December, 2019 | Everything Dinosaur Blog

5 12, 2019

New Mojo Fun Prehistoric Life Dinosaur Models (Part 2)

By Mike|2024-01-06T11:01:45+00:00December 5th, 2019|Adobe CS5, Dinosaur Fans, Everything Dinosaur News and Updates, Everything Dinosaur Products, Main Page, Photos of Everything Dinosaur Products, Press Releases|1 Comment

New Mojo Fun Prehistoric Life Dinosaur Models (Part 2)

Yesterday, Everything Dinosaur introduced six of the twelve new for 2020 dinosaur models from Mojo Fun. In the second and final part of this series, we discuss the remaining prehistoric animal figures due out next year in the “Prehistoric Life” model range.

New for 2020 Mojo Fun Allosaurus Dinosaur Model

Picture credit: Everything Dinosaur

Mojo Fun Allosaurus Dinosaur Model

The 2020 Allosaurus model is a new sculpt, team members at Everything Dinosaur are not sure whether this new figure will replace the existing Allosaurus model in the Mojo Fun portfolio. The 2020 version has an articulated lower jaw and it is slightly longer than its predecessor. The scarlet hornlets over the eyes and the raised markings along the snout contrast nicely with the muted dark grey overtones of the head and the body. The Allosaurus is well-balanced and stable, thanks to the slightly oversized hind feet.

Mojo Fun New for 2020 Stegosaurus

Picture credit: Everything Dinosaur

Visit the Everything Dinosaur website: Everything Dinosaur.

Mojo Fun Stegosaurus

In yesterday’s post when we discussed the Ankylosaurus figure, a second armoured dinosaur for 2020 was mentioned. We can now reveal that this is a new Stegosaurus sculpt. Those famous plates running along the back are nicely shaped and carefully painted, these plates are stiff and not likely to be bent out of shape very easily. The skin texture is well done with plenty of creases and wrinkles and there is even texture on the underside of the feet! The posture also reflects a more modern interpretation than previous Stegosaurus figures.

Mojo Fun Models Reconstruct Life in the Late Jurassic of Western North America

New for 2020 the Mojo Fun Stegosaurus and Allosaurus. — *Mojo Fun Stegosaurus and Allosaurus. Two dinosaurs associated with the Upper Jurassic Morrison Formation of western North America.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

The New for 2020 Mandschurosaurus Dinosaur Model

Picture credit: Everything Dinosaur

Mandschurosaurus Dinosaur Model

Ninety years after this plant-eating hadrosaurid was first described, Mojo Fun are introducing a Mandschurosaurus dinosaur model to their “Prehistoric Life” model range. This Late Cretaceous, Chinese dinosaur might be regarded as “nomen dubium” by some scientists but there is nothing dubious about this figure, it has been skilfully crafted and beautifully painted.

The model is robust and sturdy and has a reassuring “solid” feel to it, the paint scheme is very striking with the brown combining well with the warm, apricot tones. There is certainly plenty of detail to admire, the definitive black beak and the deep base to the tail, along with our favourite little touch, the fold of skin under the neck. All in all, top marks for Mojo Fun for introducing a Mandschurosaurus into their product range.

Mojo Fun Tyrannosaurus rex Model (2020)

Mojo Fun T. rex (new for 2020). — *The Mojo Fun Tyrannosaurus rex dinosaur model (new for 2020).* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mojo Fun Tyrannosaurus rex

From one of the more obscure residents of the northern hemisphere in the Late Cretaceous to the most famous dinosaur of all. Mojo Fun will add a new model of T. rex to their range. This figure too is a new sculpt and it is very stable and well built. The jaw on our production figure does not open as wide as other models, but it opens wide enough to view the fleshy, muscular tongue, which has almost got a purple tinge to it. This is the largest T. rex figure made by Mojo Fun, it is some six centimetres longer than the 1/40th scale replica in this range. It stands well and we particularly like the black wash effect applied to the hind feet.

