Aardonyx

Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Aardonyx means “earth” in Afrikaans and “nail, claw” in Greek.

Some incomplete fossils were found in South Africa and paleontologists stated in 2010 that the discovery had helped fill a gap in the evolution of sauropods as it showed how two legged animal started to get the features needed so sauropods could spend a life on four legs. Ardonyx filled some gaps and confirmed scientists theories which is why it was an important discovery.

The restoration picture shows how these dinosaurs were evolving from being bipedal (using two legs to walk on).

Scientists think the Aardonyx fossil discoveries were from dinosaurs that were under 10 years old. They found remains of vertebrae, dorsal and cervical ribs, gastralia, chevrons, elements of the pectoral and pelvic girdles, and bones of the fore and hind limbs It is thought Aardonyx was a powerful but slow walker.

FURTHER READING AND STUDY 

• Adam Yates et al (2009) A new transitional sauropodomorph dinosaur
• Riley Black (2009) The “Earth Claw” 
• Dr M Bonnan (2009) The Evolving Palaeontologist

Abelisaurus

Jordan Mallon, CC BY-SA 2.5, via Wikimedia Commons

Abelisaurus means “Abels lizard” and was named by Argentine paleontologists Jose Bonaparte and Fernando Novis in 1985 after Roberto Abel who discovered the specimen type.

The discovery was of a skull only which was badly damaged. It was a predatory dinosaur alive during the Late Cretaceous Period. Abelisaurus is the first dinosaur from the Abelisauridae group of carnivorous theropod dinosaurs, which mainly lived in the southern continents that we now know as Africa and South America.

It is thought the Abelisaurus had extremely small arms compared to other theropods.

Scientists have done full body reconstructions based on other dinosaurs from the Abelisauridae group which showed them it was a medium to large theropod and like many others was bipedal. Its amazing what information can be extracted from incomplete fossils.

FURTHER READING AND STUDIES

• J Bonaparte et al (1985) Abelisaurus Comahuensis
• N Longrich (2017) An Abellisaurid from the latest Cretaceous of Morocco
• R Martinez (2004) Abelisaurid remains from southern Patagonia

Achelousaurus

Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Achelousarus lived in North America during the Late Cretaceous Period and the first remains were discovered in 1987 by American paleontologist Jack Horner. The specific name refers to Horner himself and there were more discoveries made of Achelousaurus in 1989 and 1994.

Achelousarus had two horns at the top of the skull and a bony knob over its nose. The length of a fully grown Achelousarus’s skull is over 5 feet (1.6 meters) in length which would have been a very intimidating sight.

It is thought by some scientists that these dinosaurs lived in herds, this was due to bone fragments of multiple members of the ceratopsian species being found together and it was assumed in that find that they had been killed in either a flood or a drought.

FURTHER READING AND STUDY

• R Barrick et al (1996) Comparison
• A McDonald (2011) A subadult specimen 
• J Wilson et al (2021) Comparative cranial osteology  

Achillobator

Durbed, line drawing by Pilsator, CC BY-SA 3.0, via Wikimedia Commons

Achillobator was a smaller cousin to the Utahraptor, but much bigger than Velociraptor. They had extremely sharp and powerful foreclaws which were used to shred any armour that its prey might have had at speed. 

It has been illustrated that the Achillobator had a coat of feathers but this is not down to any fossil evidence, its theory is based on its evolutionary relationships with modern birds. 

The first fossil of Achillobator was found in 1989 during an exploration in South Central Mongolia. It was stored away only for it to be examined by several Palaeontologists and given its official name ten years later in 1999. 

The name means “Achilles hero” in Greek.       

FURTHER STUDY AND READING

• S Phil et al (2007) A method for distinguishing dromaeosaurid 
• P Senter et al (2012) New dromaeosaurids from Lower Cretaceous 
• R Ely et al (2019) Phylogeny of a new gigantic paravian

Acrocanthosaurus

Mariolanzas, CC BY-SA 4.0, via Wikimedia Commons

One of the most stunning dinosaurs, Acrocanthosaurus had a set of tall spikes that ran all the way down it’s spine around the neck area. Acrocanthosaurus is also believed to have had spikes on its hips and around its long upper tail. The spikes found on this dinosaur were big, but not as big as Spinosaurus’s.

