Ptychodontid Sharks Grew Big and Lived for a Long Time

Scientists from the University of Vienna have been able to determine the approximate age and to estimate the rate of growth of an extinct species of shark that lived around 85 million years ago.  In addition, the researchers, writing in the open access on-line journal PLOS One, have estimated that this ammonite crunching fish could have been in excess of seven metres in length, but even though it was a giant, this shark was not yet fully mature and still had some growing to do.

Much of what we know about prehistoric sharks comes from studies of their fossilised teeth.  However, apart from providing indications on size, taxonomy and potential diet, these teeth do not provide a great deal of information about the life and the age of the individual.  In contrast, the calcified vertebrae of elasmobranchs (sharks, skates and rays), specifically the centra, yield important information about ecological and biological traits.  Two fossil shark vertebrae assigned to the genus Ptychodus found in northern Spain, have enabled researchers to gain valuable information on the life of a single individual animal that lived during the Late Cretaceous.

Site Photographs of the Shark Vertebrae

Picture credit:  K. Oppermann

A Shark from Northern Spain

The fossil material consists of a portion of the spine representing five articulated and several disarticulated vertebral centra from a single animal.  The fossils were found in Upper Cretaceous strata around six miles west of the town of Santander in northern Spain, from a limestone exposure close to the village of Soto de la Marina.

The extensive marine sediments document much of the Late Cretaceous – ranging from early Santonian through to Maastrichtian-aged deposits.  The shark fossils come a bedding plane representing the earliest Santonian (circa 85 million years ago).  Although no teeth were found in association with the fossil material, the scientists have referred this material to the Ptychodus genus.  A relatively common and widespread genus that specialised in eating hard-shelled animals such as shellfish and ammonites (duraphagous diet).

Calculating the Size of the Prehistoric Shark

Previous research had shown a link between the total length attained for several living shark species and the diameter of the vertebral centra.  The linear regression used to calculate potential length was applied to these fossils and the scientists concluded that the shark was between 4.3 to 7.07 metres in length.

Estimating the Size of the Ptychodus spp.

Picture credit: Patrick L. Jambura (University of Vienna)

Intriguingly, the centra of sharks also preserve evidence of growth rate, from which an age range can be deduced, just as the rings on a tree stump can provide an indication of the tree’s age.  An analysis of the centra from two fossils indicated that this shark was around thirty years old when it died, quite an age for a shark, although what age some sharks species alive today can live to remains unknown.  Based on this study, the researchers propose that ptychodontid sharks grew very slowly, matured very late, but also showed high longevity and had the potential to reach huge body sizes.

Calcification Pattern on the Centra Can Provide an Indication of Growth Rate and Age

Picture credit: PLOS One (Jambura and Kriwet)

The scientific paper: “Articulated remains of the extinct shark Ptychodus (Elasmobranchii, Ptychodontidae) from the Upper Cretaceous of Spain provide insights into gigantism, growth rate and life history of ptychodontid sharks” by Patrick L. Jambura and Jürgen Kriwet published in PLOS One.

The Everything Dinosaur website: Everything Dinosaur.

Canadian Fossil Proves Origins of Mahogany Earlier Than Previously Thought

A fossilised fruit found on a beach in Canada has been identified as having come from a member of the mahogany tree family (Meliaceae).  This suggests that this commercially important hardwood evolved in the Cretaceous.   The fossil is some 15-20 million years older than any other fossil found that has been ascribed to the Meliaceae.  This type of tree would have been familiar to the dinosaurs.  Indigenous to the tropics of the Americas, the discovery of this fossil which dates between 79-72 million years ago (Campanian stage of the Late Cretaceous), will support palaeoclimate studies of high latitudes and permit palaeobotanists to better understand how modern tropical, angiosperm dominated ecosystems developed.

Manchestercarpa vancouverensis

The new species of Cretaceous-aged tree has been named Manchestercarpa vancouverensis.

Views of the Fossilised Mahogany Fruit (Manchestercarpa vancouverensis)

Picture credit: Brian Atkinson (University of Kansas)

The picture (above), shows cross-sectional views of the fruit and seeds of the newly described species of Cretaceous mahogany (Manchestercarpa vancouverensis).   The thick-walled outer skin of the fruit (endocarp) is identified along with the middle portion, the flesh of the fruit (mesocarp).  Evidence of seeds inside the fruit has also been found.

