DinoFiles

i have always been fascinated by prehistoric life and in my spare time i love to study and research dinosaurs.

dinofiles is the place on the internet where i come share my findings and knowledge for others to hopefully enjoy and learn from.

Placodonts:
                The placodonts were a strange group of marine reptiles that appeared during the mid-Triassic period but became extinct at the Triassic/Jurassic boundary. They were heavy-bodied swimmers that mostly fed on shellfish; their teeth were specialised for picking shells from rocks and crushing them between their jaws. It is believed that placodonts were not confined to water, and would have been able to travel on land.

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Name: Cyamodus
Pronounced: Sigh-Ah-Mode-Uss
Classification: Placodontia
Sub-family: Cyamodontid
Temporal Range: Middle Triassic (245-228 Mya)
Length: 1.3 metres

Information:
- Discovery:Cyamodus  was discovered in Germany, and was officially named in 1863 by palaeontologist Christian Erich Hermann von Meyer. Cyamodus is a member of the placodont family, and more specifically belongs to the placodont sub-family; cyamodontid.

- Description: Cyamodus measured around 1.3 metres in length and its most characteristic feature is the two-part shell or carapace found on the upper surface of the body. The main part of the shell covers the body to the hips and spreads out sideways, almost covering the animals forelimb span. The second part of the shell is smaller in size and covers the animals hips and the base of the tail. Both shell parts are covered in hexagonal and circular plates of armour. The skull is heart-shaped, and is particularly strong at the rear.

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Name: Henodus
Pronounced: Hen-Oh-Duss
Classification: Placodontia
Sub-family: Cyamodontid
Temporal Range: Late Triassic (228-220 Mya)
Length: 1 metre

Information:
- Discovery:Henodus  was also discovered in Germany, although it was found later than the fossils of Cyamodus, and was officially named in 1936. Like Cyamodus, Henodus is a member cyamodontid family of placodonts.

- Description: Henodus is the placodont which most closely resembles a turtle. There is a carapace covering the whole body which stretches out well beyond the span of the limbs. It is believed Henodus would have acted as some kind of reptilian ray; paddling its broad, flat body along the bed of shallow lagoons, foraging in the sand with its broad mouth. The weak limbs of Henodus suggest that this placodont would not have spent much time on land, and the fact that it is the only placodont not to be found in marine sediment suggests that it lived in brackish or freshwater lagoons. 



Picture Source: Kahless28 (deviant art)

           The Triassic is a period of time which extends from 251 to 199.6 Mya (million years ago). The name Triassic was coined by German geologist Friedrich Von Alberti in 1834, and relates to the three distinct rock layers that formed during the era. These rock layers can be seen throughout Germany and northwestern Europe and are formed of a layer of red beds, capped by a layer of chalk, followed by black shales. Fauna:             The Triassic follows a period of time known as the Permian, and began in the wake of the Permian-Triassic extinction event; an event which left the Earth’s biosphere impoverished. Terrestrial life did not fully recover and diversify until midway through the Triassic era. The shelled, marine-dwelling, ammonites recovered, expanding from a single line which survived the Permian extinction. The fish fauna for the period remained very uniform, highlighting the fact that very few fish families survived through to the Triassic. Despite this, there were a large number of marine reptiles present throughout the Triassic. These included pachypleurosaurs, nothosaurus, placodonts, the first plesiosaurs and the highly successful ichthyosaurs.             On land, the early Triassic period was dominated by basal amphibians and a handful of therapsids (the ancestors of mammals), which had managed to survive the extinction event. However as the Triassic period progressed the therapsids were slowly displaced by archosaur reptiles (the ancestors of dinosaurs). The increase in archosaur numbers likely forced the surviving therapsids and their mammalian succesors to live as small, mainly nocturnal insectivores. The archosaurs on the other hand, evolved at a rapid pace, with different clades of archosaur evolving into different things.  By the mid-Triassic the first pterosaurs and dinosaurs were present; but shared land space with a number of other reptile groups, including the aetosaurs, the rhynchosaurs, the first turtles, and the first crocodilians (the sphenosuchians). Geography & Climate:            During the Triassic, almost all the Earth’s land mass was concentrated into a single supercontinent, known as Pangea. The mid-Traissic saw Pangea begin to gradually rift into two separate landmassed, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea’s interior. However, the climate shifted and became more humid as Pangaea began to drift apart. There is no evidence of glaciation at or near either pole; in fact, the polar regions were apparently moist and temperate, a climate suitable for reptile-like creatures.  This following few weeks will be dedicated to all things Triassic! To begin with we will look at all the non-dinosaur animals which lived during the Triassic period, and eventually build this up into some detailed Triassic dinosaur fact-files. So if there is a Triassic dinosaur you want a fact-file about, please, please, please let me know!