Acrocanthosaurus also had quite a unique way of communicating to either attract mates or to warn off other Acrocanthosaurus during the mating season. Some scientists believe that it would stand up as high as it could taking in as much air as possible before releasing the air, making a deep noise from within its rib cage.

FURTHER READING AND STUDY

• P Currie et al (2000) A new specimen of Acrocanthosaurus
• J Harris (1998) A reanalysis of Acrocanthosaurus 
• J Stovall (1950) Acrocanthosaurus atokensis

Aegyptosaurus

Levi bernardo, CC BY-SA 3.0, via Wikimedia Commons

Aegyptosaurus is Greek for “Egypts lizard” and this dinosaur lived in Africa during the Late Cretaceous Period. Its actually a close relative to the ginormous sauropod Argentinosaurus that lived in South America but it was a smaller relative as you will see when you compare the two.

Aegyptosaurus was given its name by a German palaeontologist named Ernist Stomer in 1932 as its fossils were found in Egypt and the Sahara desert. 

Unfortunately during World War 2 the fossils were destroyed in an allied bombing raid as the fossils were kept in a museum in Munich. Only fragments survived.

Its possible Aegyptosaurus was hunted by Carcharodontosaurus as fossil remains have been found in similar locations but there is no evidence of this. 

FURTHER READING AND STUDY

• J Smith et al (2001) A giant sauropod dinosaur 
• H Atfy et al (2019) Repeated occurrence 
• N Ibrahim et al (2016) Evidence of a derived titanosaurian 

Afrovenator

PaleoEquii, CC BY-SA 4.0, via Wikimedia Commons

Afrovenator, the “African hunter’s” fossils were first discovered in Niger, Africa in 1993. Its named using the Latin afer meaning “African” and venator meaning “hunter”.

The skeleton found meant Afrovenator was the most complete predatory dinosaur from the Cretaceous period discovered in Africa. 

It is thought that Afrovenator was a cousin to Allosaurus, that lived in North America, and reconstructions have shown that it was a predator built for speed. A sauropod that was from the same time was Jobaria, and while no scientific proof has been discovered its possible that Afrovenator hunted it. 

FURTHER READING AND STUDY

• P Sereno et al (1994) Early Cretaceous dinosaurs from the Sahara
• R Allain (2002) Discovery of megalosaur
• P Sereno et al (2004) New dinosaurs link southern landmasses

Agilisaurus

Danny Cicchetti, CC BY-SA 4.0, via Wikimedia Commons

Agilisaurus was discovered in Asia and it was a bipedal runner (it ran on two feet) that was thought to be really fast. This was due to the dinosaur having no armour which meant it was exposed to predators and so its defence was speed and agility. Agilisaurus was a herbivourous and used its beak like structure jaw to help it consume plants. 

It had a long tail which was used for balance and studies completed think that Agilisaurus was an active dinosaur in the daytime and rested at night.

Interestingly the only complete skeleton was only discovered in the reconstruction of the Zigong Dinosaur Museum in China in 1984 and was named in 1990 by  Chinese palaeontologist Peng Guangzhou. The skeleton came from Dashanpu Quarry which is one of the richest quarry’s in dinosaur fossils ever discovered.  

FURTHER READING AND STUDY

• G Peng (1992) Jurassic ornithopod Agilisaurus
• P Barrett et al (2005) Small-bodied ornithischian dinosaurs 
• F Knoll et al (2008) Gongbusaurus and the early phylogeny

Alamosaurus

Петр Меньшиков, CC BY-SA 4.0, via Wikimedia Commons

You can tell by looking at the measurements that Alamosaurus was an enormous dinosaur. Some scientists estimated it could have been up to 30 meters (98ft) in length as most of the fossils were either of juvenile or small adult specimens. This  suggests it could have been in comparable size to other sauropods such as Argentinosaurus.

It lived in what is now the southern part of North America and scientists believe it was amongst the last surviving non-avian dinosaur species. 

There is a restored Alamosaurus skeleton mounted at the Perot Museum in Dallas. It was discovered when a member of an excavation team was working at a nearby fossil site. The member had to go around the other side of the hill they were working on as he had to “answer natures call”. A remarkable story and the restoration is impressive.       