A Significant Fossil Discovery

Today, mahogany is a commercially very important hardwood, valued for its strength and beauty.  It is used in cabinet making, furniture and for creating musical instruments.  In the days of sailing ships, mahogany was much prized as this tough wood did not splinter as much as European timber when struck by a cannonball.  The UK is the world’s second largest importer of mahogany, after the United States.  To a palaeobotanist, finding a fossil that is reminiscent of fruit associated with these trees, lets them know that tropical forests similar to the ones we know today were in existence at the time of the dinosaurs.

Prior to this discovery, the oldest fossils attributed to the Meliaceae family date from the Palaeogene and Eocene such as those specimens found in the Green River Formation of Colorado.  However, the earliest previously recorded fossils associated with Melia are leaves and scientists have been reluctant to assign these fossils taxonomically.  The most diagnostic material are fossil fruits and these fossils have been found in several, geographically dispersed Eocene-aged deposits such as the London Clay and the Nanjemoy Formation of North America.

Geographically Widespread

It seems that in the past, these types of trees and therefore tropical forests were much more widespread than they are today.

Author of the scientific paper, published in the American Journal of Botany, University of Kansas researcher Brian Atkinson stated:

“For understanding when many of the different branches of the tree of life evolved, we’re primarily dependent on the fossil record.  In this case, Meliaceae, the mahogany family, is an ecologically and economically important group of trees.  A lot of researchers have used this group as a study system to better understand the evolution of tropical rainforests.  This work is the first definitive evidence that the tropically important trees were around during the Cretaceous period, when we first start to see the modernisation of ecosystems and modern groups of plants.”

The rock containing the fossilised fruit was found on a beach at Shelter Point, Vancouver (British Columbia), by fossil collector Graham Beard, the director of the Qualicum Beach Museum of Natural History.  The matrix in which the fossil was found is associated with the Spray Formation (Campanian faunal stage).   The genus name honours palaeobotanist Steve Manchester (University of Florida Museum of Natural History).  The species name honours the location of the fossil find.

Fossil Confirms a Cretaceous Origin for the Meliaceae

This paper clearly confirms a Cretaceous origin for Meliaceae and that important tropical families were present prior to the development of modern tropical ecosystems in the Cenozoic.

Graham Beard’s fossil hunting exploits have been featured in this blog before.  In 2011, Everything Dinosaur reported upon a paper that had been published naming a new species of Canadian pterosaur (Gwawinapterus beardi), that had been named in his honour.  A subsequent study published a year later, confirmed that the fossilised remains attributed to a late-surviving istiodactylid pterosaur actually represented the remains of a fish.  To the consternation of the academics associated with this study, it also turned out the Graham had been wrongly accredited with finding the fossil specimen.

To read more: Flying Reptile with “Piranha-like” Jaws the original article.

A second piece correcting the identity of the discoverer:  Mistake in Naming Pterosaur Fossil Discoverer.

The scientific paper: “Fossil evidence for a Cretaceous rise of the mahogany family” by Brian A. Atkinson published in the American Journal of Botany.

The Everything Dinosaur website: Everything Dinosaur.

Fossils Influence Mechanical Designs in the Aeronautical Industry

In vertebrates, powered flight has evolved independently in several groups, within the mammals there are the bats and within the Archosauria clade, other types of animal have evolved the ability to take to the air and to keep themselves airborne.  We have the birds, but also their close cousins the non-avian dinosaurs, as palaeontologists have discovered numerous examples of volant dinosaurs (Microraptor, Ambopteryx and Yi qi for instance).

There are also the pterosaurs, some of which were the largest flying animals to have ever existed with wingspans measuring more than ten metres across.  Engineers are now taking a serious look at some of the different types of wing morphology that have evolved.  The fossil record is helping to inspire new thinking in mechanical design.

The Recently Described Giant Azhdarchid Pterosaur Cryodrakon boreas Helping to Inspire New Ideas in Mechanical Design

Picture credit: David Maas

The Evolution of Different Solutions to the Problem of Sustained Powered Flight

Living birds and insects have been studied to help find solutions to aeronautical problems encountered when designing new planes, helicopters and unmanned aircraft such as drones.  However, a team of scientists including researchers from Bristol University, the Natural History Museum of Los Angeles County and Queen Mary University (London), have examined what the fossil record can teach us about powered flight.