The Mojo Fun Triceratops Dinosaur Model (2020)

*The Mojo Fun new for 2020 Triceratops dinosaur model.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mojo Fun 2020 Triceratops Dinosaur Model

Bring out a new T. rex and a new version of Triceratops is sure to follow. Mojo Fun don’t disappoint with a Triceratops scheduled to be released next year. The figure is a colour variant on the existing Mojo Fun “large” Triceratops model, but the paint scheme has changed. The model has a muted look overall, but the weathered look on those impressive brow horns has been retained.

Triceratops Better Watch Out! There’s a New Mojo Fun T. rex Approaching

*The Mojo Fun Triceratops and the T. rex dinosaur model (2020). The Triceratops has fantastic skin texture, this can be clearly seen on the shoulders and forelimbs of the model in closer view.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mojo Fun Troodon (Troodontid) Model

Mojo Fun Troodon dinosaur model (2020) — *New for 2020 the Mojo Fun troodontid dinosaur model.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mojo Fun Troodon (Troodontid)

The final model that we will feature today, is a feathered dinosaur, it is a model of Troodon, a famous North American, Late Cretaceous member of the Theropoda that was originally named on the basis of a single fossil tooth associated with the Judith River Formation of Montana. The figure has been carefully sculpted to give the impression of a shaggy, feathery coat and in common with the rest of the new Mojo Fun releases the colour scheme is muted. The second toe of each foot is raised off the ground and the stiff, inflexible tail extends out behind the model and ends in a brown and cream coloured fan. The figure is well balanced and the feathers on the wings are beautifully marked. The Troodon figure has an articulated lower jaw.

Tale of the Tape

Mojo Fun Allosaurus – length 22 cm, height of the head 9 cm.
Mojo Fun Stegosaurus – length 19 cm.
The Mojo Fun Mandschurosaurus – length 24.5 cm.
Mojo Fun Tyrannosaurus rex – length 30 cm, height of the head 11.5 cm.
The Mojo Fun Triceratops – length 20 cm.
Mojo Fun Troodon (troodontid) – length 22 cm, height of head 9.5 cm.

To read the first part in this series: New Mojo Fun Dinosaur Models (Part 1).

To view the existing range of Mojo Fun models available from Everything Dinosaur: Mojo Fun Prehistoric and Extinct Models.

4 12, 2019

New Mojo Fun Prehistoric Life Dinosaur Models (Part 1)

By Mike|2024-01-06T08:22:06+00:00December 4th, 2019|Adobe CS5, Dinosaur Fans, Everything Dinosaur News and Updates, Everything Dinosaur Products, Main Page, Photos of Everything Dinosaur Products, Press Releases|0 Comments

New Mojo Fun “Prehistoric Life” Dinosaur Models (Part 1)

Mojo Fun is bringing out lots of new dinosaur models in 2020. There will be a total of twelve new dinosaurs added to the very successful Mojo Fun “Prehistoric Life” range next year. In the first of a two-part feature, Everything Dinosaur team members will be discussing these new models and showing photographs of the actual production figures.

The Mojo Fun Baryonyx Dinosaur Model (New for 2020)

New for 2020 Mojo Fun Prehistoric Life Baryonyx. — *The new for 2020 Mojo Fun Prehistoric Life Baryonyx dinosaur model. A geology ruler helps to provide scale.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mojo Fun Baryonyx Dinosaur Model

Mojo Fun will be replacing their 2018 “blue” Baryonyx figure with this new sculpt. The model reflects the more toned down approach to colouration that the company is employing with its new replicas and in our production figure the green paint on the topside of the model contrasts beautifully with the paler underside. It’s a classic case of countershading highlighted by the mottled black markings that run from the top of the neck down to the base of the tail and cover the flanks. The figure rests on its front claws, so stability is not an issue and Mojo Fun have added an articulated jaw.

