Eocursor: Prehistoric Beast of the Week

This week we are going to check out a little dinosaur that gives us insight into the origins of some of the most iconic dinosaurs, Eocursor parvus!  

Eocursor translates to "Dawn Runner" because it was a very early dinosaur and its extremely long legs show us that it was probably a fast runner.  From snout to tail it only measured about 3 feet (roughly 1m) and was a plant-eater.  It lived about 210 million years ago in what is now South Africa and was discovered in the 1990s but wasn't formally described until 2007.

Watercolor life reconstruction of Eocursor by Christopher DiPiazza.

Eocursor was tiny and had no special armor, horns, spikes, large teeth or anything else that some other extinct dinosaurs had that would make it formidable but it is nonetheless an extremely important discovery.  This is because most other dinosaur we know of from the Triassic are either some sort of theropod, like Coelophysis or a prosauropod, like Plateosaurus.  Very rarely does anyone find a dinosaur like Eocursor which is in the same group as and likely the ancestor of the plant-eating, beaked dinosaurs like ceratopsians, thyreophorans and ornithopods.  We call this group the ornithischian dinosaurs or "bird hipped dinosaurs" (ironic because it's the other saurischian "lizard hipped" theropods that were actually directly related to birds).  It may not look like much, but Eocursor's lineage would evolve into some of the most successful and widespread dinosaurs of the Mesozoic!

Eocursor parvus bones

Like I said before, Eocursor had extremely long legs which would have come in handy(or leggy HA!) when avoiding all those hungry meat-eating theropods and crocodilomorphs of its time.  We can tell this because its tibia(lower leg bone right below the knee) was much longer than its femur (thigh bone) which is a characteristic of swift-runners.  It also would have had strong arms with five grasping fingers on each hand.  This might have aided it when foraging for plants to eat.  Its head was small and possessed small teeth that look like they would have been suitable for cutting leaves and other such plant material.  Even thought the top of its skull was never discovered, I would be willing to bet Eocursor also had large eyes, which is a trait common in small, fast-moving, plant-eating dinosaurs.

References

Butler, Richard J.; Roger M. H. Smith and David B. Norman (2007). "A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia". Proceedings of the Royal Society B: Biological Sciences 274 (1621): 2041. 

Gongshuilong: Beast of the Week

 Today we're checking out a recently described hadrosaur with a unique look, Gongshuilong fanwei!

Gongshuilong lived in what is now eastern China, during the late Cretaceous period, between 68 and 66 million years ago.  From beak to tail it measured about 23 feet (7m) long and would have been a plant-eater when alive.  The genus name translates from Mandarin to "Gong River Dragon" in reference to the Gong River near where its bones were discovered.

Gongshuilong life reconstruction in watercolors by Christopher DiPiazza.

Gongshuilong was a member of the hadrosaurid ("duck- billed") family of dinosaurs.  More specifically it was a saurolophine hadrosaur, which is the group that had broader bills and sometimes had crests made of solid bone structures on their heads.  Maiasaura and Probrachylophosaurus are two examples of close relatives.  Like its relatives, Gongshuilong would have been able to walk on all four legs or just its hind legs if it wanted to.  Its claws would have been hoof-like and the middle three fingers of each hand would have been fused together into a mitt, with one single hoof-like claw on the tip of them.  Like all members of its family it would have possessed a broad beak in the front of its jaws, backed up by rows of small teeth packed together to form what are referred to as "dental batteries".  These teeth were ideal for chewing up tough plants.

Photo of some of Gonghsuilong's bones, zooming in on the tall neural arches on the tail.  Image from the paper by Yao et al. listed below.

What makes Gongshuilong unusual for a hadrosaur is the fact that it had a display structure on its tail, in the form of a tall sail made up of elongated neural arches.  This would have given it a unique profile for a dinosaur, which makes me think of some living species of lizards which also sport similar structures on their tails for display within the species.  (Spinosaurus funnily enough independently had something similar)  It is likely Gongshuilong was doing something similar with its tail, possibly signaling to members of the same species for mating displays or to intimidate rivals.  Perhaps females possessed smaller sails than males?  We would need to find more fossils to have a better idea for sure.  