FURTHER READING AND STUDY 

•  T Lehman et al (2002) A juvenile specimen of the sauropod dinosaur 
• S Lucas et al (1989) Alamosaurus and the sauropod hiatus 
• R Tyoski et al (2017) An articulated cervical series of Alamosaurus 

Albertaceratops

Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Albertaceratops name means “horned face”, and as the name and picture shows this dinosaur had very prominent horns above its eyes, that curved out to the sides.  There is only one ever finding of Albertaceratops and all is known from a single complete skull that was discovered in August 2001 in Canada.

There was further fossils found in the river bed in Montana but these were later ruled out to be a different dinosaur. 

The skull of Albertaceratops is on display in the Phillip J. Currie Dinosaur Museum in Canada and it was formally named in 2007 by Michael Ryan after he did  genetic analysis of the skull. Later family members of the group would develop considerably reduced brow horns.  

Albertaceratops was a herbivore and its full species name of Albertaceratops A. nesmoi is based on a rancher named Cecil Nesmo who has aided fossil hunters in the past. 

FURTHER READING AND STUDY 

• K Chiba et al (2016) Re-evaluation of Medusaceratops
• M Ryan et al (2010) A new chasmosaurine ceratopsid 
• S Sampson et al (2013) A remarkable short-snouted horned dinosaur

Albertosaurus

Nobu Tamura email:nobu.tamura@yahoo.com http://spinops.blogspot.com/ http://paleoexhibit.blogspot.com/, CC BY-SA 4.0, via Wikimedia Commons

Albertosaurus was a much smaller tyrannosaurid relative of the Tyrannosaurus rex, but was a bipedal (two-legged) predator in its own right that lived in the western North America but fossils of an indeterminate species have also been discovered in Mexico. 

It was discovered in 1884 and named in 1905 and since the first discovery over 30 fossils of Albertosaurus have been discovered.

26 were found at one sight which meant scientists say that was evidence of pack behaviour. 1,128 fossil bones of Albertosaurus have been discovered, and is the largest number of any theropod  bones from the Cretaceous Period. In fact scientists have been able to see the effects of diseases and parasites that were found on some individuals. This group found were aged between 2 years old and 23 years old and the oldest specimen that has been found was 28 years old.

Albertosaurus has been described to reach walking speeds of 14 – 21km/hour (8-13 mph) with running speeds a lot higher. 

FURTHER READING AND STUDY 

• F Therrien et al (2021) Mandibular force profiles and tooth morphology
• L Buckley et al (2010) Quantifying tooth variation
• R Bell et al (2010) Palaeopathological changes in Albertosaurus

Alectrosaurus

Conty, CC BY-SA 4.0, via Wikimedia Commons

Alectrosaurus was a tyrannosauroid theropod dinosaur that lived in Asia and was thought to be a very fast predator that was able to hunt down his prey with devastating efficiency. 

If we had a third description of the type of dinosaur then Alectrosaurus would have been a Medium sized theropod as it was not as big as Tyrannosaurs rex but was not small either. 

Alectrosaurus was discovered in 1923 by an expedition of the American Museum of Natural History that was searching for dinosaur fossils in Mongolia. During this expedition two discoveries were made 30 meters apart from each other by an assistant palaeontologist George Olsen. These fossil specimens were only named in 1933 by American palaeontologist Charles Gilmore. 

The name Alectrosaurus means “alone lizard” and the specific name Alectrosaurus olseni was in recognition of George Olsen who discovered them.   

Its believed Alectrosaurus lived alongside theropods such as Achillobator, Garudimimus or Stegnosaurus. 

FURTHER READING AND STUDY 

• B Mader et al (1989) A redescription and revised diagnosis
• N Kramarenko et al Joint Soviet- Mongolian Paleontological expedition
• J Hurum et al (2003) Skull structure and evolution in tyannosaurid dinosaurs

Alioramus

Fred Wierum, CC BY 3.0, via Wikimedia Commons

Alioramus was a bipedal (two-legged) theropod dinosaur that lived in Asia and was discovered in the early 1970’s by a joint Soviet-Mongolian expedition and was named in 1976 by Russian palaeontologist Sergei Kurzanov.

Since it was first discovered there was a lot of consideration that Alioramus was in fact a juvenile of the larger Tarbosaurus due to the small amount of fossils obtained. But when the second species was discovered in 2009 they found more evidence to keep Alioramus in its own separate genus as it had more teeth and a series of five crests on the top of its snout.