           The Triassic is a period of time which extends from 251 to 199.6 Mya (million years ago). The name Triassic was coined by German geologist Friedrich Von Alberti in 1834, and relates to the three distinct rock layers that formed during the era. These rock layers can be seen throughout Germany and northwestern Europe and are formed of a layer of red beds, capped by a layer of chalk, followed by black shales.

Fauna:
            The Triassic follows a period of time known as the Permian, and began in the wake of the Permian-Triassic extinction event; an event which left the Earth’s biosphere impoverished. Terrestrial life did not fully recover and diversify until midway through the Triassic era. The shelled, marine-dwelling, ammonites recovered, expanding from a single line which survived the Permian extinction. The fish fauna for the period remained very uniform, highlighting the fact that very few fish families survived through to the Triassic. Despite this, there were a large number of marine reptiles present throughout the Triassic. These included pachypleurosaurs, nothosaurus, placodonts, the first plesiosaurs and the highly successful ichthyosaurs.
            On land, the early Triassic period was dominated by basal amphibians and a handful of therapsids (the ancestors of mammals), which had managed to survive the extinction event. However as the Triassic period progressed the therapsids were slowly displaced by archosaur reptiles (the ancestors of dinosaurs). The increase in archosaur numbers likely forced the surviving therapsids and their mammalian succesors to live as small, mainly nocturnal insectivores. The archosaurs on the other hand, evolved at a rapid pace, with different clades of archosaur evolving into different things.  By the mid-Triassic the first pterosaurs and dinosaurs were present; but shared land space with a number of other reptile groups, including the aetosaurs, the rhynchosaurs, the first turtles, and the first crocodilians (the sphenosuchians).

Geography & Climate:
            During the Triassic, almost all the Earth’s land mass was concentrated into a single supercontinent, known as Pangea. The mid-Traissic saw Pangea begin to gradually rift into two separate landmassed, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea’s interior. However, the climate shifted and became more humid as Pangaea began to drift apart. There is no evidence of glaciation at or near either pole; in fact, the polar regions were apparently moist and temperate, a climate suitable for reptile-like creatures. 

This following few weeks will be dedicated to all things Triassic! To begin with we will look at all the non-dinosaur animals which lived during the Triassic period, and eventually build this up into some detailed Triassic dinosaur fact-files. So if there is a Triassic dinosaur you want a fact-file about, please, please, please let me know!

Since I haven’t got the time to write up a full dinosaur fact file tonight, I thought I’d tell you about a piece of literature that you must, must own if you enjoy prehistoric life. 

The Complete Book of Dinosaurs by Dougal Dixon

This book is truly fascinating. The front cover description reads as follows; ‘The ultimate reference to 355 dinosaurs from the Triassic, Jurassic and Cretaceous periods, including more than 900 illustrations, maps, timelines and photographs’.

Personally, I think the wealth of detailed illustration is what makes this book ideal for anyone; from casual dinosaur fan, to professional palaeontologist. Don’t get me wrong, the fact-files are informative and there is plenty to be learnt through reading; but the true enjoyment of owning this book comes through flicking through the immensely colourful artwork. 
In addition, the book is 255 pages long, although the first 65 pages are dedicated to topics that many amateur palaeontology enthusiasts often overlook.  From dinosaur habitats to details on the worlds most famous palaeontologists; from the dinosaur classification system to an explanation of how fossilisation actually occurs. Dougal Dixon has produce a book where there is something enjoyable for everyone; and one where everyone will learn something enjoyable.

