My Dinos&Others

Some taxa I named:


  1. Lourinhanosaurus antunesi n. gen. et sp. (1998), theropod dinosaur from Portugal 

  2. Dinheirosaurus lourinhanensis n. gen. et sp. (1999), sauropod dinosaur from Portugal

  3. Tangvayosaurus hoffeti n. gen. et sp. (1999), sauropod dinosaur from Laos 

  4. Draconyx loureiroi n. gen. et sp. (2001), ornithopod dinosaur from Portugal

  5. Lusotitan n, gen. (2003), sauropod dinosaur from Portugal

  6. Europasaurus holgeri n. gen. et sp. (2006), sauropod dinosaur from Germany

  7. Allosaurus europaeus n. sp.  (2006), theropod dinosaur from Portugal

  8. Diceratus n. gen. due to preoccupied name (2008), ceratopsian dinosaur from USA

  9. Microceratus n. gen. due to preoccupied name (2008), ceratopsian dinosaur from Asia

  10. Prognathodon kianda n. sp. (2008), mosasaur from Angola

  11. Miragaia longicollum n. gen. et sp. (2009), stegosaurian dinosaur from Portugal

  12. Dacentrurinae n. clade (2009), stegosaurian dinosaurs

  13. Angolachelys mbaxi n. gen. et sp. (2010), chelonian from Angola

  14. Angolachelonia n. clade (2010), eucryptodiran chelonians

  15. Angolatitan adamastor n. gen. et sp. (2011), sauropod dinosaur from Angola

  16. Lusonectes sauvagei n. gen et sp. (2012) plesiosaur from Portugal

  17. Kaatedocus siberi n. gen et sp. (2013), sauropod dinosaur from USA

  18. Choneziphius leidyi n. sp. (2013) ziphiid whale from Iberia

  19. Globicetus hiberus n. gen et sp. (2013) ziphiid whale from Iberia

  20. Tusciziphius atlanticus n. sp. (2013) ziphiid whale from Iberia

  21. Imocetus piscatus n. gen et sp. (2013) ziphiid whale from Iberia


Miragaia longicollum

 Miragaia longicollum is the new stegosaur dinosaur found in Portugal.


A new plated dinosaur surprised Portuguese scientist by its very long neck. Stegosaurian dinosaurs are known for the short forelimbs, short necks, and are generally considered to be low browsers. However, this new Portuguese dinosaur has a higher neck vertebrae count than most of the iconically long-necked sauropod dinosaurs, which contrasts with related species like Stegosaurs. 
This raised a discussion on the neck evolution in dinosaurs when compared with giraffes, and whether that evolved by sexual selection or by niche partitioning. 

This new Jurassic species with 150 million years was named Miragaia longicollum, meaning long-necked beautiful Gaia (Godess of the Earth) and uncovered in a village with the same name, Miragaia, near Lourinha, in Portugal. 

This finding is based upon a partial articulated skeleton, and includes the only known cranial remains from any European stegosaur.


Taxonomy: Dinosauria: Stegosauria: Dacentrurinae

Locality: Migaraia, Lourinhã, Portugal

Age: 150 million years, Late Jurassic

EtymologyMiragaia, after the locality and geological unit of the same name; longicollum, after the Latin longus (long) and collum (neck), in reference to its long neck. In addition, the stem Mira- can be read as the feminine form of Latin mirus, meaning wonderful, while Gaia is the Greek goddess of the Earth, so the name also means ‘wonderful goddess of the Earth’

Authors: Octávio Mateus, Susannah Maidment, Nicolai Christiansen.