“Bully for Brontosaurus” – New Mojo Fun Brontosaurus Model

New for 2020 the Mojo Fun Brontosaurus. — *The new for 2020 Mojo Fun Brontosaurus dinosaur model.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mojo Fun Brontosaurus Dinosaur Model

With the re-establishment of the Brontosaurus genus in 2015 following an extensive revision of diplodocid fossil material, manufacturers have been keen to add a Brontosaurus to their range. The Mojo Fun Brontosaurus opts for a more elephantine influenced colour scheme which contrasts nicely with their 2018 Diplodocus figure. The model shows lots of wrinkles and skin texture and the neck is quite robust which is typical of this genus compared to the more gracile Diplodocus. The Mojo Fun replica is sturdy and there is no noticeable flexibility in the neck or tail.

The tail itself has been skilfully modelled and the end is turning back on itself, this gives the impression of movement and will save a few cubic centimetres when it comes to boxing this model in readiness for sending out to customers. The teeth in our model, might be a shade too white, but the red eye markings are classy and the head shape reflects typical diplodocid morphology.

Mojo Fun Brachiosaurus – New for 2020

Mojo Fun Brachiosaurus dinosaur model (new for 2020). — *The new for 2020 Mojo Fun Brachiosaurus dinosaur model.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Visit the Everything Dinosaur website: Everything Dinosaur.

A New Brachiosaurus Dinosaur Model

Joining the Brontosaurus in 2020 is a new Brachiosaurus sculpt. The figure is a little larger than other brachiosaurid models in the Mojo Fun “Prehistoric Life” range and like the Brontosaurus it reflects a more muted colour scheme with effective countershading. It is pleasing to see plenty of texture and skin definition on the neck and the carefully painted eyes have a wet-look that provides realism. The skull is typical for models representing this genus and the body proportions, the relationship between the length of the neck and the length of the tail for example, reflect our views on the brachiosaurid material ascribed from the Morrison Formation of the United States.

New for 2020 Mojo Fun Mamenchisaurus

*The Mojo Fun Mamenchisaurus dinosaur model (new for 2020).* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Mamenchisaurus Model

Mojo Fun sauropod models are a bit like buses, you wait for ages for one to come along and then three come along together! The third in our new for 2020 Mojo Fun replicas is this beautifully painted model of Mamenchisaurus. It is a little larger than both the Brontosaurus and the Brachiosaurus figures, although none of these figures are regarded as being in scale, it is intriguing to consider that this figure represents one of the larger species assigned to the Mamenchisaurus genus. The subtle paint scheme is very effective and this model has a row of black scutes running from the base of the skull to around halfway along the tail.

This trio of figures from Mojo Fun demonstrates the diversity of the Sauropodomorpha during the Late Jurassic and it is always a pleasure to see a different type of long-necked dinosaur added to a manufacturer’s portfolio.

A Terrific Trio of Sauropods Coming in 2020

Mojo Fun Sauropods for 2020. — *Three new sauropods from Mojo Fun for 2020. Left Mamenchisaurus, centre, the new Brontosaurus and at the back the Mojo Fun Brachiosaurus model.* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Armoured Ankylosaurus

Two armoured dinosaurs are being added to the range next year (the second member of the Thyreophora will be featured in part 2), but first we focus on the new Ankylosaurus figure.

The New for 2020 Mojo Fun Ankylosaurus Dinosaur Model

*The Mojo Fun Ankylosaurus dinosaur model (new for 2020).* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

In contrast to the majority of the new models, the colour palette chosen for this new Ankylosaurus is more striking than the existing Ankylosaurus figure in the company’s model range. That formidable club tail is held out straight behind the body, which is anatomically correct and the bright, almost gold coloured osteoderms, spikes and scutes that run from the back of the skull to the tail reminded us of the depiction of Ankylosaurus is the ground-breaking BBC television series “Walking with Dinosaurs”. We compliment Mojo for the way in which they have maintained the level of detail even on the underside of the figure.

