Gideon Mantell (1790-1852): The Dinosaur Doctor

(doesn't he look dapper ladies?)

Gideon Algernon Mantell is perhaps best remembered for discovering Iguandon, one of the first dinosaurs to be described. This week, we will look closer at this South Saxon surgeon. Most of the information is derived from the book Dinosaur Doctor: The life and work of Gideon Mantell (Critchley, 2010).

 Gideon was born on 3rd February 1790 in the town of Lewes, East Sussex. His father, Thomas, was a shoemaker and his mother was Sarah Austen. He was the fifth child of nine, his older siblings being: Sarah (who died in infancy), Thomas, Samuel and Mary, and his younger siblings: Algernon, Joshua, Jemima and Kezia. 

 Gideon had an interest in geology at a young age and spent many days of his youth collecting fossils from the nearby hills. Unfortunately, due to bizarre religious rules, Mantell, being a Methodist, was not allowed to study at any of the local grammar schools, because they were only for Anglican pupils. As a result, he was sent to a dame school (a school run by women designed to teach the absolute basics) and later was accepted into John Button's Academy for Boys where he was taught arithmetic and geography and some over subjects like rhetoric that we don't have anymore. After this, he was sent to Westbury, Wiltshire, to continue his studies with his uncle George (this is likely to be because Button was becoming a bit of a radical and started saying things like "Down with the Monarchy!!!!!" which probably didn't go down too well with the Royalist supporters in Lewes). 

When he came back from Lewes two years later, he became an apprentice to a local surgeon, James Moore. Dr. Moore was also a keen naturalist and taught Gideon everything he knew about anatomy - both of humans and animals. Sadly, while he was an apprentice, his father, Thomas, died on 11 July 1807. But, you know what they say, always look on the bright side of life, and in this case, Thomas left Gideon enough money in his will so he could go to London and receive a Diploma from the Royal College of Surgeons.

 When he again returned to Lewes he entered into a partnership with his former mentor Dr. Moore. They were both kept incredibly busy by the many epidemics of typhoid, cholera, smallpox and other fun epidemics that were ravaging the countryside at the time. He was able to make quite a tidy sum, £750 a year. Whilst he had very little free time, he did continue his fossil collecting and in 1813 he established a correspondence with the English naturalist James Sowerby. He sent Sowerby many of his specimens which Sowerby then described and published. In recognition of Mantell's help, Sowerby even named an ammonite after him: Ammonites mantelli (now called Mantelliceras mantelli).

 In 1811, fellow amateur fossil collector Mary Anning discovered the fossil of a large crocodile (later identified as an ichthyosaur). The buzz surrounding this event prompted Gideon to become more interested in fossils and it gradually started to overtake his doctor duties (much to the chagrin of his patients I'd imagine). 

 On 4 May 1816, Gideon married 20-year-old Mary Ann Woodhouse. Since you needed to be 21 to marry, they needed her mother's permission and to obtain a special licence. Which they got.

 By 1819, Gideon was collecting fossils from a quarry at Whitemans Green near Cuckfield, West Sussex. In 1820, he found some very large bones, even bigger than the ones found by Buckland (I wonder if he put them on his wall and called them his Mantell-piece, ahahahahahahahaha...ha...no?...*clears throat* Moving on). Then, two years later, his wife, Mary, found some big teeth that could not be identified. He initially sent the teeth to the French anatomist Georges Cuvier who identified them as rhinoceros teeth (according to another geologist Charles Lyell, Cuvier told him that he made the initial identification after he had come home from a late party and when he had woken up in the morning he changed his mind and thought they were something different but didn't resend a message back to England. Considering he said this years later, it's likely he was just protecting his own ego - who wants to admit they're wrong?).

 Mantell next sent the teeth to Buckland who said they were fish teeth (how the jiminny he came to that conclusion is beyond me) but Mantell was eventually able to convince the scientific community he was right about it being something new. The question now was what was it going to be called. Mantell had previously noted its similarity with iguanas and in a letter to his friend William Conybeare, he intended to name it Iguanasaurus. Conybeare, however, didn't think that was a good name because it doesn't really indicate that it is different from the iguana, and suggested the names Iguanoides and Iguanodon instead. Mantell agreed and, in 1825, described the specimens as Iguanodon (and just like Buckland, he didn't give it a species name. That was added later in 1829 by Friedrich Holl: anglicus). 

In 1833, Mantell moved to Brighton but unfortunately, his best days were behind him. His medical practice went downhill as he spent so much of his money on his collection and even transformed his house into a museum open to the public (for free). This left him in a dire financial position. In 1838, as a last act of desperation, he sold his entire collection to the British Museum (now the Natural History Museum, where they still reside) for £4,000 (after his original price of £5,000 was rejected).