The name Alioramus translates as “different branch” and was named this as Alioramus’s head and body was different to other tyrannosauroids. Its estimated size is also an area of contention because without fossils from a fully grown Alioramus its very hard to be certain the estimates are correct.       

FURTHER READING AND STUDY 

• G Bever et al (2011) Variation, Variability, and the origin
• M Gold et al (2013) The cranial pneumatic sinuses of the tyrannosaurid 
• S Brusatte et al (2009) A long-snouted, multihorned tyrannosaurid 

Alvarezsaurus

User:Karkemish, CC BY 3.0, via Wikimedia Commons

Alvarezsaurus was a small dinosaur that lived in Argentina and discovered in 1991 in a place called Bajo de la Carpa Formation, where many fossils have been discovered. It was named after the Argentinian writer and historian Don Gregorio Alvarez, as Alvarezsaurus means, “Alvarez’s lizard”.

It was named by palaeontologist Jose Bonaparte who has been described by American palaeontologist as “almost singlehandedly responsible for Argentina becoming the 6th country in the world in kinds of dinosaurs”.    

Alvarezsaurus was a lightweight theropod that moved around on its two hind legs (bipedal) and was thought to be a fast runner and used its long tail for balance. It was thought to have an enlarged finger with a large claw. Scientists have thought that this was to enable Alvarezsaurus to use it to put holes into termite mounds which would allow it to feed off individual termites. But there is no evidence to support this hypothesise.  

FURTHER READING AND STUDY 

• T Holtz et al (2018) Evolution: New branches on the alvarezsaur tree
• L Chiappe et al (2002) The Cretaceous, short armed Alvarezsauridae
• F Novas (1997) Anatomy of Patagonykus  

Amargasaurus

© N. Tamura | nobu.tamura@yahoo.com | http://spinops.blogspot.com | http://paleoexhibit.blogspot.com, CC BY-SA 4.0, via Wikimedia Commons

Amargasaurus was discovered and lived in what is now Argentina and the only discovery was made in 1984 where the fossils found meant there was a near complete skeleton. It was found on the 8th expedition of a project called “Jurassic and Cretaceous Terrestrial Vertebrates of South America” which started in 1975 to improve the knowledge of dinosaurs in that region. These expeditions were also supported by the National Geographic Society   

As sauropods come Amargasaurus was small in comparison and was first unofficially mentioned in an Italian book in 1984. Its first official description wasn’t until 1991 in an Argentinian scientific journal.

Amargasaurus moved on all four legs and it was suggested in the 1991 journal that it was a slow walker due to its forearms and lower legs being proportionally short.

Amargasaurus was a herbivore and it shared its environment with three other sauropods and so it may have had different food sources to enable it to eat.

FURTHER READING AND STUDY 

• A Paulina et al (2014) Braincase, neuroanatomy, and neck posture of Amarasaurus
• P Gallina et al (2019) A new long-spined dinosaur from Patagonia
• G Mazzetta et al (2004) Giants and bizarres 

Ammosaurus

Leví Bernardo Martínez, Copyrighted free use, via Wikimedia Commons

Ammosaurus means “sand lizard” in Greek and refers to the sandstone in which it was discovered in Connecticut, North America in 1884 by quarry workers. Now unfortunately the front half of the skeleton was used in the construction of the South Manchester Bridge as it was taken away unknowingly. 

The rear half was taken by the American palaeontologist Othniel Charles Marsh. But what’s fascinating about this story is the Ammosaurus remains that went into the construction of the bridge, were actually partially reclaimed in August 1969 when the bridge was decommissioned and demolished by American palaeontologist John Ostrom. 

Marsh named the fossil in 1891 as Ammosaurus major having two years previously named it Anchisaurus major only to change his findings. 

FURTHER READING AND STUDY  

• P Galton (1971) The prosauropod dinosaur Ammosaurus
• E Fritzer et al (2006) Dinosaurs of the Connecticut valley
• T Fedak et al (2007) Description and evolutionary significance 

Ampelosaurus

ДиБгд at Russian Wikipedia, Public domain, via Wikimedia Commons

Ampelosaurus was discovered in France and its names means “vineyard lizard” in reference to the location where it was found. Named by French palaeontologist Jean Le Loeuff in 1995 it was a significant find because aside from Almosaurus, Ampelosaurus one of the only known sauropods that lived in the Late Cretaceous period. 