Mojo Fun New for 2020 Spinosaurus

Picture credit: Everything Dinosaur

Mojo Fun Spinosaurus Dinosaur Model

The final new for 2020 model that we will feature in the first part of our review is the Spinosaurus. This figure is much larger than the previous Spinosaurus in the Mojo Fun “Prehistoric Life” range and unlike its predecessor, this aquatic dinosaur is depicted in a quadrupedal pose. The head shows lots of detail and there is that distinctive kink in the front portion of the upper jaw, little horns over the eyes and a small crest in front of the orbits. The design team have taken care to examine the known cranial material associated with Spinosaurus aegyptiacus. The figure also has an articulated lower jaw.

There is a lot of detail in the skin texture and effective muscular definition on the hind legs. The colour scheme is intriguing, the figure is painted a metallic green with overtones of carmine red. Depending on the lighting conditions, the model takes on a completely different look, as shown in the picture below which compares it with the Mojo Fun Baryonyx figure.

A Pair of Spinosaurids – Baryonyx and Spinosaurus

Mojo Fun new for 2020 Spinosaurus and Baryonyx. — *The new for 2020 Mojo Fun Spinosaurus (back) and the Mojo Fun Baryonyx (front).* *Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Tale of the Tape

Mojo Fun Baryonyx – length 25 cm.
Mojo Fun Brontosaurus – length 22 cm, height of the head 11 cm.
The Mojo Fun Brachiosaurus – length 23 cm, height of the head 19 cm.
Mojo Fun Mamenchisaurus – length 26.5 cm, height of the head 19.5 cm.
The Mojo Fun Ankylosaurus – length 18.5 cm.
Mojo Fun Spinosaurus – length 28.5 cm, height of the sail 12.5 cm.

To view the range of Mojo Fun prehistoric animal figures available from Everything Dinosaur: Mojo Fun Prehistoric and Extinct Animals.

Part two, in which we show photographs of the final six new dinosaurs from Mojo Fun will be published tomorrow.

3 12, 2019

New Research Tells Teenage Tyrannosaurs Apart

By Mike|2024-01-06T07:59:35+00:00December 3rd, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Fossils From Alberta Help to Tell Teenage Tyrannosaurs Apart

It is often the case that a newly described fossil specimen only leads to confusion and controversy as its details are published. However, a reassessment of a partial skull of a juvenile dinosaur that had been attributed to the tyrannosaurine Daspletosaurus (Daspletosaurus torosus) has now been referred to Gorgosaurus libratus. The finding of a scrap of bone, a part of the skull (postorbital), discovered in the Dinosaur Park Formation of Alberta, was the key to unlocking a mystery when it came to deciphering the fossilised bones of young tyrannosaurids.

Thanks to this new research, identifying which fossils represent different tyrannosaurid species might just have become a little easier.

A Digital Reconstruction of the Skull Elements (TMP 1994.143.1.)

Picture credit: Voris et al/Scientific Reports

TMP 1994.143.1

The partial skull and jaws (specimen number TMP 1994.143.1.), comes from the Dinosaur Provincial Park Formation of southern Alberta. Although the fossil material was well preserved, the fossils were found in a jumbled and disarticulated state. The bones had also been distorted during burial and the fossilisation process (the red shaded elements in the picture above depict the bones affected). This distortion led to the bones becoming slightly wider, thus altering the dimensions of the fossil skull when it was reconstructed by scientists.

The skull length is around sixty-two centimetres whilst other skulls associated with Daspletosaurus torosus measure more than eighty-five centimetres in length, hence TMP 1994.143.1. was thought to represent a juvenile Daspletosaurus.

A Scale Drawing of an Adult Daspletosaurus

Drawing of Daspletosaurus. — *Daspletosaurus (D. torosus) is estimated to have been around 8-9 metres in length when fully grown. Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

Defining a Juvenile Dinosaur

As scientists have been able to work out the likely growth rates of different dinosaurs, so a definition of what makes a juvenile specimen has emerged. Lead author of the newly published paper, Jared Voris (University of Calgary), explained that juvenile dinosaurs were about half the body length of the largest adult animal known from that species. A juvenile Daspletosaurus would have been around 4 metres in length, the equivalent in age of a human teenager, but still a formidable predator, one best avoided by all but the largest herbivorous dinosaurs.

