Level 1 — Absolute Beginner

Workers in Brazil were building a new road and railway. They dug deep into the ground.

Under the ground they found big old bones. The bones were from a dinosaur.

The dinosaur was very long. It was about twenty meters, longer than two buses. It had a long neck and ate plants.

Scientists gave the animal a new name. It lived 120 million years ago. They think more bones are still under the ground.

worker

A person who does a job.

ground

The land under your feet.

bone

A hard white part inside the body.

dinosaur

A very large animal that lived long, long ago.

long

Measuring a lot from one end to the other.

neck

The part of the body between the head and the shoulders.

plant

A living thing that grows in the ground, like grass or a tree.

name

The word we use to call a person or thing.

Level 2 — Elementary

A construction crew in northeastern Brazil was digging the foundations of a road and rail terminal at Davinopolis, in the state of Maranhao, when it hit fossil bone about eight meters below the surface.

Palaeontologists have now described the animal and given it a name: Dasosaurus tocantinensis. It was a sauropod, one of the long necked plant eating giants, and it measured roughly twenty meters from nose to tail. It lived about 120 million years ago, in the Early Cretaceous period.

The surprise was not the size but the family tree. When the researchers compared the bones with other sauropods, the closest match was a species from Spain, thousands of kilometers away across an ocean that did not yet exist in its modern form.

The team believes the ancestors of the Brazilian animal spread into South America through North Africa somewhere between 140 and 120 million years ago, while the continents were still linked as part of Gondwana. The findings appear in the Journal of Systematic Palaeontology, and the researchers suspect that more of the skeleton is still buried at the site.

construction

The work of building roads, houses or other structures.

foundation

The solid base built under a structure.

fossil

The preserved remains of an animal or plant from long ago.

palaeontologist

A scientist who studies fossils.

sauropod

A group of very large dinosaurs with long necks and tails that ate plants.

species

A particular kind of living thing.

ancestor

A relative who lived a very long time before you.

continent

One of the world's very large land masses.

Level 3 — Intermediate

Most new dinosaurs are found by people looking for dinosaurs. This one was found by a crew laying the foundations of a road and rail terminal at Davinopolis, in the northeastern Brazilian state of Maranhao, who struck fossil bone roughly eight meters below the surface and stopped digging.

The animal has now been formally described as Dasosaurus tocantinensis in the Journal of Systematic Palaeontology. It was a sauropod, the lineage of long necked herbivores that includes the largest land animals ever to have lived, and it reached about twenty meters in length. The rocks place it in the Early Cretaceous, roughly 120 million years ago.

The interesting result is not the measurement but the phylogeny. When the team ran the anatomy through a comparative analysis, the closest relative it recovered was a species from Spain rather than any of the sauropods already known from South America. That is the kind of result which, in an earlier era of the science, would have been treated as an error.

It is instead a consequence of geography that no longer exists. The researchers argue that the lineage dispersed into South America by way of North Africa between roughly 140 and 120 million years ago, while Gondwana still connected the southern landmasses and the Atlantic was a narrowing gap rather than an ocean. Excavation at the terminal site continues, and the team suspects a substantial part of the skeleton remains in the ground.

lineage

A line of descent from an ancestor through time.

herbivore

An animal that eats only plants.

phylogeny

The evolutionary history and family relationships of a group of organisms.

anatomy

The physical structure of a body.

comparative

Based on comparing two or more things.

disperse

To spread out over a wide area.

landmass

A large continuous area of land.

excavation

The careful digging out of buried material.

Level 4 — Advanced

The circumstances of discovery are worth dwelling on, because they are becoming typical. Dasosaurus tocantinensis was not prospected for. It emerged from the foundation works of a road and rail terminal at Davinopolis in Maranhao, northeastern Brazil, when excavation some eight meters down encountered bone that was plainly not modern. Infrastructure projects now uncover a meaningful share of new vertebrate taxa, an accidental partnership between development and palaeontology that is as fragile as it is productive, since a crew under schedule pressure has every incentive not to notice what it has hit.

Formally described in the Journal of Systematic Palaeontology, the animal was a sauropod of approximately twenty meters, recovered from Early Cretaceous strata deposited around 120 million years ago. The dimensions are respectable without being exceptional for the clade, and on their own would justify a modest paper. What elevates the find is the position the specimen occupies once its anatomy is entered into a comparative phylogenetic analysis.

The nearest relative the analysis recovers is not South American at all but Iberian. That result would have been dismissed as contamination or misidentification within living memory, and it is now merely surprising, because the plate tectonic framework that makes sense of it is thoroughly established. The authors propose a dispersal from Europe through North Africa and onward into South America somewhere between 140 and 120 million years ago, during the interval in which Gondwana had begun to fragment but had not yet finished, and in which the proto Atlantic remained narrow enough to be crossed by land connections that flickered in and out of existence with sea level.

The wider significance lies in what the specimen implies about sampling. If a single terminal excavation in Maranhao can produce a twenty meter sauropod whose closest known relative sits on another continent, the apparent provinciality of Cretaceous South American faunas may be partly an artefact of where palaeontologists have historically been able to dig. The team reports that a substantial portion of the skeleton is likely to remain in situ, and that the surrounding sediments may hold more. Whether they are recovered will depend, as it usually does, on whether the excavation timetable can be persuaded to wait.

prospect

To search an area systematically for something valuable, such as fossils or minerals.

taxon

A named group in biological classification, such as a species or genus.

strata

Layers of rock laid down over time.

clade

A group of organisms sharing a single common ancestor.

tectonic

Relating to the movement of the large plates that make up the Earth's crust.

dispersal

The spread of a group of organisms into new areas.

in situ