References

Ibrahim, Nizar; Maganuco, Simone; Dal Sasso, Cristiano; Fabbri, Matteo; Auditore, Marco; Bindellini, Gabriele; Martill, David M.; Zouhri, Samir; Mattarelli, Diego A.; Unwin, David M.; Wiemann, Jasmina; Bonadonna, Davide; Amane, Ayoub; Jakubczak, Juliana; Joger, Ulrich; Lauder, George V.; Pierce, Stephanie E. (May 7, 2020). "Tail-propelled aquatic locomotion in a theropod dinosaur". Nature. 581 (7806): 67–70.

Yao, Han; Qiu, Wenjiang; Yu, Juan; Yang, Ling; Wang, Huimin; Cao, Shenghua; Zhao, Kui; Xu, Mengyuan; Shi, Guo; Lou, Fasheng; Zeng, Cuimin; Lu, Pikun; Wu, Rui; Xu, Xing; Han, Fenglu (2026-03-30). "A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Upper Cretaceous of South China, providing further support for the possible Asian origin of Brachylophosaurini".

Mexidracon: Beast of the Week

 This week we will be taking a look at a unusual theropod.  Check out Mexidracon longimanus!

Mexidracon was a theropod dinosaur that lived in what is now Coahuila, Mexico, during the late Cretaceous period, about 72 million years ago.  From beak to tail it measured about 10 feet (3m) long.  Its genus name translates to "Mexican Dragon" and its species name to "long hand".  It may have been a plant-eater when alive or possibly eaten a mix of both plants and meat.  

Mexidracon life reconstruction in watercolor by Christopher DiPiazza.  This dinosaur may have been an omnivore, using its long hands to reach narrow places where prey might hide.

Mexidracon was a member of the ornithomimid family of dinosaurs, famous for resembling modern ostriches as a result of convergent evolution.  They had long necks with beaks with the later surviving forms lacking teeth.  The skull of Mexidracon was never found so it is difficult to know for sure if this was the case for it, but given its presence in the late Cretaceous and its close relationship to relatives we know were toothless, like Struthiomimus, it may have been as well.  Mexidracon is noted to have slightly shorter, more robust lower leg bones than other ornithomimids, but it was still likely a fast runner in life.  

Photograph of some of Mexidracon's bones with labels (in Spanish) (photo credit: Global Revista)

The most notable and unique feature about Mexidracon, however, is its hands.  The hand bones, called metacarpals (bones that make up our palms), were extremely long, which is where it earned its species name from.  It then also had three average length for an ornithomimid (but still relatively long) fingers, each tipped with a claw on each hand.  It is a total mystery why this dinosaur would evolve such an odd trait but there are a few ideas.  The first is the hands may have helped it get food, perhaps gathering vegetation or reaching into crevices or burrows of small creatures, more effectively.  The other possibility is the elongated hands may have been part of a display for members of the same species.  We know ornithomimids had feathers, so perhaps there were fancy display feathers growing there to impress mates or intimidate rivals?  We may never know.  

Mexidracon came from a habitat that paleontologists are still very much actively investigating and finding new exciting specimens from right now.  Other dinosaurs that have been found in the same area of Mexico include the hadrosaur, Velafrons, and the ceratopsian, Coahuilaceratops.

References

Serrano-Brañas, Claudia Inés; Espinosa-Chávez, Belinda; de León-Dávila, Claudio; Maccracken, S. Augusta; Barrera-Guevara, Daniela; Torres-Rodríguez, Esperanza; Prieto-Márquez, Albert (2025-01-28). "A long-handed new ornithomimid dinosaur from the Campanian (Upper Cretaceous) Cerro del Pueblo Formation, Coahuila, Mexico".