He then moved to Clapham Common, London where he continued to be a doctor, except this time with no fossil collection to distract him. Sadly, things went from bad to worse for Gideon. His wife, Mary left him in 1839. Later that year, his son, Walter, moved to New Zealand. And in 1840, his beloved daughter Hannah died aged 18. Feel sorry for him? It's about to get even worse. In 1841, Gideon was involved in a carriage accident. Somehow, he fell out of his seat, got caught in the reins of the horse and was dragged along the ground . He suffered a severe spinal injury which left him bent and in constant pain. Despite this, he continued to publish papers on prehistoric reptiles. In 1844 he moved to Pimlico, London and in the following year became addicted to opium, having used it as a painkiller for his back. This proved to be his ultimate downfall as on 10 November 1852 he took an overdose of opium, passed out and sadly died. Even to the end, he was loyal to science, as in his will, he requested that his spine be removed and studied to improve future pathology. This was indeed done and for a long time belonged to his arch-rival Richard Owen (who wrote a very mean obituary accusing Mantell of lacking any scientific knowledge and merely publishing what his friends had told him in conversation and personal letters) who kept it at the headquarters of the Royal College of Surgeons where it remained until 1969 when it was destroyed to make space.

 And so ended the life of Gideon Algernon Mantell. At the time of his death, 3 of his 4 children survived him: Ellen, Walter and Reginald. But his legacy lives on with many organisms that he named including:

Iguandon, Mantell, 1825 (an Ornithopod dinosaur)

Hylaeosaurus armatus, Mantell, 1833 (an armoured dinosaur)

Regnosaurus northamptoni, Mantell, 1848 (a Stegosaur, originally identified as a giant lizard)

Pelorosaurus conybearei, Mantell, 1850, genus only (a Sauropod dinosaur that Mantell originally wanted to name Colossosaurus until he realised that that name means statue lizard in Greek, so he named it Pelorosaurus, the monster lizard instead)

"Pelorosaurus" becklessi, Mantell, 1852 (another Sauropod although a different type to the original species of Pelorosaurus so really needs a new name)

Telerpeton elginense, Mantell, 1852 (an amphibian that is now synonymised with Lepterpeton lacertinum)

And there are a number of organisms named after Mantell including:

Mantelliceras, Hyatt, 1903 (an ammonite)

Mantelliceras mantelli, Sowerby, 1814 (an ammonite)

Mantellisaurus, Paul, 2007 (an iguanodont dinosaur)

Gideonmantellia, Ruiz-Omenaca, Canudo, Cuenca-Bescos, Cruzado-Caballero, Gasca and Moreno-Azanza, 2012 (an Ornithopod dinosaur)

The next biography will be about the guy who coined the word dinosaur: Richard Owen. But next week, we'll take a look at a frequently asked question, especially from children: Which was the biggest dinosaur?

See also:
More dinosaurs
More about Richard Owen

References:

Critchley, E. (2010) Dinosaur Doctor: The life and work of Gideon Mantell, Chalford: Amberley

Buckland, OUM J13505 and the start of a "great" story

The above image is specimen number OUM J13505, currently held in the Oxford University Museum. The bone was discovered in a quarry at Stonesfield, in Oxfordshire in 1815. The British geologist William Buckland (famous for coining the term "ice age", studying fossil dung and eating exotic animals), purchased the fossils and was immediately fascinated by them. In 1818 his French geologist friend Georges Cuvier visited him and informed Buckland that the jaw belonged to a giant lizard. They were then first mentioned in print by James Parkinson (the British surgeon who famously described Parkinson's Disease) in 1822.

Buckland finally got around to describing the material (more of it had been discovered since) in 1824. Buckland named the animal Megalosaurus the "Great Lizard" and believed it was some sort of giant prehistoric lizard, much like Cuvier (Buckland, 1824). Unfortunately, Buckland did not give it a species name, the current rules for naming animals not being in place until the late 19th century. A solution to this problem was proposed by Ferdinand von Ritgen in 1826 as he named the species Megalosaurus conybeari (Named after the English geologist and marine reptile specialist William Conybeare). However, he didn't provide an adequate description nor did he designate which specimen the species represents (this being another requirement in order for a species to be accepted). Therefore his name  is regarded as being invalid. The situation was finally rectified by Gideon Mantell (of Iguanodon fame) in 1827 who gave the animal its current name of Megalosaurus bucklandii (named after Buckland himself).

