Dinosaur relatives that live in Dorset
PUBLISHED: 11:34 20 February 2018 | UPDATED: 11:34 20 February 2018
As Dippy the Diplodocus takes up residence at Dorset County Museum, Catherine Bolado of Dorset Wildlife Trust reveals that some of Dippy’s relatives are still with us today
The Jurassic Coast is not only one of the most beautiful natural jewels in Dorset’s crown, but also one of the world’s most important geological sites – as identified by UNESCO who listed it as a natural World Heritage Site in 2001, the first in the UK. Its rock formations span three periods of Earth’s history: the Triassic, Jurassic and Cretaceous. You can walk through 185 million years along this coastline - from the distinctive red rocks of the Triassic era at Orcombe Point near Exmouth in East Devon, through to the younger Cretaceous chalk stacks of Old Harry Rocks at Swanage.
This area was once home to dinosaurs great and small, both on land and in the water. But do you know which of these ‘terrible lizards’ are still around today?
Feathered dinosaurs on the bird feeder
Seen any tiny dinosaurs on your bird table recently? Well, those adorable long-tailed tits tucking into the peanuts are descended from dinosaurs. Modern birds are related to theropod dinosaurs, which means ‘beast-footed.’ Theropods include the Tyrannosaurus-Rex (T-Rex). Birds evolved from small non-flying theropod dinosaurs and are avian dinosaurs, while T-Rex is a velociraptors (meaning ‘swift seizer’). These formidable dinosaurs had strong back legs for running and long claws for ripping prey, and they often hunted in packs.
Recent research has revealed that many theropod dinosaurs, including the non-avian ones, had feathers often in bright colours for visual displays. The largest known feathered dinosaur fossil is a 23-foot-long tyrannosaur found in China.
So when you’re admiring that robin, kingfisher or barn owl – remember its ancestors were around 167 million years ago and have resulted in the 10,000 plus varieties of birds of today.
A shared ammonite ancestor
Cephalopods such as the cuttlefish, squid and octopus which thrive in the waters off the Jurassic Coast today are living relatives of ammonites. These free-swimming mollusc were once abundant in the Jurassic seas off Dorset but became extinct along with the non-avian dinosaurs at the end of the Cretaceous period. Ammonites, which range from the size of a small button to a dustbin lid or larger, are one of the most commonly found fossils along the Jurassic Coast.
A very important shrew or two
Primitive mammals, the ancestors of all extinct and living mammals including humans, began to develop in the Triassic period (between 251 million and 199 million years ago). The following Jurassic period saw the development of therian mammals that give birth to live young rather than laying eggs. This large group divides into eutherians which became placental mammals such as badgers, foxes, water voles and us; and the metatherians which became the marsupials, who have their young in pouches such as kangaroos.
What would these mammal ancestors have looked like? Well, last year scientists from the University of Portsmouth were sifting through some rock samples collected at Durlston near Swanage when they identified the tiny teeth of two primitive shrew-like mammals. These distant eutherian relatives would have been scurrying around the feet of dinosaurs like Dippy that lived in this area 145 million years ago when it was lush tropical forest and lagoons. This very exciting Dorset find is the earliest fossils of the type of mammals from which humans are directly descended.
Sharks ancient and modern
Scientists believe that the first ancestors of sharks, skates and rays evolved some 400 million years ago - before the dinosaurs. In fact some fossils of ancient sharks bear a striking resemblance to species of shark found today. These ancient sharks could attain gigantic proportions such as the extinct megalodon (meaning ‘big tooth’) which could be 17 meters long - that’s twice the size sharks are today!
These ancient sharks shed their sharp teeth quite regularly, so you can sometimes find these when fossil hunting. The rest of the skeleton was composed of cartilage, so usually it’s only their teeth and fin spines that are preserved as fossils. Sharks probably outlasted the other giant marine reptiles of the Jurassic period because they are highly adaptable apex predators with seven senses.
During the Jurassic era there was a boom in the number and variety of shark species, forming the ancestral base of all the sharks, skates and rays we see off the Dorset coast today. One of our most common sharks, the small-spotted catshark (also known as the lesser-spotted dogfish), has ancestors going back even further to the Triassic period. You often find their egg cases - known as mermaid’s purses - washed up on Dorset’s beaches.
So, the next time you’re out for a stroll along the Jurassic Coast, remember you’re walking in the footsteps of some of your own ancestors. And maybe put out some extra seed for your garden birds too – after all you don’t want to upset the dinosaurs!
• What birds are up to in your garden this winter - Winter is an ideal time to observe the wild birds coming to feed in your garden and get to grips with the complex world of bird etiquette, says Sally Welbourn of Dorset Wildlife Trust