Species that was found, were four times as small as others and scientists believe this was because it was trapped on Islands and so needed to adapt to survive on the reduced vegetation it had available. They had called this island dwarfism and was found to be similar to other dinosaurs that lived on the same islands.

Ampelosaurus was a slow, long necked, large dinosaur that interestingly had armour like plating all the way down its back. Scientists think this was for extra protection against predator sauropods powerful jaws.  

FURTHER READING AND STUDY  

• N Klein et al (2012) Modified Laminar Bone in Ampelosaurus 
• F Knoll et al (2013) Neurocranial Osteology and Neuroanatomy 
• J Loeuff (2005) Osteology of Ampelosaurus 

Amygdalodon

Levi bernardo, CC BY-SA 3.0, via Wikimedia Commons

Amygdalodon was a sauropod discovered in Argentina in 1936. The discovery consisted of partial fossils of including a couple of ribs, part of the pelvis, shoulder blade, some teeth and vertebrae. It wasn’t officially named until 1947, before 1936 Sauropods in Argentina were unknown. 

The name Amygdalodon means “almond tooth” as its teeth that were discovered were oval in shape and in a study in 2018 Amygdalodon was concluded to be a sister to Isanosaurus. 

Amygdalodon used all four legs to weight bear and manoeuvre and was also a herbivore.   

FURTHER READING AND STUDY 

• J Carballido (2010) The dentition of Amygdalodon patagonicus   
• O Rauhut (2003) Revision of Amygdalodon 
• C Jose, D Pol The dentition of Amygdalodon

Anchiceratops

Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Anchiceratops was discovered in what is now Canada in 1912 by an expedition and was named as the genus name of Anchiceratops, which means “near horned face” in 1914 by American palaeontologist Barnum Brown.   

Anchiceratops like other ceratopsians was a herbivore that moved on all four limbs and it had three horns on its face, two were situated above the eyes and the third was on its snout.

Another feature was its very distinctive frills. These were wide and had bony knobs located on either side of the midline and pointing sideways and varied in size depending on the size of the individuals.

Anchiceratops was a longer lived dinosaur than other species and this was maybe due to lower dinosaur density in the area it lived which meant it would have had  less competition for food. Or it may have been because Anchiceratops was better at coping with environmental changes.

Anchisaurus

Nobu Tamura (http://spinops.blogspot.com), CC BY-SA 3.0, via Wikimedia Commons

Anchisaurus was first discovered in 1818 while a well was being excavated by gunpowder in Connecticut, United States. It was originally thought that these bones were of a human. A similar story happened in 1855 when a well for an American armoury in Springfield was being excavated. On both occasions fossil specimens were severely damaged due to the blasting, and bones were accidentally thrown away by the construction workers or kept by onlookers. This meant that these dinosaurs were only known from incomplete fossils.

Anchisaurus as you will see from the table was a small dinosaur and so the initial confusion with human bones was easily made back then. It is classed as a sauropod but was originally classed as a prosauropod, which was a group of dinosaurs related to sauropods, but recent investigations showed it was closer to sauropods.

Its family of Anchisauridae was first described by Othniel Charles Marsh in 1885 but this group is not used in the most current classifications.    

Ankylosaurus

DataBase Center for Life Science (DBCLS), CC BY 4.0, via Wikimedia Commons

Ankylosaurus was one of the largest armoured dinosaurs known. Its appearance was frightening, not that put off predators of its time included Tyrannosaurus Rex. It roamed the earth 68 to 66 million years ago in western North America and Canada.

Ankylosaurus is Greek for “fused lizard”, and as the name suggests the reason was down to the fused bones in its skull and other bones.

Ankylosaurus fossils has been found in the famous American location of the Rocky Mountains which during the Cretaceous periods were a warm and subtropical climate that was rich in vegetation. There was probably tropical storms, with monsoon like weather.

Ankylosaurus shared the dinosaur rich habitat with plenty of others. Some were friendly, such as Triceratops who was around during this period and was also a herbivorous, and others were not. Ankylosaurus needed all its armour with quick and fierce predators around such as the Tyrannosaurus rex who patrolled the locations at the same time. Although the T- Rex would have had to be very brave to take on the Ankylosaurus due to its size and tough armour.

