Lourinhanosaurus

*Lourinhanosaurus antunesi*

***Lourinhanosaurus*** (meaning "Lourinhã lizard") was a carnivorous theropod dinosaur that lived during the Late Jurassic Period (Kimmeridgian/Tithonian) of Portugal. Its first remains were found at Peralta, near Lourinhã, Portugal in 1982, but were not described until 1998, by Portuguese paleontologist Octávio Mateus.

Its only known species is ***L. antunesi***, in honor of Portuguese paleontologist Miguel Telles Antunes.

## Material

To date, the most complete specimen of *L. antunesi* found is a partial skeleton. The holotype (ML370) is a partial skeleton, consisting of the remains of six cervical vertebrae with six ribs, five sacral vertebrae with ribs, 14 caudal vertebrae, eight chevrons, both femora, right tibia and fibula, one metatarsus, two ilia and both pubes and ischia. 32 gastroliths were also found inside the specimen. A femur (ML 555), which was found at Porto das Barcas was assigned to this genus.

A femur (ML 555) found at Porto das Barcas (Lourinhã Formation; Late Jurassic) has also been referred to *L. antunesi*.

Not far from the Lourinhanosaurus type specimen, a nest, containing around 100 eggs, some of which had fossilized embrious (ML 565) was found. These eggs are about 13 cm long.

Besides these specimens, around 100 eggs (specimen number ML 565), some of them containing embryonic bones, have been found in 1993 at the nearby beach of Paimogo These were soon assigned to *L. antunesi*.

Both the skeleton and the eggs are on display at Museu da Lourinhã.

## Classification

Relationships of *Lourinhanosaurus* have been uncertain, and no firm consensus has been reached as to its relationships. Initially regarded as a primitive member of Allosauroidea, it was later discussed as being closely related to Sinraptoridae, a more inclusive clade within Allosauroidea. Recently, some researchers have been favourable to the idea that *L. antunesi* is not even an allosauroid, But in fact, a member of the Megalosauroidea. Carrano *et al.* (2012) even found it to be a coelurosaur.

## Paleobiology

The holotype was estimated at being 4,5 metres long. However, being 4 years when it died, it was a sub-adult. The size of an adult individual was estimated at around 8 metres long, which would make Lourinhanosaurus a big theropod (for Jurassic standards), but still well inside the size range observed in other Jurassic theropods. What is most surprising, however, is the presence of Gastroliths in association with the Lourinhanosaurus remains. This wouldn't be strange if the animal in question was a herbivore. The fact that these gastroliths were found inside a carnivore made paleontologists really confused.

One possible explanation is that Lourinhanosaurus was a specialized hunter, eating , for example, shellfish and crustaceans. At the time, the sea levels were much higher and Europe was more like a giant archipelago, instead of a single big land mass. It is possible that young Lourinhanosaurus lived more in coastal ecosystems and, therefore, would have different food sources, according to their ages. This way, they would not compete with older Lourinhanosaurus and even other predators, such as Allosaurus.

When younger and smaller,‭ Lourinhanosaurus may have frequented coastal environments which were far more extensive in Jurassic Europe.‭ ‬Here they would be able to feed by either hunting smaller dinosaurs or raiding tidal pools for fish and crustaceans,‭ ‬the latter two choices requiring the use of gastroliths.‭ ‬Lourinhanosaurus that survived to adulthood may have grown too large to support themselves by this and switched to a greater reliance upon hunting other dinosaurs,‭ ‬again the two generations avoiding competition with one another for the same resources.

This strategy is also seen in Tyrannosaurs. When young, they seem to have been very fast and agile predators, making them suitable to chase down smaller and faster ornithopod dinosaurs. In later life, they grew much bigger and no longer had the agility to hunt these swifter dinosaurs which also no longer offered a sufficient return in calories,‭ ‬so the adults switched to hunting larger and heavier dinosaurs.‭ ‬This niche specialisation also allowed juveniles and adults of the same species to coexist in the same ecosystem without competing with each other for the same food.

## Appearance in other media

### *Jurassic Park*

* Several unused early designs of the logo for Jurassic Park III (then titled Jurassic Park: Extinction) feature the skeleton of a dinosaur embryo that closely resembles the fossil embryo of Lourinhanosaurus.