In the intervening 200 years, Megalosaurus has been used as wastebasket taxon. Pretty much EVERY European Theropod from Jurassic or Cretaceous age rocks has been regarded as a species of Megalosaurus at some point or another. This continued up until the 1980s, when palaeontologists came to the conclusion that European theropods were more diverse than just a single genus. Most of the extra species have since been reclassified but there are still hangers-on, and seeing as how they based on teeth (and in some cases just fragments of bone), it's unlikely they will ever receive much attention. There's also a funny story involving an alleged giant's scrotum, but I'll save that for another day as well a bit more information on how and where fossils are discovered. Next week will be our first biography: that of the Sussex geologist Gideon Mantell!!!

See also:
More dinosaurs
More about Gideon Mantell

References
Buckland, W. (1824) 'XXI. - Notice on the Megalosaurus or great Fossil Lizard of Stonesfield', Transactions of the Geological Society of London, 2 (1), pp. 390-396, doi: 10.1144/transgslb.1.2.390

Mantell, G. (1827) Illustrations of the geology of Sussex, London: Lupton Relfe

Parkinson, J. (1822) Outlines of Oryctology: An introduction to the study of fossil organic remains, especially those found in the British strata, London

von Ritgen, F. (1826) 'Versuchte Herstellung einiger Becken urweltlichter Thiere', Nova Acta Academiae Caesareae Leopoldino-Carolinae Germanicae Naturae Curiosorum 113, pp. 331-358

Comparative Anatomy - Are all Dinosaurs the same?

A lot of people when they hear the word dinosaur think of some giant, reptilian monster. However, dinosaurs were more varied than that and for this week, I want to compare three different genera: Compsognathus, Diplodocus and Allosaurus.

  

In order to do this, we'll look at their anatomy starting at the skull and finishing at the tail.

First the skulls. Compsognathus has a small but long and pointed skull with over 60 sharp, curved teeth. Diplodocus has a tiny head which is held at an angle. The jaws are weak with thin peg-like teeth. Allosaurus has huge jaws and a wide, hinged mouth with 70 dagger-like teeth. The massive, powerful head is held almost upright.

Next the necks. Compsognathus has a flexible neck that allows for quick movements. Diplodocus has a long, powerful neck. There is much dispute regarding sauropod necks. Were they held stiff and upright like a Giraffe's or were they flexible and low to the ground like a Swan's? Allosaurus had a thick, short and flexible neck that was built for power not agility.

Now the backbone. Compsognathus had pretty average vertebrae, nothing too exciting. Diplodocus' vertebrae were strengthened to prevent the massive body from collapsing under its own weight. Allosaurus had strong back muscles to support its body.

Next we journey to the forelimbs. In Compsognathus we see three clawed fingers, good for grasping prey (up until 2000 it was believed to only have two fingers). Diplodocus had five toes, the first being large and sharp and the others were padded like an elephant's (although this is disputed). Allosaurus has short, sturdy arms with three-fingered hands for grabbing and tearing.

Following that it is logical to look at the hindlimbs. Compsognathus had long, light-boned back legs for speed. Diplodocus had four pillar-like legs to support its weight. Allosaurus had three sharply clawed toes pointing forwards, a fourth toe pointing backwards to spread the weight and a reduced fifth toe.

Finally, we reach the tail. Compsognathus has a long tail, almost half the length of the body for balance. Diplodocus has a long, heavy tail to act as a counterbalance so it doesn't topple onto its face. This tail is also thin at the end and was probably used like a whip. Allosaurus' tail was long and muscular and was also used for balance.

And that's it. This was just meant to highlight the main body plans of dinosaurs. Part 2 (because no topic is ever finished) will look at another three body plans. Next week we will look more closely at perhaps the most important dinosaur fossil ever - OUM J13505.

See also:
More dinosaurs
More dinosaurian anatomy goodness
Skulls

Jurassic Park Part 1 - Can Dinosaurs be cloned?

As I'm sure you are aware, my favourite film is Jurassic Park (I've probably mentioned it ad nauseum - this is the last time I mention it (promise)). At the time, the idea of cloning dinosaurs to bring them back was pure fantasy, something that the scientific community were quick to point out. But, 20 years on, is it still fantasy or is there some truth to it? Let's find out!

 First of all what is cloning? According to wikipedia, cloning is the process of producing similar (this is an important word) populations of genetically identical individuals. The predominant method used is known as Somatic Cell Nuclear Transfer (or SCNT for short). This involves transferring the nucleus of an adult cell (known as a somatic cell) to an egg cell that has no nucleus. 

 In this picture of an animal cell, the nucleus is the big blue sphere. This is where the DNA is kept in Eukaryotes (animals, plants, fungi and some other funky things like algae and amoebae). 