Anserimimus

Eduard Solà, CC BY-SA 3.0, via Wikimedia Commons

Anserimimus was named in 1988 and found in Mongolia when a Soviet – Mongolian expedition took to the desert in the late 1970’s. Anserimimus means “goose mimic” and was given its name by Mongolian palaeontologist Rinchen Barsbold. It did not resemble much of a goose but other dinosaurs had been named after other birds. Its fossil remains consisted of an incomplete skeleton and was missing its skull and lower jaw.

Anserimimus had long and powerful arms, it is still not proven as to why but scientists seem to think this may have been for gathering food. It had 5 bones that were fused together which would only have added to its strength. Apart from its strong arms it is likely it closely resembled other ornithomimids.  

As there is no full fossils of the skull its still not clear what Anserimimus ate although it probably lived around shallow lakes, rivers, and streams.      

Antarctosaurus

No machine-readable author provided. Murraybuckley assumed (based on copyright claims)., Public domain, via Wikimedia Commons

Antarctosaurus lived in South America which is why its name “southern lizard” was given to the dinosaur in 1929 by French palaeontologist Friedrich von Huene. Although this was 17 years after the original remains were discovered in 1912 in Argentina.   

As the picture demonstrates the estimated size of Antarctosaurus compared to a human. Antarctosaurus was a large sauropod that had a large tail and neck. Some scientists believe it was also armoured and several species have been found over the years including Antarctosaurus giganteus or A. giganteus for short. Some studies have shown that this species was much smaller that Argentinosaurus. 

There have been controversies surrounding different named species associated with Antarctosaurus which have been discovered in India and Kazakhstan for example, which some are seen as incorrect.   

What we do know for sure is this dinosaur was large, it ate plantation, and walked on all four limbs making it a “quadrupedal herbivore”.  

FURTHER READING AND STUDY 

• J Wilson et al (2009) Reassessment of sauropod dinosaur
• G Mazzetta et al (2004) Distal tail segment of a titanosaur
• M Szermanski et al Antarctosaurus 

Apatosaurus

Durbed, CC BY-SA 3.0, via Wikimedia Commons

Apatosaurus or ‘Brontosaurus’ was another giant sauropod that lived around the same time as Brachiosaurus between 155.7 to 150.8 million years ago, during the Jurassic Period.

Palaeontologists believe that Apatosaurus (‘Brontosaurus’) reached lengths of 70-75ft in length which is around 21-23 meters, so certainly not a small dinosaur. In terms of weight, Apatosaurus (‘Brontosaurus’) is estimated to weigh up to 39 tons which is roughly the same as 16 Elephants.

Apatosaurus was first discovered in 1877 and named by Othniel Charles March who was a Professor of palaeontology at Yale University who named it “deceptive lizard”. The name was down to the similarities of mosasaurs rather than other dinosaurs.

The connection with mosasaurs was initially due to the thought process that it was too big to support its own weight on land but more recent studies have not supported this. 

Aragosaurus

Levi bernardo, CC BY-SA 3.0, via Wikimedia Commons

Aragosaurus like most other sauropods had a long neck and a long tail, it had slightly smaller front legs than rear, and was named in 1987 after being discovered in Spain. The fossils found consisted of femur, pubis, ischium, phalanges, scapula, and tail vertebrae. 

Its thought that Aragosaurus was able to use its reach to get up to higher plantation and tree tops that other dinosaurs could not. Its teeth were large and wide which meant Aragosaurus would have been able to slice through leaves and branches of conifer trees. 

There has been a lot of comparisons with the North American sauropod, Camarasaurus, and also has given scientists thoughts that the two continents of Western Europe and North America were still joined by the late Jurassic period. 

Aralosaurus

Hypsilophodon foxii, CC0, via Wikimedia Commons

Aralosaurus was a dinosaur that lived in what’s now Kazakhstan and was identified by only couple of bones. They were discovered in 1957 when there was a Soviet expedition and the only complete fossil bones were an upper arm and foot bone.

Aralosaurus was only named in 1968 when it was named and described by a Soviet palaeontologist named Rozhdestvensky. The fossils were revisited in 2004 but unfortunately some of the fragments that were first described had been lost. These were crucial in establishing the size and shape of Aralosaurus’s crest. The discovery of a more complete specimen is needed to provide better knowledge.

Aralosaurus name means “Aral lizard” and is named after the Aral sea which is located between Kazakhstan and Uzbekistan. 

Interestingly Aralosaurus had a low bulge in the front of its eyes and its thought that this meant it was able to inflate it and therefore able to produce a bellowing noise. Its thought this was either to warn and scare predators, or to attract mates. 