 
Check link above for where to buy ‘The Complete Book of Dinosaurs’ from amazon.co.uk  

Name: Adasaurus
Pronounced: Ah-Dah-Saw-Russ
Classification: Theropod
Sub-family: Dromaeosaurid
Temporal Range: Late Cretaceous (75-65 Mya)
Length: 1.8 metres
Height: 0.7 metres
Weight: unknown
Movement: Bipedal
Feeding Type: Carnivore

Information:
- Discovery: Adasaurus is the genus of a fairly small, dromaeosaurid dinosaur from the Late Cretaceous period. Two specimens have been discovered, both from the Nemegt Formation in Mongolia. The first specimen consists of a partial skull, an almost complete vertebral column (just the end of the tail is missing), pelvic bones, the shoulder girdle and bones from the hindlimbs. The second individual is more incomplete, and consists almost entirely of only fossils from the back end of an animal. Adasaurus was first named and described in 1983, by the famous Mongolian palaeontologist Rinchen Barsbold.
            The positioning of Adasaurus within the dromaeosaurid family is one of much uncertainty. Relationships within the dromaeosaurid group are fairly poorly understood as it is; however it would appear that Adasaurus is a member of the dromaeosaurine sub-family, along with the Mongolian Achillobator.

- Statistics: Adasaurus was fairly small, even for a dromaeosaurid. Researchers believe that an adult would have reached a maximum of around 1.8 metres in total body length; and the lack of fossil discoveries have made weight estimates difficult to ascertain.

- Description: Adasaurus is one of the more obscure dromaeosaurids to be unearthed in central Asia. However, one of the most striking characteristics established from study of its limited fossil remains, is that the sickle-shaped claw, found on the second toe of each hind foot, was much smaller than those seen in over dromaeosaurids. These shorter claws have led researchers to suggest that Adasaurus would have preyed on the smaller animals found throughout Cretaceous Asia. Like most dromaeosaurids, it is hypothesised that Adasaurus would have sported a feathery coating.


Top Picture Source: Eduardo Camarga (taken from about.com)
Bottom Picture Source: Unknown (taken from theropoda.blogspot) 

Name: Acrocanthosaurus
Pronounced: Ah-Crow-Can-Fo-Saw-Russ
Classification: Theropod
Sub-family: Carcharodontosaurid
Temporal Range: Early Cretaceous (116-110 Mya)
Length: 11.5 metres
Height: 5.5 metres
Weight: 6,000kg
Movement: Bipedal
Feeding Type: Carnivore

Information:
- Discovery: Acrocanthosaurus is a theropod dinosaur, which existed in what is now North America during the Early Cretaceous period. The first two fossil specimens of Acrocanthosaurus were found in the early 1940s, and consist of two partial skeletons along with a piece of cranial material. The bones were recovered from the Antlers Formation in Oklahoma, USA and were both described and named in 1950 by American palaeontologists J. Willis Stovall and Wann Langston. Two much more complete specimens were described in the 1990s. The first is a partial skeleton, missing most of the skull, which was recovered from the Twin Mountains Formation of Texas, USA. The second was an even more complete skeleton, recovered from the same rock formation as the holotype specimens, and nicknamed ‘Fran’ by researchers. ‘Fran’ is currently housed at the North Carolina Museum of Natural Sciences in Raleigh, USA. This specimen is the largest Acrocanthosaurus individual to have been discovered and includes the only known complete skull and forelimb.  
            Acrocanthosaurus has been the topic of much debate regarding its placement within the theropod family. The original description was based upon only fragmentary remains, leading to highly variable initial classifications. J. Willis Stovall and Wann Langston first placed Acrocanthosaurus within the theropod sub-family, allosaurid; although it was soon moved to the megalosaurid sub-family by palaeontologist Alfred Sherwood Romer in 1956. For the following 20 years many authors classified Acrocanthosaurus as a spinosaurid due to similarities between the large vertebrae of Spinosaurus and those of Acrocanthosaurus. Recent analyses have found Acrocanthosaurus to be a fairly basic carcharodontosaurid, closely related to the African Carcharodontosaurus and Giganotosaurus from South America.