 Once the nucleus has been transferred into the egg cell, it is then observed. If the cell starts to divide normally, the cell is placed into the uterus of a donor mother. It is at this early stage the clone ceases to be exactly identical to the original because every time a cell divides, there is a chance the DNA can mutate. Also, only the nuclear DNA is transferred. There is also DNA in the mitochondria (singular, mitochondrion, the pinky capsules with wavy things in them in the above picture). The clone's mitochondrial DNA is obtained from the surrogate mother, again ensuring that the clone will not be exactly the same as the original. The mitochondrial DNA is used to determine which proteins an organism can obtain energy from in the form of food. As a result, they are very important.

 So this raises a few questions regarding dinosaur cloning. Has dinosaur DNA been recovered and what would we use as the surrogate mother?

 Let's look at the first question. Has Dinosaur DNA ever been recovered. The answer to that is no. There has been DNA recovered from blood-sucking insects from the dinosaur times, but it's only a few strands - impossible to know whether it's from a dinosaur, pterosaur, or even the insect itself. Besides, we would need a whole genome to be able to clone a dinosaur. However, dinosaur DNA from bones has been reported but it is extremely controversial. It all started in 1994 when three American palaeontologists, Scott Woodward, Nathan Weyand and Mark Bunnell, claimed to have found the DNA in bone fragments from the Blackhawk Formation in Utah. Woodward et al. did not identify which dinosaur the fragments came from (they weren't even able to prove they were dinosaur bones anyway and the pictures used in the paper are very bad quality). But the claim was there. 80 million-year-old DNA. The following year, S. Blair Hedges and Mary Schweitzer published a rebuttal, in which they were able to show that the "ancient DNA" was in fact human DNA that had contaminated the bone (maybe someone cut themselves while handling the bones?).
 However, later that same year, a group of Chinese scientists again made the claim of discovered DNA from dinosaur egg shells. Unfortunately, they published their findings in an obscure Chinese journal which no-one read and so it escaped the scientific community (An, et al., 2005, cited in Wang, et al., 1997). That was until 1997 when another group of Chinese scientists tested the DNA and, just like Hedges and Schweitzer, found the DNA to be contaminated - this time with plant and fungi DNA (Wang, Yan and Jin, 1997).
 And that's it. They're the only claims of Dino DNA I know of. It seems to have been a very 90s phenomenon. I suppose the discovery of all those dino-birds in the early 00s seems to have distracted the scientific community.

 The second question is a bit easier and at the same time harder to answer. The ideal surrogate mother would be another dinosaur but as they're largely extinct that could be a bit difficult. However, birds would be a good alternative. Unfortunately, the only way to know is to try it and since it would be impractical and unethical at the moment, we're probably never going to know.

 So, in conclusion, while cloning a dinosaur would not be impossible in theory, the lack of any genuine dinosaur DNA and knowledge of the biochemistry of dinosaurs prevents us from being able to achieve it. In part 2, I will look at another issue of Jurassic Park that gets a lot of nerds angry on the internet. The raptors. For next week's exciting outing, we'll be looking at the functional morphology of three different dinosaurs.

See also
More dinosaurs
More Jurassic Park

References
Hedges, S. B. and Schweitzer, M. H., (1995) 'Detecting Dinosaur DNA' Science, 268 (5214) pp. 1191-1192, doi: 10.1126/science.7761839

Wang, H-L., Yan, Z-Y. and Jin, D-Y. (1997) 'Reanalysis of Published DNA Sequence Amplified from Cretaceous Dinosaur Egg Fossil', Molecular Biology and Evolution, 14 (5), pp. 589-591

Woodward, S. R., Weyand, N. J. and Bunnell, M. (1994) 'DNA Sequence from Cretaceous Period Bone Fragments', Science, 266 (5188), pp. 1229-1232

Geochronology

This is going to be a simple post for this week. Just an outline of the time periods, their names, ages and subdivisions. I hope to expand on this later but this will serve as an initial reference guide. All information is taken from the GeoWhen Database.