Housed in the Museum of Lourinhã, in Portugal





  


Mateus, O, Maidment, S. & Christiansen, N. 2009. A new long-necked 'sauropod-mimic' stegosaur and the evolution of the plated dinosaurs. Proceedings of the Royal Society B

(see PDF below)


Abstract: Stegosaurian dinosaurs have a quadrupedal stance, short forelimbs, short necks, and are generally considered to be low browsers. A new stegosaur, Miragaia longicollum gen. et sp. nov., from the Late Jurassic of Portugal, has a neck comprising at least 17 cervical vertebrae. This is eight additional cervical vertebrae compared to the ancestral condition seen in basal ornithischians such asScutellosaurus. Miragaia has a higher cervical count than most of the iconically long-necked sauropod dinosaurs. Long neck length has been achieved by ‘cervicalisation’ of anterior dorsal vertebrae and probable lengthening of centra. All these anatomical features are evolutionarily convergent with those exhibited in the necks of sauropod dinosaurs. Miragaia longicollum is based upon a partial articulated skeleton, and includes the only known cranial remains from any European stegosaur. A well-resolved phylogeny supports a new clade which unites Miragaia and Dacentrurus as the sister group toStegosaurus; this new topology challenges the common view of Dacentrurus as a basal stegosaur.

FAQ

1. Please describe how M. longilicollum looked and might have behaved, based on its skeletal remains.

Miragaia longicollum and other stegosaurs were quadrupedal plant-eater dinosaurs with a row of plates and spines along the body, from the neck to the tail. Swinging the two pairs of long tail spines granted them an effective defence. The full body length was about 6 meters long and about 2.5 m high. The small head had tiny teeth adapted to cut vegetation. Contrary to other stegosaur dinosaurs, Miragaia longicollum had a long neck with 17 vertebrae, which is as much as long-necked sauropod dinosaurs.

We know little about the behaviour: we are yet to discover if they lived in groups or alone, how they nest and reproduce, and even how their physiology was.

 

2. Some paleontologists argue that dinosaurs held their necks in a more horizontal position, parallel to the substrate. Could that have been the case for your new dinosaur, or does the anatomy suggest that the head and neck were indeed held up in the air, similar to a giraffe today?

 The anatomy of the vertebrae suggests that the neck was at shoulder level, horizontally parallel to the ground. They could raise the neck and head but that was not the body neutral position.


3. Thinking of giraffes, was there any link between this modern animal and the long-necked dinosaurs, or is the neck similarity simply a case of independent invention/evolution of a somehow useful or desirable trait?

 There is no direct lineage between this dinosaur and the giraffes or any other mammal, therefore the long neck evolved independently as in many other animals through different evolutionary strategies: Miragaia longicollum, plesiosaurs, swans, sauropods have many neck bones, while giraffes has only seven, but very long, vertebrae. 

On other hand, the evolutionary reason may be the same: niche partitioning and sexual selection.

 

4. Using simple terms, please describe what "cervicalization of dorsal vertebrae" is and what might have driven that process in the dinosaur.

 

Cervicalization of dorsal vertebrae consists in the evolutionary transformation of dorsal (back) in cervical (neck) vertebrae, making a longer neck and the body trunk shorter, driven by the evolutionary advantage, either by niche portioning or sexual selection.

 

5. It sounds like you have your doubts that niche partitioning prompted the evolution of the dinosaur's long neck. Why might possessing a long neck have arose due to sexual selection? Isn't that normally tied to fitness? I was a bit surprised by Senter's proposed six characters, since the two mentioned in your paper weren't linked to fitness. And do you think both males and females of this species had long necks?

Even for the modern well-studied giraffes there are dubious results: some studies suggest they evolved a long neck through sexual selection, while others suggest that niche partitioning was the main evolutionary mechanism. In a 150 million years fossil is even harder. Secondary sexual characters are often exaggerated body or behavioural features that reduce hypotheses of survival but enhance chances of sexual selection, like intense colours, long tails, exaggerated antlers, and possibly, long necks.

We did not mention fitness because that is very difficult to determine in the fossils. We need more specimens in order to determine if there was sexual dimorphism in the neck size of Miragaia longicollum.

 


6. Your paper mentions that a juvenile dinosaur was found next to the primary remains described in your paper. Is it likely that this other dinosaur also represents M. longicollum? If not, what species might it have been?

The other specimen found in the fossil site together with Miragaia longicollum is also a stegosaur. We believe that might be the same species but new findings and better anatomy studies are required to prove it.


7. If possible, please e-mail any additional accompanying images and multimedia, aside from the one good illustration provided with the press materials.