Lead author of a recently published paper in “Trends in Ecology & Evolution”, Dr Elizabeth Martin-Silverstone, explained that there were a select few pterosaur fossils that provide dramatic insights into the anatomy and morphology of wing membranes, which could influence the thinking of aeronautical engineers as they contemplate concepts such as vertical take-off and landing capabilities in drones.

The post-doctoral researcher commented:

“There are two or three absolutely amazingly preserved pterosaur fossils that let you see the different layers within the wing membrane, giving us insight into its fibrous components.  Also, some fossils are preserved enough to show the wing attachments beneath the hip.  While you don’t know exactly the shape of the wing, by knowing the membrane attachments you can model the effectiveness of different wing shapes and determine which would have performed best in natural conditions.”

Beautifully Preserved Pterosaur Fossil Remains Helping to Inspire Engineers

Picture credit: Chinese Academy of Sciences/Journal of Vertebrate Palaeontology

Taking to the Air – A Big Leap Upwards

Taking to the air is a challenge in itself.  In the natural world, leaping or jumping to launch yourself into the air, using what is termed a ballistic launch is very common.  For larger birds, they require a running start in order to build up enough momentum before lift-off.

Pterosaurs, some of which weighed more than 250 kilograms and stood taller than a giraffe, may have developed a unique method of taking to the air from a stationary position.  For example, co-author Mike Habib (Natural History Museum of Los Angeles County), postulates that the wing membrane and powerful, robust associated muscle attachment within the wings allowed these flying reptiles to generate a high-powered leap off their elbows and wrists – providing the drive to enable them to become airborne.

Studying Pterosaur Fossils

The unique physiology of the Pterosauria, exquisitely laid out in some beautifully preserved fossil specimens might help engineers to overcome some of the launch problems associated with drones.  In essence, future biomechanical studies of long extinct creatures may influence the next generation of manned and unmanned aeronautical vehicles.

A number of different types of maniraptoran dinosaur came up with novel solutions when it came to flight. Whether or not animals such as the bizarre scansoriopterygid Yi qi were gliders or were capable of powered flight remains open to debate, but these bizarre evolutionary dead ends (extinct leaving no modern descendants), could help to drive innovative solutions to some of today’s aeronautical conundrums.

A Model of the Bizarre Scansoriopterygid Yi qi

The picture (above) shows a scansoriopterygid from the PNSO model range.

To view this range: PNSO Age of Dinosaurs.

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

The scientific paper: “Volant Fossil Vertebrates: Potential for Bioinspired Flight Technology” by Elizabeth Martin-Silverstone, Michael B. Habib and David W.E. Hone published in Trends in Ecology & Evolution.

The Everything Dinosaur website: Everything Dinosaur.

Dinosaur Eggs from the Late Triassic Reveal Their Contents

Researchers from the University of Witwatersrand (Johannesburg, South Africa), have utilised the high-powered and intense energy of the European Synchrotron Radiation Facility (ESRF), located at Grenoble in France to unscramble the embryonic development of dinosaurs.  The study, published in the journal “Scientific Reports”, demonstrates that dinosaur embryos show many similarities to the embryonic development of their living archosaurian relatives – birds and crocodiles.  In addition, the scientists found that in the dinosaur studied (the Sauropodomorpha Massospondylus carinatus), a set of simple teeth developed, in addition to the teeth the animal would have when it hatched.

Massospondylus carinatus

These simple teeth (null-generation teeth), were either reabsorbed into the jawbone or shed prior to the animal breaking out of the egg.  This anatomical trait is found in crocodiles and lizards such as geckos (Order Squamata).

A Computer Generated Image of a Massospondylus Embryo Showing the Skull Bones

Picture credit: Dr Kimberley Chapelle (University of Witwatersrand)

Lizards are not members of the Archosauria, they are not closely related to dinosaurs (nor to birds or crocodiles for that matter), this suggests that the production of null-generation teeth that are lost prior to hatching is an embryonic trait which is basal within the Class Reptilia and that, in essence, the embryonic developmental pattern in reptiles was established early in their evolutionary history.