MYA = Million Years Ago, TYA = Thousand Years Ago

4567 MYA - Hadean
3800 MYA - Archean - Eoarchean
3600 MYA -               - Paleoarchean
3200 MYA -               - Mesoarchean
2800 MYA -               - Neoarchean
2500 MYA - Proterozoic - Paleoproterozoic - Siderian
2300 MYA -                    -                            - Rhyacian
2050 MYA -                    -                            - Orosirian
1800 MYA -                    -                            - Statherian
1600 MYA -                    - Mesoproterozoic - Calymmian
1400 MYA -                    -                            - Ectasian
1200 MYA -                    -                            - Stenian
1000 MYA -                    - Neoproterozoic - Tonian
 850 MYA -                     -                          - Cryogenian
 630 MYA -                     -                          - Ediacaran
 542 MYA - Phanerozoic - Paleozoic - Cambrian - Early Cambrian
 513 MYA -                     -                -                - Middle Cambrian
 501 MYA -                     -                -                - Late Cambrian
 488 MYA -                     -                - Ordovician - Early Ordovician - Tremadocian
 478 MYA -                     -                -                   -                           - Arenig
 471 MYA -                     -                -                   - Middle Ordovician - Ordovician III (No official name)
 468 MYA -                     -                -                   -                               - Darriwilian
 460 MYA -                     -                -                   - Late Ordovician - Ordovician V (No official name)
 455 MYA -                     -                -                   -                           - Ordovician VI (No official name)
 445 MYA -                     -                -                   -                           - Hirnantian
 443 MYA -                     -                - Silurian - Early Silurian - Llandovery - Rhuddanian
 439 MYA -                     -                -             -                      -                   - Aeronian
 436 MYA -                     -                -             -                      -                   - Telychian
 428 MYA -                     -                -             -                      - Wenlock - Sheinwoodian
 426 MYA -                     -                -             -                      -                - Homerian
 422 MYA -                     -                -             - Late Silurian - Ludlow - Gorstian
 421 MYA -                     -                -             -                     -              - Ludfordian
 418 MYA -                     -                -             -                     - Pridoli
 416 MYA -                     -                - Devonian - Early Devonian - Lochkovian
 411 MYA -                     -                -                -                         - Praghian
 407 MYA -                     -                -                -                         - Emsian
 397 MYA -                     -                -                - Middle Devonian - Eifelian
 391 MYA -                     -                -                -                            - Givetian
 385 MYA -                     -                -                - Late Devonian - Frasnian
 374 MYA -                     -                -                -                        - Famennian
 359 MYA -                     -                - Carboniferous - Mississipian - Early Mississipian
 345 MYA -                     -                -                        -                    - Middle Mississipian
 326 MYA -                     -                -                        -                    - Late Mississipian
 318 MYA -                     -                -                        - Pennsylvanian - Early Pennsylvanian
 311 MYA -                     -                -                        -                       - Middle Pennsylvanian
 306 MYA -                     -                -                        -                       - Late Pennsylvanian - Kasimovian
 303 MYA -                     -                -                        -                       -                               - Gzhelian
 299 MYA -                     -                - Permian - Early Permian - Asselian
 294 MYA -                     -                -              -                       - Sakmarian
 284 MYA -                     -                -              -                       - Artinskian
 275 MYA -                     -                -              -                       - Kungurian
 270 MYA -                     -                -              - Middle Permian - Roadian
 268 MYA -                     -                -              -                          - Wordian
 265 MYA -                     -                -              -                          - Capitanian
 260 MYA -                     -                -              - Late Permian - Wuchiapingian
 253 MYA -                     -                -              -                      - Changhsingian
 251 MYA -                     - Mesozoic - Triassic - Early Triassic - Induan
 249 MYA -                     -                 -             -                       - Olenekian
 245 MYA -                     -                 -             - Middle Triassic - Anisian
 237 MYA -                     -                 -             -                         - Ladinian
 228 MYA -                     -                 -             - Late Triassic - Carnian
 216 MYA -                     -                 -             -                     - Norian
 203 MYA -                     -                 -             -                     - Rhaetian
 199 MYA -                     -                 - Jurassic - Early Jurrasic - Hettangian
 196 MYA -                     -                 -              -                      - Sinemurian
 189 MYA -                     -                 -              -                      - Pliensbachian
 183 MYA -                     -                 -              -                      - Toarcian
 175 MYA -                     -                 -              - Middle Jurassic - Aalenian
 171 MYA -                     -                 -              -                          - Bajocian
 167 MYA -                     -                 -              -                          - Bathonian
 164 MYA -                     -                 -              -                          - Callovian
 161 MYA -                     -                 -              - Late Jurassic - Oxfordian
 155 MYA -                     -                 -              -                      - Kimmeridgian
 150 MYA -                     -                 -              -                      - Tithonian
 145 MYA -                     -                 - Cretaceous - Early Cretaceous - Berriasian
 140 MYA -                     -                 -                   -                            - Valanginian
 136 MYA -                     -                 -                   -                            - Hauterivian
 130 MYA -                     -                 -                   -                            - Barremian
 125 MYA -                     -                 -                   -                            - Aptian
 112 MYA -                     -                 -                   -                            - Albian
   99 MYA -                     -                 -                   - Late Cretaceous - Cenomanian
   93 MYA -                     -                 -                   -                           - Turonian
   89 MYA -                     -                 -                   -                           - Coniacian
   85 MYA -                     -                 -                   -                           - Santonian
   83 MYA -                     -                 -                   -                           - Campanian
   70 MYA -                     -                 -                   -                           - Maastrichtian
   65 MYA -                     - Cenozoic - Paleogene - Paleocene - Early Paleocene
   61 MYA -                     -                -                  -                 - Middle Paleocene
   58 MYA -                     -                -                  -                 - Late Paleocene
   55 MYA -                     -                -                  - Eocene - Early Eocene
   48 MYA -                     -                -                  -             - Middle Eocene - Lutetian
   40 MYA -                     -                -                  -             -                         - Bartonian
   37 MYA -                     -                -                  -             - Late Eocene
   33 MYA -                     -                -                  - Oligocene - Early Oligocene
   28 MYA -                     -                -                  -                 - Late Oligocene
   23 MYA -                     -                - Neogene - Miocene - Early Miocene - Aquitanian
   20 MYA -                     -                -                -               -                        - Burdigalian
   15 MYA -                     -                -                -               - Middle Miocene - Langhian
   13 MYA -                     -                -                -               -                           - Serravallian
   11 MYA -                     -                -                -               - Late Miocene - Tortonian
     7 MYA -                     -                -                -               -                       - Messinian
     5 MYA -                     -                -                - Pliocene - Early Pliocene
     3 MYA -                     -                -                -               - Late Pliocene - Piacenzian
     2 MYA -                     -                -                -               -                       - Gelasian
     1 MYA -                     -                -                - Pleistocene - Early Pleistocene
  781 TYA -                     -                -                -                   - Middle Pleistocene
  126 TYA -                     -                -                -                   - Late Pleistocene
    11 TYA -                     -                -                - Holocene

