Sunday, June 23, 2019

Alanqa: Beast of the Week

Today we will be looking at an interesting pterosaur, Alanqa saharica!

Alanqa was a pterosaur that lived in what is now Morocco in Northern Africa, during the late Cretaceous Period, about 95 million years ago.  It was a relatively large pterosaur, with an estimated wingspan of up to twenty feet in the largest known individual.  The genus name translates to "phoenix"in Arabic in reference to the mythical bird.  When alive, Alanqa was most likely a meat eater.

Alanqa saharica life reconstruction in watercolors by Christopher DiPiazza.

Alanqa isn't known from too much fossil material, mostly beak and a vertebrae, but judging by these pieces, and comparing them with the proportions of other more completely known pterosaurs that were related to Alanqa, we can get a decent estimate of its overall size.  Alanqa was a member of the Azhdarchid family of pterosaurs.  Azhdarchids were primarily dominant during the Late Cretaceous and produced the largest animals to fly of all time, let alone the largest pterosaurs.  They are characterized by having proportionally huge skulls (longer than their torsos) with long tapering beaks devoid of teeth.  Many also had extremely long, but not very flexible, necks.  Azhdarchids are also thought to have been comfortable walking on land, even though evidence shows they could fly very well and for long distances, too.  A modern analog that is often made for them is today's storks and herons. (Although it is important to note that birds are NOT the same as pterosaurs.  They are purely convergent to each other.)  The extremely large Quetzalcoatlus, is the most well-known member of this family.

Part of Alanqa's beak.  Image from Ibrahim's 2010 paper.

The front of Alanqa's beak was narrow and pointed, like an extremely large pair of tweezers, great for targeting and plucking prey out of specific places, which typical for azhdarchids.  However, farther back in Alanqa's jaws were protrusions growing from the upper and lower parts of the beak, that would come together as the jaws closed.  It reminds me of the tool used to crack lobster shells, to be honest, and this very well may be what these unique adaptations were used for!  Alanqa very well may have been a specialist in eating prey with shells, like crustaceans, mollusks, and maybe even turtles?  It's also a possibility that Alanqa was an efficient scavenger and used these bony structures to crack open bones to get to the marrow inside?  I can imagine Alanqa wading around in shallow water with the narrow tip of its beak submerged, moving from side to side or probing into the mud as it uses its sense of touch to scan for any hiding prey.  When it finds something it grabs it with the tweezer-like front of its jaws then cocks its head back to maneuver the food item to the back, where it is cracked to pieces and swallowed!  This is all just speculation, of course.  But the fact of the matter is Alanqa did have a cool, unique adaptation of some kind in the back of its jaws.  We may never know for sure its purpose!

This is basically Alanqa's face...just tiny and made of metal.

That is all for this week!  As always feel free to comment below!

References

Ibrahim, Nizar; Unwin, David M; Martill, David M; Baidder, Lahssen; Zouhri, Samir (2010). "A New Pterosaur (Pterodactyloidea: Azhdarchidae) from the Upper Cretaceous of Morocco". PLoS ONE. 5 (5): e10875.


Martill, David M; Ibrahim, Nizar (2015). "An unusual modification of the jaws in cf. Alanqa, a mid-Cretaceous azhdarchid pterosaur from the Kem Kem beds of Morocco". Cretaceous Research. 53: 59.

Witton, Mark P.; Habib, Michael B.; Laudet, Vincent (15 November 2010). "On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness". PLoS ONE5 (11): e13982. 


Monday, June 3, 2019

Dakosaurus: Beast of the Week

You may know that we have reviewed a Godzilla dinosaur on here before.  This week we will be looking at yet another prehistoric beast with connections to the "King of the Monsters."  Check out Dakosaurus andiniensis!

Dakosaurus andiniensis lived in the oceans that once covered what is now Argentina during the Late Jurassic to the Early Cretaceous, between 145 and 140 million years ago.  Dakosaurus was a meat-eater in life, and measured about fifteen feet long from snout to tail.  The genus name, Dakosaurus, translates to "biter lizard/reptile" in reference to the creature's formidable teeth.  There are actually a few species within the Dakosaurus genus, but I want to focus specifically on the species, Dakosaurus andiniensis.  

Dakosaurus andiniensis by Christopher DiPiazza.

Dakosaurus was an extinct genus of crocodilian that belonged to the family called Metriorhynchidae.  Metriorhynchids were prehistoric crocodiles that were specially adapted to living in the ocean during the middle Jurassic through the early Cretaceous periods.  Their limbs were like flippers and their flattened tails even independently evolved flukes like those of sharks, dolphins, and their fellow reptiles, the ichthyosaurs and mosasaurs.

Fossilized skull of Dakosaurus andiniensis.  It looks mean!

Dakosaurus andiniensis had a uniquely short snout compared to the other species within its genus, giving it a particularly menacing look, to the scientists who studied it.  It is because of this unusually short, and boxy face, that this species of Dakosaurus was nicknamed "Godzilla" among the scientists who worked with it.

Dakosaurus' teeth were unique in that they were both laterally compressed and serrated.  This is a feature more commonly seen in certain kinds of meat-eating dinosaurs.  In fact, when the isolated teeth of Dakosaurus were first discovered, they were initially believed to have been from a Megalosaurus, not a crocodile.  The skull of Dakosaurus had openings towards the back, called fenestrae, that would have anchored powerful jaw muscles in life.  This, combined with the fact that its teeth were deeply rooted within the jaws, means that Dakosaurus would have been able to bite down with extreme force.  It is likely that an adult Dakosaurus would have been a top predator and was able to hunt most other animals it shared its habitat with, including other marine reptiles. 

Nobody is exactly sure how Dakosaurus would have reproduced.  There is specific fossil evidence that other prehistoric marine reptiles, like mosasaurs and ichthyosaurs, gave birth to live young in the water.   Dakosaurus' group, the crocodilians, however, only lay eggs in nests, however.  In fact, even broadening this group to all of archosauria, which includes crocodilians, in addition to dinosaurs and several other reptile groups, all we know of is egg-laying so far.  Going off this information alone, using closest relatives as a reference, Dakosaurus would have needed to haul out on land to lay its eggs.  However, a study looking at the anatomy of a more completely known metriorhynchid showed that the anatomy of the pelvis was more similar to that of other kinds of marine reptiles that we know gave birth to live young.  Despite that all known archosaurs lay eggs, it wouldn't be unheard of for one group of marine crocodilians to have evolved live birth, since we already can confirm it has happened multiple independent times in other groups of marine reptiles.

That is all for this week!  As always feel free to comment below.

References

Gasparini Z, Pol D, Spalletti LA. 2006. An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia. Science 311: 70-73.

Herrera, Y.; Fernandez, M.S.; Lamas, S.G.; Campos, L.; Talevi, M.; Gasparini, Z. (2017). "Morphology of the sacral region and reproductive strategies of Metriorhynchidae: a counter-inductive approach"Earth and Environmental Science Transactions of the Royal Society of Edinburgh: 1–9. 

Vignaud P, Gasparini ZB. 1996. New Dakosaurus (Crocodylomorpha, Thalattosuchia) from the Upper Jurassic of Argentina. Comptes Rendus de l'Académie des Sciences, Paris, 2 322: 245-250.