Digitally Reconstructing the Skulls of Baby Dinosaurs

In the study, led by Dr Kimberley Chapelle and Professor Jonah Choiniere of the Evolutionary Studies Institute, based at the University of Witwatersrand, three-dimensional, computer generated images were created of the less than 2 cm long skulls of the embryonic dinosaurs.  The clutch of eggs was discovered in 1976 at a location within the Golden Gate Highlands National Park (Free State Province), the fossil specimens represent some of the oldest dinosaur eggs known to science.

The Clutch of Massospondylus Eggs Discovered in 1976 (Free State Province)

Picture credit: Brett Eloff

Amongst the Rarest of Dinosaur Fossils

The fossilised remains of dinosaur embryos are among the rarest of all vertebrate fossils.  However, if palaeontologists can study them, then they can provide unique insights into the development of baby dinosaurs and permit comparison with the development of living archosaurs such as birds and crocodiles.

The powerful X-rays generated by the synchrotron allowed the researchers to obtain extremely detailed images of the fragile contents of the eggs, in what is a non-destructive technique.  The study commenced in 2015, when the fossils were transported to the ESRF at Grenoble.  It took nearly three years to process all the data generated back at the University, but the work was worth it as the scientists were able to reconstruct the delicate, tiny skulls of the dinosaurs in exquisite detail.

The fossil specimens were scanned at an unprecedented level of detail, the team were able to define and map individual cells within the fossilised bone.

Views from Various Angles of the Tiny Skull of a Massospondylus Embryo

Picture credit: University of Witwatersrand/Scientific Reports

Working Out the Developmental Age of the Dinosaur Embryos

It had been thought that the fossilised Massospondylus eggs represented a clutch that had perished just prior to hatching.  An analysis of the state of the skull bones and direct comparison with the development stages of crocodile, chicken, turtle and lizard embryos revealed that the Massospondylus embryos were much younger than previously thought.  These dinosaur babies were only 60% of the way through their incubation.  This makes them some of the ontogenetically youngest dinosaur embryos known.  All other dinosaur embryos in the literature with ontogenetic age estimates are believed to represent dinosaurs in the last third of their development in the egg or close to hatching.

Hatching Massospondylus Dinosaurs in the Late Triassic of South Africa

Picture credit: Julius Csotonyi

The Discovery of Null-generation Teeth in Dinosaur Embryos

Furthermore, the researchers discovered that each tiny embryo had two types of teeth preserved in its developing jaws.  One set was very similar to the teeth associated with Massospondylus adults, the second set consisted of tiny, very simple triangular teeth that were either reabsorbed into the jaw or shed prior to hatching.  These types of teeth are referred to as null-generation teeth and they are found in crocodilians and some types of extant lizard embryos such as geckos.

An Illustration of the Tooth Crowns of an Adult Massospondylus

Picture credit: Everything Dinosaur from Gow et al (University of Witwatersrand)

Commenting on the discovery of null-generation teeth in the jaws of the dinosaur embryos, lead author, Dr Chapelle stated:

“I was really surprised to find that these embryos not only had teeth, but had two types of teeth.  The teeth are so tiny, they range from 0.4 to 0.7 mm wide.  That’s smaller than the tip of a toothpick!”

The scientists conclude that dinosaurs developed in their eggs in very similar ways as extant archosaurs, so what we know about the development of birds and crocodiles in the egg can be confidently applied to extinct archosaurs such as dinosaurs and pterosaurs too.  The development traits shared with members of the Squamata Order (lizards and snakes) would permit these findings to be applied generally to a much wider variety of extinct reptiles, such as those assigned to the Lepidosauria clade, the sister clade to the Archosauria, reptiles on a different branch of the Reptilia family tree.

Synchrotron Analysis Likely to Lead to Further Insights into Dinosaur Development

The research team hope to utilise the thousands of scans they have amassed to better understand the post-cranial development of sauropod dinosaurs.  They will be examining the rest of the skeleton of the Massospondylus embryos to see if this dinosaur shares similarities in development with extant archosaurs.  The scientists hope to shed further light on how these dinosaurs moved about when they first emerged from the nest.  Palaeontologists think that these types of dinosaurs hatched as bipeds before adopting a quadrupedal stance as these animals grew and matured.

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

The scientific paper: “Conserved in-ovo cranial ossification sequences of extant saurians allow estimation of embryonic dinosaur developmental stages” by Kimberley E. J. Chapelle, Vincent Fernandez and Jonah N. Choiniere published in Scientific Reports.

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