That's it. Hopefully, it will serve its purpose well. My next blog post on time periods will cover the Story of Life from the start to the Arrival of the Dinosaurs in the Late Triassic. But that won't be for a while yet. Next week will be an in-depth look into the movie that shaped my life, Jurassic Park. How much of it is science-fact and how much is science-fiction? Tune in next week to find out.

See also:
More dinosaurs
Life before the dinosaurs
Age of the Dinosaurs

Tyrannosaurus rex - King of the Tyrant Lizards Part 1

The year is 1993. I am a little 3-year-old terror. My little sister had only just been born and my parents needed to get rid of me for a few hours. Their plan? To take me to see a silly dinosaur movie called "Jurassic Park". The result? A life-long fascination with dinosaurs and an introduction to my favourite dinosaur - Tyrannosaurus rex. It's probably THE most famous dinosaur - along with Triceratops, Stegosaurus and Brontosaurus (although the latter is no longer valid, people still call Sauropods "Brontosaurs").

 Tyrannosaurus rex was described in 1905 by the American palaeontologist Henry Fairfield Osborn. Osborn noted that it was the largest carnivorous dinosaur that had been described up to that point (Osborn, 1905). The fossil itself was discovered in 1902 by Barnum Brown and Richard Lull from Montana. The most distinctive characteristic of Tyrannosaurus, according to Osborn, was a very large humerus, however, he does not go into any detail, because not all of the skeleton was accessible to him. However, a year later, Osborn provided a more thorough description and a longer list of characters.

Restoration from Osborn (1905)

Firstly, the skull is short, with two large openings in front of the eyes (called antorbital fenestrae) and the bone at the back of the skull (the squamosal) has a horizontal bar facing forwards. It has 13 teeth in the maxillaries (upper jaw bone) and 12-13 teeth in the dentary (the main lower jaw bone). There is a pair of reduced cutting teeth at the front of the dentary. The teeth are oval in cross-section, being wider from left-to-right than front-to-back and have serrated edges. The tooth sockets (called dental alveoli) are expanded into triangular supporting plates on the inner side of the jaws.

 Tyrannosaurus skull from Osborn (1906) The dotted lines indicate missing material and were based on the skull of Allosaurus, a rather different Theropod.

In terms of the vertebrae (backbones), Osborn was unsure of the number of presacral vertebrae (the backbones in front of the hip) but he guessed 23. It had nine cervical vertebrae (neck bones) with broad neural spines (the part of the vertebra that sticks up) and 5 sacral (hip) vertebrae with the spines fused together to form one continuous ridge. The atlas (first cervical vertebra) is composed of four parts: the hypocentrum (a horseshoe-shaped mass of bone on the underside), two neurapophyses (a pair of arches at the top) and a pleurocentrum or odontoid (a protuberance on the top). The axis, the second cervical vertebra, also consists of a hypocentrum as well as a centrum (which is more of a club-shaped structure).

 Tyrannosaurus cervical vertebrae

 Tyrannosaurus sacral vertebrae

The shoulder girdle has a greatly reduced scapula (shoulder blade) and humerus (upper arm bone). The large humerus Osborn was talking about in 1905 appears to be an error.