A Small Piece of Tyrannosaur Skull Bone – Changes Views

The discovery of a small, isolated tyrannosaurid postorbital bone found in the Dinosaur Park Formation led to a reassessment of TMP 1994.143.1. What was thought to represent the only known juvenile Daspletosaurus skull material has been assigned to the Gorgosaurus genus. The study reveals that previously unrecognised morphological differences exist between juvenile albertosaurines and tyrannosaurines and demonstrates that juvenile tyrannosaurids are more morphologically distinct than originally thought.

Previous issues associated with differentiating juveniles of these two clades were likely caused by the misidentification of TMP 1994.143.1 as a juvenile Daspletosaurus.

Views of the Postorbital Bone Assigned to a Juvenile Daspletosaurus

Juvenile Daspletosaurus postorbital bone. — Views of the juvenile Daspletosaurus postorbital (TMP 2013.18.11) with line drawings. Lateral view (a) with line drawing (c) and medial view (b) and accompanying line drawing (d). Note scale bars equal 5 cm.

Picture credit: Voris et al/Scientific Reports

Commenting on the significance of this new research, co-author Darla Zelenitsky (University of Calgary), explained that young Daspletosaurus specimens:

“Are now only represented by a few isolated bones instead of a nearly complete skull. Regardless, we still have been able to figure out the earlier growth stages in the life cycle of both tyrannosaurs, Gorgosaurus and Daspletosaurus.”

It seems that skull diagnostic features develop quite early in these types of theropod dinosaur, if this is the case, then distinguishing different Late Cretaceous tyrannosaurid species from even fragmentary fossil remains might just become a little easier in future.

The scientific paper: “Reassessment of a juvenile Daspletosaurus from the Late Cretaceous of Alberta, Canada with implications for the identification of immature tyrannosaurids” by Jared T. Voris, Darla K. Zelenitsky, François Therrien and Philip J. Currie published in Scientific Reports.

Visit the Everything Dinosaur website: Everything Dinosaur.

2 12, 2019

New Toothy Pterosaur Identified from the Afro-Arabian Continent

By Mike|2024-01-06T06:53:10+00:00December 2nd, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Mimodactylus libanensis Newly Described Lebanese Pterosaur

The Pterosauria were very probably ubiquitous over much of our planet during the Mesozoic. Once these flying reptiles had begun to diversify during the Late Triassic and into the Jurassic, these winged-wonders, the first vertebrates to master powered flight, would have spread far and wide. Trouble is, although palaeontologists have described more than 120 genera, our knowledge of the Pterosauria is limited and scientists rely on a few key deposits to provide them with the majority of specimens to study. Pterosaurs are now known from every continent, but surprisingly, very little material has been collected from Africa and the Arabian peninsula.

Writing in the academic journal “Scientific Reports”, a team of international scientists have announced the discovery of a Late Cretaceous pterosaur from Lebanon. Mimodactylus libanensis is the most complete pterosaur specimen to have been discovered from the Afro-Arabian continent. Intriguingly, the fossil material shows a strong taxonomic affinity with a genus known from China (Haopterus gracilis), together the pair form a new clade of toothy pterosaurs – the Mimodactylidae.

A Life Reconstruction of the Newly Described Pterosaur Mimodactylus libanensis

A life reconstruction of the pterosaur Mimodactylus. — A life reconstruction of Mimodactylus. This flying reptile lived on the western side of the Tethys Seaway, which divided Europe from North Africa. The sea was shallow with many reefs and lagoons, it was a spur of the mighty Tethys Ocean that stretched eastwards to south-eastern Asia.

Picture credit: Julius Csotonyi

Pterosaurs with Long, Narrow Wings

The fossil specimen comes from the famous Hjoûla Lagerstätte of Lebanon, a deposit famous for its beautifully preserved fossil fish, but tetrapod fossils are exceptionally rare. The nearly complete and articulated skeleton indicates that Mimodactylus had long, narrow wings and that it would have been well-adapted to soaring over the sea, in a similar way to extant frigate birds. As to what this pterosaur ate, that is open to speculation, but the robust, conical teeth located at the front of the jaws suggest a durophagus diet. Perhaps this pterosaur fed on molluscs and other shelled creatures.