- Statistics: Acrocanthosaurus was one of the largest theropods to have ever existed. The largest known individual measured 11.5 metres in length from snout to tail tip; with the skull alone measuring nearly 1.3 metres in length. Recent estimates have suggested that Acrocanthosaurus would have weighed around 6,000kg. 19 curved, serrated teeth lined each side of the upper jaw; and although an accurate lower jaw tooth count has not been published, it is estimated that the jaw of Acrocanthosaurus housed around 68 teeth in total.

- Description: Acrocanthosaurus is primarily known for the high neural spines which protrude from many of its vertebrae. These spines grew to almost 2.5 times the length of the vertebrae which they extended from, and had attachments for powerful muscles. These muscles formed a tall, thick ridge running down the back of the dinosaur, similar to that seen in modern-day bison. The exact function of this muscular ridge is still unknown, although it is suggested that is was involved in interspecies communication, fat storage or even temperature control.
            Aside from its vertebrae, Acrocanthosaurus had a fairly typical carcharodontosaurid skeleton. It was a bipedal carnivore, with a long, heavy tail counterbalancing the head and body, maintaining its centre of gravity over the hips. Unlike many smaller fast-running dinosaurs, its femur was longer than its tibia and metatarsals, suggesting that Acrocanthosaurus was not a fast runner. The discovery of a complete Acrocanthosaurus forelimb allowed a unique analysis of the function and range of motion of a theropod forelimb. The study suggested that the shoulder and elbow of Acrocanthosaurus was limited in its range of motion compared to that of humans; with the elbow having a total range of motion of only 57°. After determining the ranges of motion in the joints of the forelimb, the study went on to hypothesise about the predatory habits of Acrocanthosaurus. The forelimbs could not swing forward very far, and therefore were not likely to have been used in the initial capture of prey; meaning Acrocanthosaurus probably led with its mouth when hunting. On the other hand, the forelimbs were able to retract towards the body very strongly. Once prey had been seized in the jaws, the heavily muscled forelimbs may have retracted, holding the prey tightly against the body and preventing escape. As the prey animal attempted to pull away, it would only have been further impaled on the permanently flexed claws of the first two digits.


Top Picture Source: tavari (deviant art)
Bottom Picture Source: shartman (deviant art)

 

Name: Achillobator
Pronounced: Ah-Kill-Oh-Bait-Ore
Classification: Theropod
Sub-family: Dromaeosaurid
Temporal Range: Late Cretaceous (90 Mya)
Length: 6 metres
Height: 2 metres
Weight: unknown
Movement: Bipedal
Feeding Type: Carnivore

Information:
- Discovery:Achillobator is a genus of dromaeosaurid dinosaur from the Late Cretaceous period of modern-day Mongolia. The first fossil remains of Achillobator were discovered in 1989, although these were not described and named until 1999, by Mongolian palaeontologist Altangerel Perle, and Americans Mark Norell and Jim Clark. The fossil bones themselves belong to a single individual and were found mostly disarticulated. Bones discovered include a fragment of the upper jaw (with teeth), vertebrae from all spinal sections, ribs, and bones from the shoulder, pelvis, forelimbs and hindlimbs.
            Although researchers are fairly sure that Achillobator is a dromaeosaurid, the lack of fossil material has made finding its exact place within this family fairly difficult. The general consensus is that Achillobator is a member of the subfamily dromaeosaurine; making it more closely related to the North American dinosaur, Utahraptor, rather than to other dromaeosaurids, such as Deinonychus and Velociraptor.
                       
- Statistics: The holotype specimen of Achillobator is a fairly large individual, and researchers have estimated its body length at around 6 metres; which is exceptionally big for a dromaeosaurid. Its size is very similar to that of Utahraptor, hence the proposed close relationship suggested above.