 A=Allosaurus scapula, B=Tyrannosaurus scapula

 Tyrannosaurus humerus in A=front view, B=rear view

 Tyrannosaurus also possessed abdominal ribs, unusual for Dinosaurs, which Osborn likened to the Tuatara Hatteria (now a synonym of Sphenodon). 

 Tyrannosaurus abdominal ribs

The pelvic girdle (hip) consists of an elongate and compressed ilium (Il.) with an elongate horizontal plate extending from the anterior (front) portion. The pubes (P.) are firmly fused in the middle and also at the far end. Finally, the ischia (Is.) are reduced at their ends.

 Tyrannosaurus pelvic girdle

All the limb and main girdle bones are hollow. The hind limbs are greatly elongated (Osborn appears to love that word based on how often he used it), with large, hollow cavities. The femur (thigh bone) is longer than the tibia (shin). Three of the main metatarsals (foot bones) are partly fused and the hallux (toe) is reduced.

 And that's the description of Tyrannosaurus according to Osborn (1906). More has been discovered and the description has changed since then, so let's look at the current diagnosis from the second edition of The Dinosauria (THE authority for dinosaurs). The relevant chapter on Tyrannosauroids is authored by Thomas Holtz, an expert on Theropods. Tyrannosaurus is the last and also the largest known Tyrannosaurid with a skull length of 1.53m (5ft) and a femur length of 1.38m (4ft 6in) (Holtz, 2004). In addition to this, Tyrannosaurus had the narrowest nostrils and the widest skull of any known Tyrannosaur.

And that's it. That's the description and anatomy of Tyrannosaurus done. Part 2 will look at its systematics. But that won't be for a while yet. Next will be a brief discussion on geochronology.

See also:

More dinosaurs

More Tyrannosaurus rex

References
Holtz, T. R. (2004) 'Tyrannosauroidea' in Weishampel, D. B., Dodson, D. and Osmólkska, H. (eds), The Dinosauria (2nd Edition), pp. 111-136, London: University of California Press

Osborn, H. F. (1905) 'Tyrannosaurus and other Cretaceous carnivorous dinosaurs', Bulletin of the American Museum of Natural History, 21, pp.249-265 Click to access paper

Osborn, H. F. (1906) 'Tyrannosaurus, Upper Cretaceous carnivorous dinosaur. (Second communication.)', Bulletin of the American Museum of Natural History, 22, pp.281-296 Click to access paper

What is a dinosaur?

For my first blog post, I thought I'd address a pet peeve of mine. As anyone who knows me will be fully aware of, I have a passion (and some would say obsession) with dinosaurs. As a 23-year-old (at time of writing) some might think I would have grown out of such a childish pursuit and developed an interest in more "mature" hobbies like cars, sports, or girls. And whilst an interest in one of those three has materialised, dinosaurs will always be with me. But enough about me, let's start talking about about those "terrible lizards"! (or "fearfully great" - more on the etymology at a later date)

 Nothing gets on my nerves more than someone labelling any and all prehistoric reptiles (and sometimes amphibians and even fish) as dinosaurs. There is a certain geological and map shop (or was - it's now closed down) that I pass quite regularly, that for a long time had a sign in the window that read: "For Sale: Dinosaur Teeth (Mosasaur) 100 Million Years Old". Now, average Joe Bloggs reading this is probably thinking: "What's so wrong with that?". The problem is, mosasaurs were NOT dinosaurs. And this blog post is going to attempt to show that by demonstrating what is a dinosaur and why.

 Before I get to the crux of this discussion, I feel obliged to give you a crash-course in cladistics. Cladistics is the science of classification that groups organisms together based on the degree of "relatedness" (this is slightly different to taxonomy - more on that some other time). Anyway, there are three ways to define a clade (group). Node-based, stem-based and apomorphy-based.



Node-based definitions are along the lines of : A + B, their most recent common ancestor and all of its descendants. For example Dinosauria can be defined as "Passer (sparrow) + Triceratops, their most recent common ancestor and all of its descendants". So basically, a dinosaur is any organism that branched off the line leading to Triceratops after the branch that ultimately leads to Passer. Naturally, node-based definitions are less reliable because it relies on being quite confident about which groups are the most "primitive" and which are the most "advanced".
 Stem-based definitions are similar, but more easy to understand. They are in the form of: Everything closer to A + B than to Z, to use these diagrams. So, for instance, a stem-based definition of Dinosaur would be: all Dinosauriformes (the next rank up from dinosaur) closer to Tyrannosaurus and Triceratops than to Lagerpeton (a potential dinosaur ancestor, however, this definition dates from 2004 and since then other, more dinosaur-like animals have been discovered like Silesaurus - add this to the long list of topics to cover in the future).
 Finally, apomorphy-based definitions are the ones that are most easily understood by the layperson, but don't always reflect true, natural groups. Apomorphies are characteristics that are unique to a particular group (or rather a unique combination of features). It is this definition that I wish to further explore here.