A View of the Fossilised Remains of Mimodactylus libanensis

Mimodactylus fossil material and line drawings. — Mimodactylus views of the fossil material and accompanying line drawings. Photo (a) and drawing of the complete specimen. Close up (b) of scapula and coracoid whilst (c) shows detail of the wrist, showing the relation of the pteroid and the carpus. Detail (d) of the humerus. Note scale-bars, a: 50 mm; b-d: 10 mm.

Picture credit: Kellner et al/Scientific Reports

The Mimodactylidae

The single specimen represents a sub-adult, the wingspan is estimated to be around 1.3 metres, but in the absence of any fossil material representing an adult animal, the actual size of a fully grown Mimodactylus is not known. A phylogenetic analysis of the 95 million-year-old specimen suggests that Mimodactylus libanensis is closely related to pterosaurs from Asia and that with the taxon Haopterus gracilis, which is known from the Yixian Formation of Liaoning Province (north-eastern China), it forms a new clade of derived toothy pterosaurs, the Mimodactylidae.

One of the co-authors of the scientific paper, Michael Caldwell (University of Alberta), commented:

“This means that this Lebanese pterodactyloid was part of a radiation of flying reptiles living in and around and across the ancient Tethys Seaway, from China to a great reef system in what is today Lebanon.”

What’s in a Name?

The genus name is from the acronym (MIM), the Mineral Museum of Beirut in Lebanon, where the specimen is housed and the Greek “dactylos” meaning digit. The trivial epithet honours Lebanon where this rare specimen was found. An honourable mention to the anonymous philanthropist who acquired the fossil and ensured this important pterosaur was kept in Lebanon.

A Closer View of the Skull and Jaws of Mimodactylus libanensis

Mimodactylus skull and jaws. — *A close up view of the skull and the jaws of Mimodactylus (inset – close view of the conical teeth). Scale bars (a) 10 mm and (b) 1 mm.*

Picture credit: Kellner et al/Scientific Reports

The scientific paper: “First complete pterosaur from the Afro-Arabian continent: insight into pterodactyloid diversity” by Alexander W. A. Kellner, Michael W. Caldwell, Borja Holgado, Fabio M. Dalla Vecchia, Roy Nohra, Juliana M. Sayão and Philip J. Currie published in Scientific Reports.

The Everything Dinosaur website: Everything Dinosaur.

1 12, 2019

New Study Demonstrates Majungasaurus Replaced Teeth as Fast as Herbivorous Dinosaurs

By Mike|2024-01-06T06:39:10+00:00December 1st, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Majungasaurus – Elevated Tooth Replacement Rate

Scientists writing in the academic journal “PLOS One”, have really got their teeth into an aspect of dinosaur anatomy, that surprisingly has not attracted that much research to date. Dinosaurs replaced their teeth, as teeth were shed, perhaps when feeding or fighting, then replacements would erupt from the gumline permitting these reptiles to retain their toothy grins.

The speed of tooth replacement can provide palaeontologists with important information about feeding ecology. The fastest tooth replacement rates had been associated with herbivorous dinosaurs, the likes of the Ceratopsia and the hadrosaurids. After all, these plant-eaters fed on very coarse plant material so their teeth were subjected to plenty of wear and tear. In this new study, undertaken by researchers at Ohio University and Adelphi University (New York), tooth replacement rates for three carnivorous dinosaurs were calculated.

Surprisingly, Majungasaurus (M. crenatissimus), from the Late Cretaceous of Madagascar, had a much faster tooth replacement than the other theropods studied. Its tooth replacement rate puts it on a par with the rates associated with the horned dinosaurs and the duck-bills.