Archaeoceratops

Pracownia at English Wikipedia, CC BY 3.0, via Wikimedia Commons

Archaeoceratops was a dinosaur that was discovered in China in 1997 where they discovered an incomplete skeleton. It’s name was interpreted as “ancient horned face” and was small in comparison to other ceratopsians. It also had no horns but only a small bony frill that started from the back of its head.

It took a bipedal stance for walking but was thought to go on all fours to enable it to feed off low vegetation. Being a herbivore during the Cretaceous period there was thought to be very few flowering plants and therefore  Archaeoceratops’s diet may have included ferns, and conifers. It would have bitten off leaves or needles with its sharp beak and would have chopped them up before being consumed.

Like many other dinosaurs in its classification it had a parrot like beak .      

Archaeopteryx

DataBase Center for Life Science (DBCLS), CC BY 4.0, via Wikimedia Commons

Archaeopteryx was first discovered in 1860 or 1861 and it was only a single feather that was unearthed by a German palaeontologist Hermann von Meyer. This is a great example of how technology helps pervious discoveries because in 2019 laser imagery revealed structure of its quill and it was concluded that it was not a feather from Archaeopteryx. This was challenged in 2020.

The very first skeleton of Archaeopteryx was found in 1861 in Germany and it is thought this skeleton was swapped for medical services with a local physician. This was then sold to the Natural History Museum in London.

There have been more specimens that were discovered in Germany or Portugal with the latest being discovered in 2010 by an amateur collector at a quarry in Germany. It was only announced in 2014.

Archaeopteryx was the size of a modern day raven but unlike modern birds it had small teeth and a long bony tail.      

Archaeornithomimus

Audrey.m.horn, CC BY-SA 4.0, via Wikimedia Commons

Archaeornithomimus which in Greek means “ancient bird mimic” which is the perfect description of this dinosaur as it looks very much like an ostrich. So much so that Archaeornithomimus was classed as a ornithomimosauria theropod dinosaur.

Archaeornithomimus lived around 96 million years ago in the Late Cretaceous period. around 96 million years ago. Archaeornithomimus was a fair size and is estimated to have reached up to 3.4m or 11 ft in length and weighed up to 91kg or 200lb. Scientist also believe that Archaeornithomimus’s body would have been covered in feathers, and would have also had a beaked mouth.

Archaeornithomimus was discovered in 1923 Roy Chapman Andrews where a selection of bones were discovered from several individuals.

Argentinosaurus

Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Argentinosaurus  was a giant sauropod dinosaur and was perhaps the largest known land animal ever. Its length ranged from 30 to 40 meters (100 to 130 foot), and it weighed between 50 to 100 tonnes.

It was during the Late Cretaceous period that Argentinosaurus roamed the earth in Argentina 99.6 to 89.8 million years ago and was first discovered in 1987 by a farmer. This farmer informed the local museum thinking the fossils were petrified logs and they were exhibited in the museum.  

This then became an excavation site in 1989 and the palaeontologist in charge, Jose Bonaparte helped name Argentinosaurus which meant “Argentine lizard”.

The giant size of Argentinosaurus and other sauropods like it was possible due to a combination of things. Firstly they were energy efficient dinosaurs that allowed their long necks to move around, they had a very efficient digestive track that allowed them to keep food for lengthy periods to enable them to get maximum energy out of the plantations and help protect them from predators.  

Arrhinoceratops

Nobu Tamura (http://spinops.blogspot.com), CC BY-SA 3.0, via Wikimedia Commons

Arrhinoceratops which in Greek means “no nose-horn face” was a large three horned Dinosaur and belonged to the ceratopsian family.

The name ‘Arrhinoceratops’, particularly the Greek meaning, is a little confusing for two reasons. The first is that Arrhinoceratops did have three horns, and to add further confusion its name was originally given to it after the first fossilised discovery deemed its nose horn not to be a separate bone. However later studies of Arrhinoceratops skull deemed this theory to be incorrect. Alas, it was too late and the somewhat confusing name stuck.

Arrhinoceratops lived in the late Late Cretaceous period and was actually alive some three million years before the instantly recognisable Triceratops. Arrhinoceratops is estimated to have been 4.5 metres or 15ft in length and weighed as much as 1.3 tonnes or 2,900lb. Arrhinoceratops was first discovered in1923 with partial remains of a skull being found and wasn’t named until 1925 by William Arthur Parks.