 OK, now that that's out of the way we can get to the fun stuff! First of all, there is no simple way of identifying a dinosaur. However, a few generalisations can be made. Firstly, they could not fly (sort of - the origin of flight in the whole dinosaur-into-bird thing hasn't been pinned down yet, but it seems likely that true flight evolved with the birds). This means that the pterosaurs (not pterodactlys - more on that some other time) are not dinosaurs. And yes, technically speaking, birds are dinosaurs, but just for the sake of convenience, I'm only going to be discussing traditional, non-avian dinosaurs. Secondly, dinosaurs were not fully aquatic (some evidence suggests that duck-billed dinosaurs were partly aquatic and it is presumed dinosaurs could swim). Therefore, plesiosaurs and ichthyosaurs were not dinosaurs either (and the next time I hear someone call the Loch Ness monster a dinosaur I will scream).

 According to Michael J. Benton (2004), the unique characteristics of Dinosauria are:

1. Loss of the prefrontal
2. An elongate deltopectoral crest on the humerus
3. A brevis shelf on the ventral surface of the postacetabular part of the ilium
4. An extensively perforated acetabulum
5. A tibia with a transversely expanded subrectangular distal end, as well as as caudolateral flange, a depression for the astragalus, and an ascending astragalar process on the cranial face

"What the Jiminy Cricket does that mean?!?!" I hear you cry. Well, I'm glad you asked Sunny Jim, because I'm going to explain all.

1. Loss of the prefrontal

The prefrontal is a bone in the skull just in front of the frontal (hence the name). Most dinosaurs, technically, did have a prefrontal, however, it was mostly fused to another bone, the lacrimal. Their descendants, the birds, have lost this bone completely. In the picture below, of Dromaeosaurus, the prefrontal is the lime green bone just in front of the eye, above the lacrimal. Notice how small it is.

In this picture of a python, however, the Prefrontal is labelled as C. It is a much larger bone in other reptiles.

2. An elongate deltopectoral crest on the humerus

All this means is that dinosaurs have a long crest or ridge running along the top bit of the thigh. 

Compared to other reptiles, in this case Drepanosaurus (a prehistoric tree-climbing reptile that has defied every attempt to classify it), you can see the humerus marked Hu and in light green. (Sorry about the quality, it was the only picture of a non-dinosaurian reptile humerus I could find).

3. A brevis shelf on the ventral surface of postacetabular part of the ilium

This means that, like the humerus, dinosaurs have a ridge on the bottom of the ilium (one of the hip bones), behind the acetabulum (the hip socket). On this diagram, the brevis shelf is marked bs.

Compared to this drawing of a crocodile's pelvis, the ilium (marked Il.) is much smoother and curved.

4. An extensively perforated acetabulum

What this means, simply, is that dinosaurs' hip sockets are actually holes rather than sockets.

If you look at the crocodile hip image above, you'll notice that while there is a hole (the acetabular foramen) there is still a large furrow or socket where the femur connects to the hip.

5. A tibia with a transversely expanded subrectangular distal end, as well as as caudolateral flange, a depression for the astragalus, and an ascending astragalar process on the cranial face

Let's have a look at a dinosaur's tibia, shall we?

 It has a transversely expanded subrectangular distal end (which means the bottom part is stretched and is vaguely rectangle shaped), it has a caudolateral flange (which is a small ridge running along the bottom - not easy to see in this picture), a depression for the astragalus (which means it has a furrow at the bottom allowing the bone below (the astragalus) to connect to) and an ascending astragalar process on the cranial face which can be seen better in the image below - it's the part that looks like a triangle)

So that's that. If the fossil you are looking at exhibits all of these features then it is a dinosaur. For now. It hasn't always been like this. About 15-20 years ago, there were a lot of features in the ankle that were considered to be important. But now that we've found more crocodile ancestors, it seems that dinosaur ankles weren't that unique. Maybe in 10 years time, the definition will have changed but this will suffice for now.

I hope this has explained what a dinosaur is. In future, I hope to expand upon this, with more anatomy and with other groups. What's next? An article on my favourite dinosaur: Tyrannosaurus rex!

See also:
Other dinosaur posts
More dinosaur anatomy
More on dinosaur skulls

References

Benton, M. J. (2004) 'Origin and Relationships of Dinosauria', in, Weishampel, D. B., Dodson, P. and Osmólska, H. (eds) The Dinosauria (2nd Edition), London: University of California Press