All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
21 04, 2018

Missing Link in Sea Turtle Evolution Identified

By | April 21st, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page|0 Comments

Peritresius martini – Missing Link in Sea Turtle Evolution

Tortoises, terrapins and turtles, collectively classified into the Order Testudines (sometimes referred to as the Chelonii), are a very ancient group of reptiles.  They were around before the crocodilians and the dinosaurs.  Surprisingly, not that much is known about the evolutionary origins of extant species, but newly published research by the University of Alabama at Birmingham, has identified an important missing link in the lineage leading to modern sea turtles.

A new species of Late Cretaceous sea turtle has been named and described in a paper published in the academic on-line journal “PLOS One”.  The turtle, which had a shell more than a metre in diameter, has been named Peritresius martini.  The turtle’s name honours amateur fossil collector and retired scientist George Martin, who discovered the specimen in Lowndes County, Alabama and donated the fossil to the Alabama Museum of Natural History (Tuscaloosa, Alabama).

The Known Fossil Material Ascribed to Peritresius martini

New species of Late Cretaceous sea turtle described.

The known fossil elements of P. martini with a line drawing showing their position in life.

Picture Credit: University of Alabama at Birmingham

In the picture (above), the known fossil elements are shown including elements from the carapace, the plastron and the pelvic girdle (centre image).  The fossil bones have been superimposed (in green) onto a line drawing showing a life reconstruction of the marine turtle.

Drew Gentry, lead author of the research and a PhD student at the University of Alabama at Birmingham stated:

“This discovery answers several important questions about the distribution and diversity of sea turtles during this period of time.  It provides further evidence that Alabama is one of the best places in the world to study some of the earliest ancestors of modern marine turtles.”

Alabama During the Late Cretaceous

The new species of sea turtle (P. martini), swam in the shallow waters off the coast of Appalachia between 73 and 70 million years ago.  It has been compared to the extant (Chelonia mydas), the green sea turtle, that can be found off the coast of Alabama today.

Alabama in the Late Cretaceous and Fossil Turtle Discoveries

Alabama and turtle fossil finds.

Alabama in the Late Cretaceous.  The picture above shows the biostratigraphy and the palaeobiogeography of the Late Cretaceous fossil turtle discoveries of North America.  Note P. martini is marked by the yellow star.

Picture Credit: PLOS One

Biostratigraphy and paleobiogeography of Late Cretaceous chelonioid species of North America.  Localities and taxon ranges for fossil occurrences key:

1).  Nichollsemys baieri – a sea turtle from the Bearpaw Formation of Canada dating from the Late Campanian.

2).  Porthochelys laticeps – a sea turtle from Kanas that lived during the Coniacian through into the Santonian faunal stages of the Late Cretaceous.

3).  Toxochelys latiremis  – a sea turtle known from western Kansas with a wide temporal distribution ranging from around 88 – 73 million years ago.

4).  Ctenochelys stenoporus – known from central Alabama.

5).  Prionochelys nauta – from the Mooreville Chalk Formation of Alabama.

6).  Toxochelys moorevillensis – from the Late Santonian and the Early Campanian which was named in 1953.

7).  Ctenochelys acris – closely related to C. stenoporus, graduate student Drew Gentry published a study that proved that C. acris was a valid species.  To read more about this research: Graduate Student Unlocks the Secrets of Sea Turtle Evolution

8).  Thinochelys lapisossea – from the Selma Formation of Alabama.

9). Zangerlchelys arkansaw –  a sea turtle from the Marlbrook Marl Formation of Arkansas.

10).  Peritresius martini – the newly described sea turtle from the study.

11).  Peritresius ornatus – a closely related marine turtle species to P. martini that was first named and described in the mid-19th Century.

12).  Euclastes wielandi – a primitive sea turtle dating from the Late Maastrichtian faunal stage of the Cretaceous.

13).  Catapleura repanda – a Late Cretaceous (Maastrichtian faunal stage), turtle associated with Greensand marine deposits of New Jersey.

Commenting on the contribution of George Martin, Drew Gentry said:

“Professional palaeontologists often spend a great deal of time in laboratories performing the in-depth research necessary to properly study extinct species.  Almost every palaeontologist would love to spend more time in the field looking for fossils.  But, without people like George Martin, many of the most significant fossil specimens ever found in Alabama would still be buried in the dirt.”

A Fortuitous Fossil Find

This important marine turtle fossil discovery happened by chance as George Martin explained;

“Finding this fossil turtle was largely happenstance as I stopped to look at the rock strata exposed by the stream.  I found a fragment of the turtle shell embedded in the marl and returned to the spot several times over the next year to recover fragments of the turtle as they were uncovered by the stream.”

However, without the skull and limb bones, the appearance and habits of P. martini can only be speculated upon.  The scientists have no information on what it fed upon, how it moved or whether this turtle was a creature of the coastal seas or deeper water.  The discovery of this new species of Peritresius helps to fill a gap in the Stem Cheloniidae, a group of ancient sea turtles that are related to the majority of sea turtles found today.

A Timeline of Turtle Evolution

A timeline of Testudine species from the Late Cretaceous to the present day.

Time-calibrated, strict consensus phylogeny of select fossil and extant Testudine species.  P. martini is highlighted by the purple star.

Picture Credit: PLOS One

Everything Dinosaur acknowledges the help of a University of Alabama at Birmingham press release in the compilation of this article.

21 04, 2018

Dinosaur and Fossil Themed Extension Resources

By | April 21st, 2018|Early Years Foundation Reception, General Teaching|Comments Off on Dinosaur and Fossil Themed Extension Resources

Dinosaur and Fossil Themed Extension Resources

Prior to starting a day of dinosaur workshops with Foundation Stage 2 children there was time to discuss the additional teaching resources that our dinosaur and fossil expert had brought with them.  When Everything Dinosaur team members visit schools, they always bring extra teaching aids to help support the school’s scheme of work.

Dinosaur Themed Teaching Resources for Schools

Dinosaur and fossil themed teaching resources.

Selected extension resources provided free of charge to help support Reception classes.

Picture Credit: Everything Dinosaur

Dinosaur and Fossil Themed Teaching Resources

Learning about dinosaurs is a great topic for Reception and Key Stage 1 children.  Many pupils already have quite a lot of pre-knowledge and learning about life in the past has plenty of touch points for cross-curricular activities, linking with literacy, numeracy, history, geography, exploring the properties of materials and introducing the idea of working scientifically.  The teaching resources we had prepared for the reception class included a dinosaur “hokey cokey”, a measuring exercise comparing the hands of the children to the footprints of dinosaurs and an exercise linked to exploring locations in the British Isles following the adventures of a baby Diplodocus.

Everything Dinosaur supplies numerous lesson plan ideas and teaching resources, these are available free and can be downloaded from our website.

To view the free downloadable teaching resources: Download Free Teaching Educational Resources from Everything Dinosaur

We also supplied a handy pronunciation guide as we do appreciate that some teachers and learning support assistants can struggle with all the long dinosaur and prehistoric animal names.  In addition, we also supplied some tridactyl (three-toed) dinosaur footprints that can be used in a simple writing exercise to help improve hand-eye co-ordination and motor skills.

A spokesperson from Everything Dinosaur commented:

“Learning about dinosaurs and fossils can provide a very rewarding and stimulating topic area, that dovetails nicely into a subject that many children are enthusiastic about.  Children as young as three, seem to pick up facts and awareness about dinosaurs and they love to demonstrate their knowledge and learning.”

We look forward to seeing pictures of the children’s work including their dinosaur drawings with lots of lovely labelling, a challenge we set the children during our dinosaur and fossil themed workshops.

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