the month in snapshots

 

Dino of the Week: Saltriovenator

Type Species: Saltriovenator zanellai

Classification: Dinosauria - Saurischia – Theropoda - Ceratosauria

Time Period: Early Jurassic

Location: Italy

Diet: Carnivore

The twenty-five-foot long and one-ton Saltriovenator was the megapredator of the Early Jurassic. Its remains were discovered in modern Italy (what would’ve been southern Laurasia) in what would’ve been a watery grave. The specimen had died and been washed out to sea (or in a bay) where it was scavenged by marine organisms. At least thirty bore marks on the bones come from a variety of marine invertebrates, and its remains were entombed with a single tooth and jaw fragment from a bony fish. Saltriovenator has the unlucky distinction of being the first dinosaur discovered to have been gnawed upon by marine animals. 

The find gets even more intriguing: Saltriovenator was a large, bipedal carnivore similar to the much later Jurassic predator Ceratosaurus, and it’s classified as the oldest known ceratosaur. It was much stockier and larger than other Early Jurassic theropods, and other theropods of its size wouldn’t crop up in the fossil record until another 25 million years later. Saltriovenator’s large size took place in tandem with the emergence and gradual enlargement of sauropod herbivores, suggesting a prehistoric ‘arms race’ between predator and prey. As Dr. Simone Maganuco writes, “The evolutionary ‘arms race’ between stockier predatory and giant herbivorous dinosaurs, involving progressively larger species, [began] 200 million years ago” – more than twenty million years earlier than scientists had previously believed. 

Dino of the Week: Barapasaurus

Type Species: Barapasaurus tagorei

Classification: Dinosauria - Saurischia - Sauropoda - Gravisauria - Cetiosauridae

Time Period: Early Jurassic

Location: India

Diet: Herbivore

The Early Jurassic sauropod Barapasaurus is one of the few dinosaurs that have been discovered on the Indian subcontinent. It lived during the Sinemurian and Pliensbachian stages of the Early Jurassic (199-182 million years ago). Over 300 Barapasaurus fossils were discovered in the Godavari Valley of south central Indian in 1961. The remains included no skulls or feet, but it was determined that the remains belonged to at least six individuals. The fossils were found among large tree trunks scattered over an area of over 250 square meters. Paleontologists speculate this assemblage was due to a catastrophic flood, in which the herd of these early sauropods in a conifer forest were swept away – along with the trunks of their foodstuffs – and deposited a distance away. As they began to decompose, the bones began to disarticulate, and the disarticulated skull bones were removed by the residual water streams because they were light. 

Barapasaurus was an early sauropod, and it exemplified many of the derived sauropod traits. An adult reached about sixty-six feet from head-to-tail, and it had the elongated neck and tail of the sauropods. It had a short trunk and columnar limbs. Its vertebrae show signs of transitioning to the type seen in more derived sauropods: though Barapasaurus had rudimentary weight-saving scoops or hollows common in sauropods, they were less prevalent than those found in later sauropods. Only three whole teeth and three crowns have been discovered. The largest known tooth is 5.8 centimeters in height. Its teeth were spoon-shaped and show wrinkled enamel, as is the case with derived sauropods. Barapasaurus was likely slow and plodding, feeding for many hours a day. It stripped vegetation and swallowed its food without chewing, allowing gastroliths in the gut to break down the food for processing. 

Dino of the Week: Kotasaurus

Type Species: Kotasaurus yamanpalliensis

Classification: Dinosauria - Saurischia – Sauropoda - Gravisauria - Eusauropoda

Time Period: Early Jurassic

Location: India

Diet: Herbivore

The thirty-foot-long and 2.5-ton Kotasaurus was one of the earliest known sauropods. It shared its habitat with another sauropod, Barapasaurus. The fossilized remains of twelve individuals – lacking, unfortunately, their skulls (though two teeth have been recovered!) – were discovered in India. The remains were jumbled together in what had been a Jurassic riverbed, and scientists speculate that the herd drowned in a flash flood and was washed to a bend in the river where they were deposited en masse. Only the heaviest bones remained to be fossilized, for after the floodwaters receded, their carcasses would’ve been set upon by scavengers. The absence of skulls isn’t surprising, since skulls are very loosely connected to the spine and thus easily wrenched free and taken to other locations for eating. Kotasaurus had a heavy body, a long neck and tail, columnar limbs, spoon-shaped teeth, and a horizontal posture.  

Dino of the Week: Lufengosaurus

Type Species: Lufengosaurus young

Classification: Dinosauria - Saurischia - Prosauropoda

Time Period: Early Jurassic

Location: China

Diet: Herbivore

Lufengosaurus lived in China during the Early Jurassic around 190 million years ago. It’s similar to its contemporary Yunnanosaurus: both were prosauropods that reached to about twenty-three feet in length and half a ton in weight (though some more recent estimates have put Lufengosaurus at up to thirty feet long); both had small heads with long necks and tails, tubby torsos, and both were quadrupedal; both had deep and broad snouts; both had shorter forelimbs than hind-limbs (though Lufengosaurus’ were slightly shorter relative to the hind-limbs); and both were named only one year apart by the same paleontologist. These coincidences prompted theories that Lufengosaurus and Yunnanosaurus were the same dinosaur with intraspecies variation. This would mean that Yunnanosaurus was actually a variant species of Lufengosaurus, since Lufengosaurus was named first, in 1941. Others have built upon this theory and added a twist: both Lufengosaurus and Yunnanosaurus may have been different species of the earlier Massospondylus. Thus all three would be species of Massospondylus, and paleontological textbooks would need to be rewritten. These theories have fallen out of vogue, however, due to the fact that Lufengosaurus and Yunnanosaurus differ wildly when it comes to their teeth. Whereas Yunnanosaurus teeth were narrow and spoon-shaped (like those of sauropods), Lufengosaurus retained the widely-spaced, leaf-shaped teeth common to early sauropodomorphs. 

Lufengosaurus was herbivorous, though – like all prosauropods – it had sharp claws, especially on its thumbs, and sharp, serrated teeth. This has led some to speculate that Lufengosaurus – along with its prosauropod kin – was omnivorous. However, modern herbivorous iguanas have sharp teeth and claws, and they don’t eat meat. The strongest theory is that Lufengosaurus was herbivorous, using its sharp claws for defense or for raking foliage from trees. This prosauropod has made headlines at least twice after its discovery. First, its fossilized embryos have been discovered, and they represent the earliest evidence of vertebrate soft tissue preservation. Second, in 2017 scientists discovered 195-million-year-old collagen protein (used in connective tissues) in the fossilized rib bone of a Lufengosaurus.