Skip to main content

Why did Tyrannosaurus rex have short arms?





Skeletons of the dinosaur Tyrannosaurus rex (T-rex) show that it had short arms. Why did Tyrannosaurus rex have short arms instead of no arms or longer limbs? A carnivorous dinosaur skeleton found in South America may have the answer.

Skeleton remains of a Gualicho shinyae – a medium-sized two-legged theropod dinosaur, weighing about 1,000 pounds (450 kilograms), had forelimbs about the size of a human child’s arms – and is similar to T-rex even though they developed independently of each other.

The Gualicho shinyae is referred to as the Argentinean non-T-rex. T-rex is much larger and weighs 6,000 pounds (2,720 kilograms). The Gualicho lived about 90 million years ago during the mid-Cretaceous period, whereas T-rex lived about 60 million years ago. Therefore they did not meet each other even though they lived in the same region. T-rex is pictured above and Gualicho shinyae is pictured below (artists interpretation).



Like T-rex, the Gualicho shinyae had just digits on its hands – a thumb and a forefinger. The incomplete skeleton was discovered in 2007 during an excavation in northern Patagonia in South America.

Palaeontologists say the similarities of the two dinosaurs is an example of convergent evolution: the development of identical traits in unrelated species due to natural selection.

Therefore the small forelimbs – short arms – on a carnivorous (meat-eating) dinosaur – was there for a reason, but scientists are still unsure why. ‘By learning more about how reduced forelimbs evolved, we may be able to figure out why they evolved,’ said Dr. Peter Makovicky from The Field Museum in Chicago. He said it was an unusual feature of carnivorous dinosaurs because it is different from other carnivorous dinosaurs found in the same rock formation. The Gualicho shinyae appears to be mostly related to Deltadromeus, a leggy carnivorous dinosaur with slender arms from Africa.

The name Gualicho is the Argentinean term for ‘bad luck’ because the palaeontologists who discovered the dinosaur had an accident in which a truck carrying the skeleton over-turned (no one was hurt).




http://www.mirror.co.uk/news/world-news/tiny-arms-fearsome-rex-dinosaur-8415165




MARTINA NICOLLS is an international aid and development consultant, and the author of:- The Shortness of Life: A Mongolian Lament (2015), Liberia’s Deadest Ends (2012), Bardot’s Comet (2011), Kashmir on a Knife-Edge (2010) and The Sudan Curse (2009).
Labels:

Comments

Post a Comment

Popular posts from this blog

Pir-E-Kamil - The Perfect Mentor by Umera Ahmed: book review

The Perfect Mentor pbuh  (2011) is set in Lahore and Islamabad in Pakistan. The novel commences with Imama Mubeen in medical university. She wants to be an eye specialist. Her parents have arranged for her to marry her first cousin Asjad. Salar Sikander, her neighbour, is 18 years old with an IQ of 150+ and a photographic memory. He has long hair tied in a ponytail. He imbibes alcohol, treats women disrespectfully and is generally a “weird chap” and a rude, belligerent teenager. In the past three years he has tried to commit suicide three times. He tries again. Imama and her brother, Waseem, answer the servant’s call to help Salar. They stop the bleeding from his wrist and save his life. Imama and Asjad have been engaged for three years, because she wants to finish her studies first. Imama is really delaying her marriage to Asjad because she loves Jalal Ansar. She proposes to him and he says yes. But he knows his parents won’t agree, nor will Imama’s parents. ...
1 comment
Read more

Apes go to the movies - and remember the scenes

Apes remember major events in movies, even after a single viewing. That’s the findings of primate research in Japan (New Scientist, September 17, 2015). Researchers at the Kyoto University in Japan conducted experiments with two species of apes – chimpanzees and bonobo primates – to test their memory and recall. Instead of using food to test memory, they used films. The researchers made two short movies to show to the apes. Fumihiro Kano and his colleague, Satoshi Hirata, starred in the films with another person dressed as an ape. They wanted to have strong dramatic scenes to see if the apes remembered them. In the first 30-second movie the character ape bursts through a door on the right hand side (there is also a door on the left hand side) and attacks the two researchers (characters) 18 seconds after the start. After 24 seconds a human character choses one of two weapons next to each other and launched a revenge attack on the ape. In the second 30-second movie t...
Post a Comment
Read more

The acacia thorn trees of Kenya

There are nearly 800 species of acacia trees in the world, and most don’t have thorns. The famous "whistling thorn tree" and the Umbrella Thorn tree of Kenya are species of acacia that do have thorns, or spines. Giraffes and other herbivores normally eat thorny acacia foliage, but leave the whistling thorn alone. Usually spines are no deterrent to giraffes. Their long tongues are adapted to strip the leaves from the branches despite the thorns. The thorny acacia like dry and hot conditions. The thorns typically occur in pairs and are 5-8 centimetres (2-3 inches) long. Spines can be straight or curved depending on the species. MARTINA NICOLLS is an international aid and development consultant, and the author of:- Similar But Different in the Animal Kingdom (2017), The Shortness of Life: A Mongolian Lament (2015), Liberia’s Deadest Ends (2012), Bardot’s Comet (2011), Kashmir on a Knife-Edge (2010) and The Suda...
1 comment
Read more