiana State University Museum of Natural Science and the Florida Museum of Natural History.  The careful curation and collection of a large number of specimens permitted the scientists to build up a substantial database on crocodilian skull morphology that allowed them to tease out the subtle differences between the two species.

Crocodylus halli – Hall’s Crocodile

Newly described crocodile species from New Guinea Crocodylus halli.

One of the residents at the St. Augustine Alligator Farm Zoological Park – Crocodylus halli.

Picture Credit: Copeia/Murray and McMahan

Implications for Crocodile Conservation

Identifying a separate species has important implications for the conservation of both populations of crocodile.

Commenting on the significance of this discovery, Caleb McMahan stated:

“Now that we know the evolutionary history of these species, we need to re-inform the conservation status of them given that the distribution has changed and conservation threats are different in different areas.”

9 07, 2019

Wild Safari Prehistoric World Parasaurolophus

By | July 9th, 2019|Adobe CS5, Dinosaur Fans, Main Page, Photos, Photos of Everything Dinosaur Products|0 Comments

Wild Safari Prehistoric World Parasaurolophus

Safari Ltd have published a series of images depicting some of the latest introductions in the Wild Safari Prehistoric World model range.  Today, we feature the Parasaurolophus, a dinosaur that has been depicted several times over the history of Safari Ltd models.  The latest incarnation of Parasaurolophus, was introduced in 2017, one of thirteen prehistoric animal models launched by the U.S.-based company that year.

The Wild Safari Prehistoric World Parasaurolophus Dinosaur Model

Wild Safari Prehistoric World Parasaurolophus dinosaur model.

A pair of Parasaurolophus cooling off in the Late Cretaceous of North America.

Picture Credit: Safari Ltd/Everything Dinosaur

Parasaurolophus walkeri

Known from numerous very nearly complete and partial skeletons, Parasaurolophus was geographically widely distributed (Alberta to New Mexico – possibly), it is known from the Late Cretaceous (Campanian faunal stage), although there are some unverified reports that this dinosaur may have persisted into the Maastrichtian faunal stage of the Cretaceous.  It is easily recognisable for its long, backward pointing head crest.   Despite the amount of fossil material scientists have to study, the exact size of this herbivorous dinosaur remains open to speculation, with some estimates putting this dinosaur’s maximum length at more than ten metres.  Measurements of the femur (thigh bone), indicate that this duck-billed dinosaur may have weighed more than three tonnes.  Several species have been assigned to the Parasaurolophus genus, perhaps the best known of which is P. walkeri, mainly because this Parasaurolophus species had the more spectacular crest compared to other species in this genus.

Parasaurolophus walkeri – Scale Drawing

Scale drawing Parasaurolophus walkeri.

A crested, duck-billed dinosaur.  A scale drawing of the Late Cretaceous lamebeosaurine dinosaur Parasaurolophus walkeri.  Note the thick-set upper legs and the wide tail.  Recent studies indicate that this facultative biped was very robust.

Picture Credit: Everything Dinosaur

10 06, 2019

Jurassic June

By | June 10th, 2019|Dinosaur and Prehistoric Animal Drawings, Dinosaur Fans, Photos|0 Comments

Jurassic June – Favourite Artwork

Lots of things happening at Everything Dinosaur at the moment.  We have something like thirty new models coming into stock over the summer and early autumn, plus of course, we are busy with all our teaching activities and school visits.  However, there is time to post up one of our favourite pieces of prehistoric themed artwork in “Jurassic June”.

Amazing Jurassic June Artwork – Capturing Prehistoric Scenes

Artwork by Zallinger.

Beautiful and Detailed Drawings of Dinosaurs and other Prehistoric Animals.

Picture Credit: Everything Dinosaur (original artwork by Rudolph F. Zallinger)

“Dinosaurs and Other Prehistoric Reptiles”

The beautiful illustration (above), comes from one of our favourite dinosaur books, “Dinosaurs and Other Prehistoric Reptiles” written by Jane Werner Watson and illustrated by the amazingly talented Rudolph F. Zallinger.  First published in 1966 (we think this is correct), the office copy dates from the early 1970’s and is in pride of place on our office bookshelves.  Although this book is somewhat outdated in terms of its details and the dinosaurs themselves do not represent current scientific thinking, the illustrations of ancient prehistoric landscapes and the animals that inhabited them are simply stunning.

The illustration depicts a swift Ornitholestes hunting a pair of early birds, a scene depicting the Late Jurassic.  The artwork within this book, by Rudolph F. Zallinger, helped to capture the imaginations of countless children and to enthuse them about dinosaurs and life in the past.  Everything Dinosaur team members were no exception.

9 06, 2019

Ammonites Separating the Boys from the Girls

By | June 9th, 2019|Main Page, Photos, Photos/Pictures of Fossils|0 Comments

Male and Female Ammonites

The weather might be most unpleasant for much of the British Isles at the moment, but soon it will be the summer holidays and many of the beaches of Britain will be crowded by fossil hunters keen to add to their fossil collections.  At numerous sites, fossils of ammonites can be found.  The shells of these widespread, diverse and specious cephalopods adorn many amateur fossil collections.  Here at Everything Dinosaur, we have hundreds and hundreds of specimens.  Although, lots of people find ammonite fossils, in our experience few are aware of the amazing sexual dimorphism exhibited by the Subclass Ammonoidea.

Female Ammonites were Larger than Male Ammonites

Sexual dimorphism in ammonites.

Two ammonites from the same species but believed to represent a female (left) and the smaller male (right).

Picture Credit: Everything Dinosaur

The Macroconch and the Microconch

The fossilised shells of ammonites often preserve remarkable detail, but the size of the specimen found can also help to tell the boys from the girls.  It is believed that shell size can help scientists determine male and female specimens in some species of ammonite.  As far as we at Everything Dinosaur are aware, ammonites exhibited sexual dimorphism, that is, the females of a species grew to be much bigger than the males (see picture of ammonite fossil shells above).

The microconch (male) is smaller and wider, whilst the macroconch, believed to represent the female of the species is much larger, an adaptation to accommodate egg production.  This dimorphism is found to today in the close relative of ammonites – the nautilus.

Ammonite Fossil (Male)

Ammonite fossil - believed to be male.

A close view of what is believed to be a male ammonite.

Picture Credit: Everything Dinosaur

Some male and female ammonites of the same species had different sized and different shaped shells.  There is evidence to suggest that the in some species, the microconch, representing the male had long projections from the forward edge of the body chamber.  This could have helped to protect the animal, but they may have signalled maturity and fitness for breeding.  Perhaps these projections were used in intraspecific conflict over mate selection.

Most ammonite fossils found in the UK represent creatures that lived during the Jurassic, although a number of sites, particularly in southern England, such as the beaches around Folkestone in Kent, yield evidence of Cretaceous ammonites.  Most ammonite fossils found are relatively small with only a few specimens exceeding 25 centimetres in diameter, but fragments of the shells of much larger animals can still be found.

Ammonite Specimens on Display

Male and female ammonites.

A display from the National Museum of Wales (Cardiff) looking at male and female ammonites.

Picture Credit: Everything Dinosaur

Dangerous Cliffs

The recent heavy rain has led to a number of cliffs becoming unstable.  Everything Dinosaur has posted up helpful information and advice warning prospective fossil hunters to stay clear of cliffs.  Many cliffs have become saturated with water and the risk of substantial rock falls and landslides is high in many coastal locations.  Whether looking for ammonites, or indeed any other fossil for that matter, please take care, heed local warnings and don’t stray too close to cliffs, there are plenty of fossils to be found on the foreshore.

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