- Description: Achillobator was a bipedal predator that, given its large size, would have been relatively high up within its ecosystems food-chain. Like all dromaeosaurids it is suggested that Achillobator hunted with a large, sickle-shaped, claw situated at the end of the second toe of each hind foot.
            One characteristic that distinguishes Achillobator from other dromaeosaurids is that of its hip bone. The pelvis displays a number of very primitive characteristics when looked at in comparison with those from other dromaeosaurids. It is aligned almost vertically and has a large pubic boot (a wide expansion at the end). In addition, the pubis points backwards in the same direction as the ischium (a condition called opisthopuby), which is seen in the unrelated therizinosaurids and ornithischians. These differences have led to suggestions that Achillobator represents a palaeontological chimera (a fossil which has been reconstructed with elements coming from more than a single genus). Other research has suggested that these differences may mean that Achillobator in fact represents an entirely new type, and classification, of dinosaur. Currently, Achillobator is classified as a dromaeosaurid and will continue to be classed as such until new, related, fossil material is discovered.


Top Picture Source: T-PEKC (deviant art)
Bottom Picture Source: Matt Martyniuk (taken from Wikipedia)

Name: Achelousaurus
Pronounced: Ah-Kee-Low-Saw-Russ
Classification: Ceratopsid
Sub-family: Centrosaurine
Temporal Range: Late Cretaceous (74 Mya)
Length: 6 metres
Height: 2.7 metres
Weight: unknown
Movement: Quadrupedal
Feeding Type: Herbivore

Information:
- Discovery: Achelousaurus is a ceratopsid dinosaur, which is known from a number of specimens recovered from a huge bonebed in the Two Medicine Formation in Montana, USA. Three skull fossils, along with a plethora of postcranial material are currently housed at the Museum of the Rockies in Bozeman, Montana.
            Achelousaurus itself was first described, and named, in 1995 by palaeontologist Scott Sampson. Sampson classified Achelousaurus as a centrosaurine ceratopsid, although more specifically as a pachyrhinosaurine (a sub-family of centrosaurines which includes Einiosaurus and Pachyrhinosaurus).
           
- Statistics: Research has suggested that a fully-grown Achelousaurus would have reached around 6 metres in length; with 1.6 metres of total body length being attributed to the skull alone. These measurements make Achelousaurus a fairly standard, medium-sized ceratopsid.

- Description: Upon first discovery Achelousaurus looked very similar in body shape to other North American ceratopsians; especially Pachyrhinosaurus. The similarities between these two animals had led many researchers to suggest that Achelousaurus in fact represents a species of Pachyrhinosaurus, and therefore does not warrant its own genus. The main likeness between these two dinosaurs are the raised bony areas (known as bosses) found within the facial area.
            Achelousaurus had a parrot-like beak and a rough boss on the snout, as opposed to the nasal horn found on other ceratopsians such as Triceratops and Centrosaurus. This lump of bone is slightly smaller than the one seen in Pachyrhinosaurus and is very deeply wrinkled. As the animal grew older this nasal boss grew taller and began to point slightly forwards. Achelousaurus also has two more raised bony areas above its eyes, and it is suggested that the bosses were used for interspecies combat. Achelosaurus also sports a pair of horns, which are flattened in cross-section, and protrude from the back of the frill, splaying outwards.  

Top Picture Source: Sergey Krasovskiy (Deviant Art)
Bottom Picture Source: Science Photo Library

Name: Abrictosaurus
Pronounced: Ah-Brick-Toe-Saw-Russ
Classification: Ornithischian
Sub-family: Heterodontosaurid
Temporal Range: Early Jurassic (199-196 Mya)
Length: 1.2 metres
Height: 0.4 metres
Weight: 45kgs
Movement: Bipedal
Feeding Type: Herbivore

Information:
- Discovery:Abrictosaurus is a small, bipedal ornithischian dinosaur which is known from the fossil remains of only two individuals.  These remains, which include two skulls and some varied fragmentary bones, were discovered in the Upper Elliot Formation of Qacha’s Nek District in Lesotho and Cape Province in South Africa, respectively.
            Both specimens were discovered by palaeontologist Richard Thulborn, who in 1974 first described the specimens as possible female examples of Lycorhinus. This theory was later disputed by fellow palaeontologist James Hopson; whose research suggested that the two specimens found by Thulborn had too many skeletal variations to those of Lycorhinus, and therefore warranted their own separate genus. Later in the year Hopson created a new genus to contain both specimens; Abrictosaurus. Both specimens of this dinosaur are currently housed within the collection of University College London.
           
