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Ankylosauria (“Fused Lizard”)

These heavily armoured dinosaurs were equipped with bony plates, studs, spikes, and in one lineage (Ankylosauridae) a bony tail-club. Where does the name "fused lizard" come from? Ankylosaur characteristics evident in their skeleton: • low skull with added dermal bone and closure of fenestrae. • • rings of osteoderms over the neck and shoulders • modifications of rib cage and hip girdle • stocky, quadrupedal • small, leaf-shaped teeth • spikes and/or tail club • hind-limb lengths exceeding forelimb lengths by 50%, probably making them • body was round and broad There are two main families, the Ankylosauridae and the Nodosauridae based on armor and skeletal supports. Ankylosauridae members include Ankylosaurus, Euplocephalus, Sarcolestes, Pinacosaurus, Talarurus, Shamosaurus, Amtosaurus, Saichania, Sauroplites, and Tarchia. Nodosauridae possess at least 9 shared characteristics, one of which includes parascapular spines as well as numerous spines along their sides, or on top of their necks. Nodosauridae members include Acanthopholis, Hylaeosaurus, Panoplosaurus, Sauropelta, Polacanthus, Minmi, Edmontonia, Nodosaurus, Pawpawsaurus, and Silvisaurus. They were never very common in terms of individuals, although a large number of different species are known, mainly from fragmentary remains. We do not know much about the pattern of armour and spines along the neck, back and tail except in 3 of 4 species. The two best known are A common characteristic of all dinosaurs within ankylosauria was

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In Ankylosaurids In Nodosaurids the skull is as broad as it is wide, with S-shaped nasal passages

the skull is narrow and long, as in the stegosaurs, with straight nasal passages

scutes are asymmetrically arranged,

scutes are symmetrically arranged

primitive ankylosaurs have 5 toes on the forefeet and advanced ones have 4 toes, the hind-feet typically have 3 toes in ankylosaurids

primitive ankylosaurs have 5 toes on the forefeet and advanced ones have 4 toes, the hind-feet typically have 4 toes in nodosaurids

presence of a tail club

absence of a tail club

Shared characteristics of Ankylosaurs: • stocky quadrupedal animals • low, broad heads with simple, leaf-shaped teeth that indicate they were herbivores • body was round and broad and probably housed a large gut • they had short limbs with hind-limb lengths exceeding forelimb lengths by 50%,

probably making them rather slow and graviportal • The toes ended in broad hooves (semiplantigrade) probably cushioned by pads of

cartilage What does the ankylosaur skull look like? Representative Members of Ankylosauridae What does the name Nodosaurus mean and who named it? Nodosaurus was a large, armored, quadrupedal dinosaur. It lived during the Early Cretaceous Period, about 113-98 million years ago and was about 4-6 m long. What does Sauropelta mean?

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Sauropelta was an armored nodosaur from the Early Cretaceous Period (116-91 ma). It was about 7 m long and weighed over 3 tonnes. It had a narrow skull with massive jaws, small, leaf-shaped cheek teeth and a toothless horny beak. It had horn-covered plates embedded in its skin all over its body (except on its underbelly). It lacked bony nodes at the end of its tail or horns on its head. Fossils were found in Montana, some of them nearly complete. Sauropelta was discovered and named by John Ostrom and Grant Meyer in 1970. Ankylosaurus means It was a huge armored dinosaur, measuring about 7.5-10.7 m long, 1.8 m wide and 1.2 m tall; it weighed roughly 4 tonnes. Ankylosaurus was the last of the ankylosaurids to evolve, and the biggest. It lived in the Late Cretaceous Period (70-65 million years ago). How was it protected from carnivores like Tyrannosaurus, Tarbosaurus, and Deinonychus? Ankylosaur Paleobiology and Paleoecology Ankylosaurs existed from Middle Jurassic to Late Cretaceous (~175 - 65 million years). Maximum diversity: at least 9 genera being known from the Late Cretaceous. There are at least 20 genera known (with 25 species) throughout their time on Earth. 6 or 7 genera are known only from fragmentary skeletal remains. The group has been found in Skeletal Conditions Ankylosaur skeletons from Asia Those from North America are only partial skeletons and are commonly preserved upside down. They are also commonly preserved in coastal margin or marine sedimentary beds, suggesting

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Behaviour Ankylosaur social behaviour mostly is mostly unknown. Most do not believe that they traveled in herds and may have been largely solitary. For the most part only individual skeletons or isolated remains have been found. Locomotion Ankylosaur trackways were found in 1996 near Sucre, Bolivia, South America showing that these quadrupedal animals could run at a "decent jog," according to Swiss paleontologist Christian Meyer. Eating Ankylosaurs were low-browsers (feeding less than 1 m above ground level). Ankylosaurs have a mix of characteristics, some of which suggest sophisticated oral food processing and others of which suggest simple oral food processing combined with internal food breakup. Sophisticated Oral Food Processing: Simple Oral Food Processing Combined with Internal Food Breakup: Teeth are relatively small, simple, loosely spaced, and leaf-shaped (triangular). All taxa had very few teeth in either jaw that did little grinding and lack well-developed wear surfaces on the crowns. They appear to have been mainly for slicing. Ankylosaurs probably all had gizzards with stones to assist in mechanical breakdown of plant material, though gastroliths have only been found in a few specimens. Their huge abdominal cavity, defined by the very deep rib cage may have housed huge bacterial fermentation chambers.

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Why do scientists think they were selsctive feeders? Asian ankylosaurs are most commonly found in arid or semi-arid depositional environments, and therefore must have been consumed plants adapted to water stress. North American ankylosaurs are found in coastal settings where vegetation would have been lush and lacked such protective structures. Some ankylosaurs have been found in relatively arid settings at Devil’s Coulee, Alberta. It is possible that many of the ankylosaurs that have been found in coastal settings have been transported there after death, and the group may have preferred semi-arid or arid settings. Brains Ankylosaurs had small brains and large olfactory bulbs that suggest a good sense of smell. Advanced ankylosaurids also had curved thin bones within their nasal passages Defense Ankylosaurs probably used a combination of employing defensive weapons and a tortoise-like strategy of hunkering down and letting the armour do its job. The shoulder region, particularly in the Nodosaurids, was heavily muscled allowing them to employ their parascapular spines effectively. It is almost certain that it must have served at least partly as an “antipredator device”. They likely planted their rear legs firmly and rotated their forequarters to present their spines toward the predator.

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Ankylosaurids lacked the parascapular spines but had a massive tail club. The front half of tail was highly flexible, but the rear half was stiffened by modified vertebrae and longitudinally running tendons. These tendons also provided the attachment of powerful muscles. The tail club could have been forcefully swung side to side, making it a potent threat to the legs of any theropod. Display and Intimidation Sexual display is used to attract a potential mate. What is agonistic display? Agonistic display can be divided into threat and intimidation. Threat behaviour involves the prominent display of a weapon toward the opponent and signals a willingness to fight. Intimidation is In the nodosaurid Edmontonia, the shoulder spine is bifurcated and suggests In both the ankylosaurs and nodosaurs, it is possible that they could have “blushed” so that the armour had a pink tint as a result of the infusion of blood under the horny covering of the armour. The vascular grooves covering the surface of most of the armor indicate that a rich supply of blood was present. In this way, they have been similar to the Stegosaurs. Displays may have been for intimidation or for sexual display.