Did Birds out compete the Pterosaurs and force them to Extinction?

We have been recently reviewing some papers on Late Cretaceous pterosaurs written by Phil Currie and Stephen Godfrey.  The papers refer to the examination of flying reptile finds in the Dinosaur Park Formation (DPF) of Alberta, Canada.  Phil is the curator of Dinosaurs at the nearby Royal Tyrrell museum and Stephen works in the department of Palaeontology at the Calvert Marine museum.  Much of these authors work has been condensed and reproduced in the excellent volume “Dinosaur Provincial Park”.  This provides a review of the finds from this area and attempts to reconstruct the ecosystem that existed in this part of the world during the Campanian (rocks aged between 76.5 mya and 74.8 mya in the DPF).

Pterosaurs

Despite this being an area rich in fossils, there are very few remains of pterosaurs. Pterosaur bones are thin-walled and full of air cavities. This makes them light, ideal for flying creatures, however, they do not preserve very well.   The fossil record for pterosaurs from this region is poor and only a few isolated large bones such as femurs, tibias (leg bones); and an ulna (arm bone) have been found, plus some phalanxes.  The phalanx bones are the digits and in the case of flying reptiles these formed the wings.

From the limited evidence the scientists have been able to note that the vast majority of the remains seem to belong to a group of pterosaurs called azhdarchids.  These were the extremely large flying reptiles, with long necks, rounded neck vertebrae and relatively long skulls.  The largest flying reptile known – Quetzalcoatlus belonged to this family – the Azhdarchidae.

For a scale model of Quetzalcoatlus, the largest flying reptile yet described:

Pterosaur Models etc: Dinosaur and Prehistoric Animal Models.

End of the Cretaceous Flying Reptiles

It seems that the only flying reptiles left at the end of the Cretaceous were the extremely large, soaring types.  We still don’t know how these animals lived, perhaps since many of the fossils have been found in marine sediments they were ocean going fish eaters that roosted on the tops of cliffs, like modern day gannets.  It has even been suggested that Quetzalcoatlus was a specialist; feeding on crabs and other burrowing shellfish, using its long-snout to probe in the mud a bit like an oyster-catcher.

No skulls are known from the DPF so identification is difficult but it has been speculated that some of the remains belonged to Quetzalcoatlus northropi, the biggest pterosaur so far described.  This would extend this animal’s range from Texas right up to northern Canada.

A Scale Drawing of Quetzalcoatlus northropi

Drawing courtesy of Everything Dinosaur

The Dinosaur Park Formation (DPF)

The DPF has also provided evidence of birds, although once again the fossil record is poor.  Post cranial bones indicate that there might have been birds as big as modern hawks present in the Park area at the end of the Cretaceous.  At least three types of neornithine birds have been reported.  Neornithines have saddle shaped, articulating faces on their neck vertebra and usually lack teeth.  These are effectively modern birds.  As feathers tend to function better than flaps of skin, perhaps the birds dominated all the other aerial niches in the ecosystem and only the large soaring pterosaurs were left.

Birds do seem to have diversified very rapidly during the Cretaceous many modern genera that we would easily recognise were around in the last years of the dinosaurs.  Evidence has been uncovered for owls, rails, cormorants and tern-like sea birds.  Perhaps the rapidly expanding and diverse bird population led to the demise of the smaller pterosaurs.

To read an article from 2019 about a huge azhdarchid pterosaur discovered in Canada: The First Pterosaur Unique to Canada.

Tyrannosaurus rex is still Scary say Chinese Youngsters

Young residents of Shanghai have been given a scare by a Tyrannosaurus rex that has taken up residence in the city.  It may be rather surprising to find a T. rex in Shanghai, after all as far as palaeontologists know Tyrannosaurus rex lived in North America and it never got as far as eastern China.  Asia was the domain of an equally fierce Tyrannosaur called Tarbosaurus “alarming reptile” a close cousin of the more famous T. rex.

However, a local company wanting to commemorate the opening of new premises commissioned a 5 metre long statue of T. rex and placed it on their rooftop.  Local residents have objected claiming that the statue of T. rex in a typical pose (mouth open, showing huge teeth), frightens children.

Reluctantly, the company has agreed to remove the statue, but it has been given a stay of execution by the civic authorities, permitting T. rex to continue to look down on the locals – at least until the new premises are officially opened on August 8th.

After this date, either the statue will find a new home, or once again Tyrannosaurus rex will face extinction.

In reality, Tyrannosaurs could hardly be described as obvious candidates to have their features immortalised in a sculpture.  These animals (like most super-predators today) lived short, violent lives.  Tyrannosaurs would have been extremely unpleasant creatures to come across.  As well as the prospect of being treated like a mid-morning snack, the smell from a recent kill would probably still hang around them and if you got close enough to smell the breath of a T. rex (something we would not recommend), the stench would be most unpleasant.  T. rex most probably had a bacterial bite, meat would remain in the jaws and attract bacteria and other unpleasant pathogens.  When T. rex bit into an animal, the bite may not prove fatal but the injection of all the nasty little bugs and diseases into the unfortunate animal could well have weakened it to the point where it would eventually collapse.  Leaving the Tyrannosaur to simply follow its victim until it finally went down.  Komodo dragons have a similar hunting strategy, although recent research has shown that these giant monitor lizards are actually venomous.

Evidence from the fossils indicate that Tyrannosaurus would carry a number of injuries and would most certainly have been scarred, so they would not have been pleasant to look at.

“Stan” the gracile T. rex discovered in 1992 shows evidence of a number of serious injuries, which would not have given this particular dinosaur much chance of winning a beauty pageant.  For example, part of the postorbital and squamosal region of the skull (the back of the head) had been bitten off.  Remarkably, as there are signs of healing revealed in close analysis of the fossil bones, “Stan” survived this traumatic injury.

Slightly concerning is that Stan was about 40 feet long and weighed in around 5 Tonnes.  What kind of animal could have inflicted this sort of damage on a 40 foot Tyrannosaur?

Scientists know of only one animal capable of biting out chunks like this – another probably larger T. rex!

Evidence from their fossils, show that these animals lived short and violent lives.  Fighting prey and fighting rival Tyrannosaurs possibly over food, territory and mates.  For sure the big theropods may not have been much in the good looks stakes but they certainly still hold our fascination.  Long after the likes of Marilyn Monroe have faded from our collective memory people will still queue to catch a glimpse into the lives of these ancient reptiles.

Typical model of Tyrannosaurus rex in aggressive pose:

A T. rex Dinosaur Model

Fearsome dinosaur 1:40 scale figure.

Dinosaur Toys for Boys and Girls: Dinosaur and Prehistoric Animal Models.