User:John Troodon/Science 1

A NEW NODOSAURID(ORNITHISCHIA, THYREOPHORA) FROM LATE CRETACEOUS OF TEGANA FORMATION, MOROCCO

Abstract

New yet unnamed genus of Nodosauridae from Tegana Formation (Lavocat 1954; Monbaron 1978 ), Morocco, is described and classified. Aspects of this animal’s anatomy are described in detail; much attention is paid to its armour , teeth and lifestyle. Key words: Nodosaurid, Morocco, Tegana Formation, Cenomanian, Late Cretaceous.

Introduction

Tegana Formation is mostly known for its dinosaur fossils: Carcharodontosaurus saharicus, Spinosaurus aegyptiacus and S.moroccanus, Rebbachisaurus garasbae are common examples. However there wasn’t found any Ornithischian or Ankylosaur. But new discovery revealed that they lived there.

General description

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In 2010, in Tegana Formation, in Morocco., was found a piece of sandstone with dinosaur and other animal fossils.There were:

A tooth of Carcharodontosaurus saharicus(Stromer, 1931);
A fish dorsal vertebra;
A half of Dromaeosauridae “killing toe claw”;
An unidentified animal vertebra;
A tooth of sauropod, possibly Rebbachisaurus garasbae(Lavocat, 1954);
A set of dinosaur bones.

This bones were unearthed from this monolith in March 2011, and analyzed in June. Among these unidentified remains, was a piece of osteoderm(see Figure 1). This osteoderm is very similar in shape to an osteoderm of Nodosaurus(Marsh, 1889) , member of Nodosauridae. It was 0.7 cm long. Also there was found a rib, a piece of anterior tooth(Figure 2), and a skull cap .

The strangest thing about the tooth is that it is not serrated. Most ankylosaur teeth have large serrations up to 0.2 mm. The tooth of “African nodosaurid” has no serrations at all. However fossils are too small. Perhaps they belong to juvenile. So, unfortunately, adult specimen is unknown, as in Liaoningosaurus(Xu, Wang & You, 2001). Its rib was relatively short and not very recurved, as in other nodosaurs, like Gastonia(Kirkland, 1998). In fact, this African nodosaur is remarkably similar to Minmi(Molnar, 1980), a genus of Nodosauridae from Australia. Tegana Formation formed circa 95 million years ago, in late Cenomanian, so it also lived at the same time as Minmi. Dorsal vertebrae are also very short, and therefore fused. They were very thin and because of this, nodules were hollow, to help the animal to bear its weight Brain Brain cavity of this ankylosaur is relatively large, compared to his relatives. It left imprints in the skull cap. Howewer this feature could be present only in juveniles. In Troodon (Leidy, 1856), for instance, eyes were huge in babies, and a little smaller in adults. Juveniles need acute senses and big eyes to quickly spot a predator. Adults, on the other hand, are larger, and in less fear of attack.

Growth and Lifestyle

This unique juvenile specimen coud shed light on growth of thyreophoran dinosaurs .

Hatchling and size

As I said it is the second juvenile ankylosaur ever found. Among his bones was also a small(0.2 mm) piece of eggshell. This means that this particular specimen was a hatchling. So adult of this species would be approximately 6 metres(20ft) long. This hatchling had very weak and big teeth. Perhaps he didn’t feed by himself. His parents brought food to the nest, and fed him. The same sort of “maternal instinct” is seen in hadrosaurs, such as Maiasaura(Horner & Makela, 1979).

Nodules

Another interesting feature of this specimen is that its nodules were relatively large, and therefore hollow and pitched It didn’t have reinforced ridge on top of the plate. This means that this specimen is actyally more primitive animal, than Nodosaurus and its relatives.

References

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Random House

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