Computer Generated Images of the Skull of Majungasaurus

Majungasaurus skull diagram. — *A diagram showing the details of the skull of Majungasaurus. Views (A) left lateral, (B) buccal view, (C) dorsal view, (D) ventral view, (E) posterior view, (F) anterior view.*

Picture credit: Memoirs of the Society of Vertebrate Paleontology/Ohio University/from Sampson, S. D. and L. M. Witmer (2007)

Rapid Replacement of Majungasaurus Teeth

CT scans and detailed cross-sectional analysis were carried out on individual teeth and jaw elements associated with three theropod dinosaurs. These dinosaurs were the blunt-snouted, deep-skulled Majungasaurus along with Allosaurus and Ceratosaurus. High tooth replacement rates were identified in three genera, but the researchers concluded that Majungasaurus replaced its teeth much faster than either Allosaurus or Ceratosaurus. Majungasaurus would form a new tooth in each socket every fifty-six days or so, whilst Allosaurus and Ceratosaurus took in excess of a hundred days.

Lead author of the research, Michael D. D’Emic, (Adelphi University), explained the significance of this finding by commenting:

“This meant they [Majungasaurus] were wearing down their teeth quickly, possibly because they were gnawing on bones. There is independent evidence for this in the form of scratches and gouges that match the spacing and size of their teeth on a variety of bones — bones from animals that would have been their prey.”

An Accelerated Replacement Strategy

Assistant professor D’Emic went onto add that extant animals too, gnaw on bones, this is a way for them to get certain nutrients, but to feed like this requires exceptionally tough and strong teeth, Majungasaurus did not have teeth like that, so they evolved an accelerated replacement strategy to compensate.

Examining Tooth Replacement in Theropod Dinosaurs

Theropod dinosaurs in the study - Allosaurus, Ceratosaurus and Majungasaurus. — Studying tooth replacement in theropod dinosaurs. Three theropod genera were studied – Allosaurus, Ceratosaurus, Majungasaurus. Scale bar for (a), (b) and (c) equals 10 cm, the scale bar for (d), (e) and (f) equals 100 μm.

Picture credit: M. D. D’Emic et al/PLOS One with additional annotation by Everything Dinosaur

The picture (above), shows computer generated images of jaw elements of each dinosaur associated with the study (a) Allosaurus, (b) Ceratosaurus and (c) Majungasaurus. The images (d-f) show histological tooth sections which reveal incremental growth lines that can help to determine the individual age of teeth (d) Majungasaurus, (e) Ceratosaurus and (f) Allosaurus.

Using a statistical model to predict tooth age from tooth length measured in CT slices, replacement rates for these three genera are estimated at:

Majungasaurus 56 days
Allosaurus 104 days
Ceratosaurus 107 days

The rapid replacement rate recorded in Majungasaurus puts it on a par with living sharks and herbivorous dinosaurs.

Building on Research from Twenty Years Ago

This research builds on an earlier paper published twenty years ago, the authors of this new study suggest that with so many new dinosaurs being named and described over the last two decades or so, there is a lot of scope to build on the data collected so far and to provide further insights into dinosaur feeding ecology.

Michael D’Emic stated:

“I’m hoping this latest project spurs more people to study other species. I bet that it will reveal further surprises and hopefully that will lead to a better understanding of how dinosaurs evolved to be successful for so long.”

Now that less destructive forms of study are available to scientists, the analysis of tooth wear and the internal structures of dinosaur teeth will help to provide a clearer picture regarding dinosaur feeding behaviour and dietary preferences – now that’s something to smile about.

An Illustration of the Late Cretaceous Abelisaurid Majungasaurus (M. crenatissimus)

A drawing of Majungasaurus. — *An illustration of the abelisaurid Majungasaurus. Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

The scientific paper: “Evolution of high tooth replacement rates in theropod dinosaurs” by Michael D. D’Emic , Patrick M. O’Connor, Thomas R. Pascucci, Joanna N. Gavras, Elizabeth Mardakhayav and Eric K. Lund published in PLOS One.

The Everything Dinosaur website: Everything Dinosaur.