- Statistics: Abrictosaurus is only really known from the two skull fossils discovered; however comparisons of these skulls with those of close relatives (such as Heterodontosaurus and Lycorhinus), have allowed researchers to estimate Abrictosaurus’ fully grown body length at around 1.2 metres and overall body weight at about 45kg.

- Description: Heterodontosaurids like Abrictosaurus were small, herbivorous ornithischians, who were known best for being heterodonts (animals which possessed more than a single tooth morphology). The heterodontosaurids had large, canine-like tusks (called caniniforms) in both the upper and lower jaws. Abrictosaurus is often considered the most basic member of the heterodontosaurid family, and because of this it is often said that Abrictosaurus was so primitive that it lacked tusks. This is not the case, as caniniforms were clearly present on one of the two fossil skulls discovered. The upper caniniform measured 10.5mm in length, while the lower reached 17mm. Unlike the caninforms of Lycorhinus and Heterodontosaurus, which were serrated on both sides, the tusks found in Abrictosaurus were only serrated on the anterior edge. Despite these large caniniforms, the front of the jaw housed no teeth and instead consisted of a hard beak like structure which would have been used to crop plant material.
            The fact that caniniforms were only discovered in one of the two Abrictosaurus fossils has led many researchers to suggest that heterodontosaurids were sexually dimorphic; with only males supporting tusks, similar to modern day animals such as walrus’, Asian elephants and musk deer. However, because very few bones were discovered alongside the skulls, it is impossible to tell the exact size of each individual and therefore the fossil which displays no caniniforms could in fact be that of a juvenile, rather than a female. This would suggest that the lack of tusks was a juvenile trait instead of a secondary sexual characteristic. Until more fossils are unearthed the debate over sexual dimorphiosm in heterodontosaurids will continue.

Top Picture Source: Unknown (Taken from Wikipedia)
Bottom Picture Source: Science Photo Library

Name: Abelisaurus
Pronounced: Aye-Bell-Ee-Saw-Russ
Classification: Theropod
Sub-family: Abelisaurid
Temporal Range: Late Cretaceous (80 Mya)
Length: 6.5 metres
Height: 2.2 metres
Weight: 1,400kgs
Movement: Bipedal
Feeding Type: Carnivore

Information:
- Discovery:Abelisaurus is a carnivourous theropod dinosaur, which lived during the Late Cretaceous Period of what is now South America. It is known from a single, partial skull fossil which was unearthed by Argentinian palaeontologist, Roberto Abel. Abelisaurus was first described in 1985 by Jose Bonaparte and Fernando Novas; who decided that, at the time of description, the animal did not fit into any of the theropod sub-families. This led to the creation of the abelisaurid family group of theropods; a group which includes notable meat-eaters, Carnotaurus and Majungasaurus.
           
- Statistics: The single known fossil skull of Abelisaurus is incomplete, especially on the right side and is also missing most of the palate (roof of the mouth). Despite these absent pieces, the skull itself measures 85cm in length and researchers have used these skull dimensions to estimate the animal’s fully-grown body length at around 6.5-7 metres.

- Description: The main striking characteristic of Abelisaurus is the abundance of large, window-like, holes within its skull. These holes are referred to as fenestrae, and although common in many dinosaurs, Abelisaurus has a considerable large fenestrae just above the jaw; in front of the eyes. These holes were thought to have evolved as a weight-saving mechanism; lightening the weight of the head of large theropods, which otherwise might have unbalanced the entire body. Many abelisaurids supported bony crests or horns along the top of the skull; although none of these are seen on the Abelisaurus skull fossil discovered. There are a number of rough ridges (along the snout and above the eyes), which may have supported some form of keratin crest, which would not have fossilised. 

Picture Source: Science Photo Library
Skull Picture Source: Christofersen (Deviant Art)