Atlascopcosaurus

Bardrock, Public domain, via Wikimedia Commons

Atlascopcosaurus which means “Atlas Copco lizard” was a member of the iguanodont family of dinosaurs and was classed as a small bipedal herbivore. It was first discovered in 1984 in Australia but only named in 1989 by two Australian palaeontologists, Tom Rich and Patricia Vickers-Rich   

It is estimated that Atlascopcosaurus was around two to three metres (6.5–10 ft) long and weighed up to 125 kg. When compared to other iguanodont family members it was relatively small.

Atlascopcosaurus lived in what is now classed as Australia in the early Cretaceous period and was discovered in 1984. Though only a small amount of remains were discovered including part of the jaw and teeth.

Aucasaurus

Paleocolour, CC BY-SA 4.0, via Wikimedia Commons

Aucasaurus was closely related to Carnotaurus and looked fairly similar too, however it didn’t have horns like those found on Carnotaurus instead it has two low ridges above each socket. 

Aucasaurus wasn’t as big as Carnotaurus but was a mid-size predator. Scientist Gregory S. Paul estimated that Aucasaurus was around 5.5m in length and weighed around 700kg. So still a very sizable dinosaur, but around half the weight of Carnotaurus.

Aucasaurus also had very short arms that were pretty much useless. Most noticeably was that Aucasaurus hands which were a little different too. The most noticeable difference between Aucasaurus hands and its bigger brother Carnotaurus were that it had four Metacarpals, which are the lower finger bone in your hand, but didn’t have finger bones on it’s first and fourth. The second and fourth digits had finger bones but were short and had no claws… You can see why we’ve described them as being pretty much useless.

Austrosaurus

Levi bernardo, CC BY-SA 3.0, via Wikimedia Commons

Austrosaurus which means “Southern lizard” was classed as a titanosaurian sauropod and lived between 105-110 million years ago in the early Cretaceous period in what is now classed as Australia.

Very little is known about Austrosaurus as very little remains have been discovered. The first Austrosaurus were discovered in 1932 in Australia by a man called Mr. H.B. Wade and Austrosaurus was given its name a year later.

Austrosaurus is estimated to have been 20 meters long, around and weighed about 16,000 kg or 17 tonnes.

Austrosaurus was so large it sparked a great deal of debate among scientists as to whether these large titanosaurian sauropods lived in or around water to support their huge size. However, it is now widely accepted that this theory is incorrect and has been rejected by most of the scientific community, with the belief that these huge dinosaurs such as Austrosaurus lived on dry land.

Avaceratops

Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Avaceratops could be described as being a micro triceratops. This small herbivorous dinosaur was part of the ceratopsian dinosaurs family and would have lived during the Late Cretaceous Period 85 to 70 million years ago.

It is estimated that Avaceratops would have been between 2-4 meters in length (7-14ft) and could weigh up to a tonne. As is common in ceratopsian dinosaurs, Avaceratops had a frill on the back of its head and three horns on its face. Two horns would have been located just above the eye socket and one on the nose area. These facial horns are estimated to have been up to 25 centimetres (9.8 in) in length.

Avaceratops also had a beaked mouth, and would have fed on plants and shoots. Avaceratops was first discovered in 1981 in Montana, USA which is somewhat of a hotbed for remains of Avaceratops.

Avimimus

Matt Martyniuk, CC BY-SA 3.0, via Wikimedia Commons

Avimimus, first named in 1981 which means “bird mimic” and lived around 85 to 70 million years ago in the late Cretaceous period. Avimimus is best described as a small, bird-like dinosaur and was classed as a oviraptorosaurian theropod dinosaur. It is estimated to have been around 1.5m (5ft) in length and up to 3 ft in height.

This fascinating theropod Dinosaur had a small head, large eyes and a parrot-like beak. It is believed that Avimimus may have fed on plants, seeds as well as insects.

Avimimus also had feathers which you’d expect, however it is believed that Avimimus could not fly. Avimimus had very long and strong legs for a dinosaur its size. Scientists believe that due to the size and shape of its legs it would mean that Avimimus would have been incredibly nimble and could run very quickly.

Several nearly complete skeletons of Avimimus have been found, with the most notable specimen being found in 1996.