Level 1 — Absolute Beginner

Workers in Brazil were building a road. They dug into the ground. They dug eight metres down. Then they found big old bones.

The bones came from a dinosaur. It was very large. It was about twenty metres long. That is longer than two buses.

The dinosaur lived a very long time ago. It lived about 120 million years ago. It had a long neck and a long tail. It ate plants.

Scientists gave the dinosaur a new name. The name is Dasosaurus. It is the biggest dinosaur ever found in that part of Brazil. Scientists think more bones are still in the ground.

dig

to make a hole in the ground

bone

a hard white part inside the body of an animal

dinosaur

a very large animal that lived millions of years ago

large

big in size

ground

the surface of the earth we walk on

scientist

a person who studies nature and does experiments

name

the word we use to call a person, animal or thing

plant

a living thing like a tree, a flower or grass

Level 2 — Elementary

A new kind of dinosaur has been discovered in Brazil, and it was found by accident. Workers were building a road and rail terminal in Davinopolis, a town in the state of Maranhao. About eight metres below the surface, they uncovered large fossil bones.

At first, people thought the bones belonged to big mammals that lived at the same time as early humans. A scientist named Elver Luiz Mayer looked at them and disagreed. Because the bones lay so deep, he believed they were much older. He was right: the rock around them is about 120 million years old.

The animal has now been named Dasosaurus tocantinensis. It was a sauropod, one of the long necked plant eating dinosaurs, and it measured about twenty metres from nose to tail. Its thigh bone alone is one and a half metres long. Tail bones, ribs, foot bones and leg bones were also preserved, which makes the skeleton unusually complete.

The name has a local meaning. The first part comes from a word for forest, because the region is heavily wooded. The second part refers to the Tocantins River, which flows near the place where the fossils were found. Scientists believe more bones from the same animal are still buried at the site.

discover

to find something for the first time

by accident

not planned, happening by chance

fossil

the remains of an ancient animal or plant preserved in rock

surface

the top layer of the ground

mammal

an animal that feeds its babies with milk

sauropod

a large plant eating dinosaur with a long neck and tail

thigh bone

the large bone in the upper part of the leg

preserved

kept in good condition over a long time

Level 3 — Intermediate

A giant sauropod unearthed beneath a construction site in northeastern Brazil has been formally described in the Journal of Systematic Palaeontology under the name Dasosaurus tocantinensis. The animal stretched roughly twenty metres and lived about 120 million years ago, at the transition between the Lower and Upper Cretaceous. It is now the largest dinosaur known from the state of Maranhao, where previously described species such as the ten metre Amazonsaurus maranhensis were considerably smaller.

The circumstances of the find are typical of Brazilian palaeontology. Archaeologists monitoring a road and rail terminal at Davinopolis, as environmental licensing required them to do, recovered the bones from about eight metres down. The initial assumption was that they belonged to large Quaternary mammals. Elver Luiz Mayer, who normally studies exactly those mammals, recognised that the depth and the known age of the geological formation ruled that out, and assembled a team of specialists.

What makes the specimen valuable is not only its size but its completeness. Tail vertebrae, ribs, foot bones, limb bones and a femur one and a half metres long survived, which is a generous haul for a sauropod. Analysis of the microscopic structure of the bone, led by Tito Aureliano and Aline Ghilardi, revealed a growth pattern mixing features of earlier sauropods with those of titanosaurs. That suggests certain strategies for growing and remodelling bone appeared earlier in the group's history than had been assumed, which may help explain how these animals reached such sizes.

The biogeography is the most striking result. The closest known relative of Dasosaurus lived in what is now Spain. The researchers propose that its ancestors reached South America by way of North Africa between 140 and 120 million years ago, while those landmasses were still connected within the supercontinent Gondwana. The discovery also illustrates a tension familiar to the field: major construction projects destroy fossil beds, but they also expose rock that no research budget would otherwise reach.

unearth

to dig something up out of the ground

formally described

officially published as a new species in a scientific journal

vertebra

one of the small bones forming the backbone (plural: vertebrae)

femur

the thigh bone, the long bone of the upper leg

remodelling

the process by which bone is broken down and rebuilt

biogeography

the study of where living things are found and why

supercontinent

a very large landmass made of several present day continents joined together

tension

a conflict between two things that pull in opposite directions

Level 4 — Advanced

Dasosaurus tocantinensis, described this month in the Journal of Systematic Palaeontology, is a titanosauriform of roughly twenty metres recovered from sediments at the Lower to Upper Cretaceous transition, some 120 million years old. It is the largest dinosaur yet known from Maranhao, a state whose previous sauropod record consisted of the comparatively modest ten metre diplodocid Amazonsaurus maranhensis, and it was found not by survey but by excavation for a road and rail terminal at Davinopolis.

The recovery narrative is instructive about how vertebrate palaeontology actually proceeds in a densely vegetated tropical country. The bones surfaced under environmental licensing monitoring and were initially attributed to large Quaternary mammals, an entirely reasonable first reading given the region's fauna. It was the stratigraphic position, roughly eight metres down in a formation whose age was already established, that made the attribution untenable. Elver Luiz Mayer, a specialist in precisely the mammals the bones were mistaken for, drew that inference and convened a multidisciplinary team rather than pursuing it alone.

Two results carry beyond the description of a new taxon. The first is histological: analysis of bone microstructure by Tito Aureliano and Aline Ghilardi found a growth and remodelling signature combining traits of earlier sauropods with those characteristic of titanosaurs, implying that some of the tissue level strategies underpinning gigantism were established earlier in somphospondylan history than the prevailing reconstruction allowed. The second is biogeographic: the taxon's closest known affinities lie with an Iberian form, and the authors infer dispersal into South America through North Africa between 140 and 120 million years ago, across connections still available within Gondwana. A single well preserved specimen thus constrains both a developmental question and a continental one.

The episode also restates an unresolved structural problem. Infrastructure work is simultaneously the principal destroyer of Brazilian fossil localities and, in terrain where outcrop is scarce and vegetation total, the principal means of exposing them; map the country's fossil sites and you substantially map its highways and quarries. The protective apparatus exists in federal law, but specialist monitoring and recovery are applied unevenly, and here they functioned largely because a qualified observer happened to look twice at a misidentified box of bones. The team is now negotiating with the construction company for access to continue excavating, on the reasonable expectation that more of the animal remains in the ground.

taxon

a named group of organisms, such as a species (plural: taxa)

sediment

material that settles in layers and hardens into rock

stratigraphic

relating to the layers of rock and their order

untenable

impossible to defend or maintain