Ever wondered why the mighty T. Rex had such tiny arms?<\/p>\n
A British team of palaeontologists* has been studying the bones and sinew marks* of T. Rex fossils to figure out how they ticked, including why the apex predator had such puny upper arms and comically small claws.<\/p>\n
It turns out, the \u201ctyrant lizard king*\u201d wasn\u2019t only about brawn.<\/p>\n
It also had to use its considerable head.<\/p>\n
EVOLUTIONARY ARMS RACE
\u201cWhy would it have arms so short that it couldn\u2019t even reach its own mouth? How did it use them?\u201d asked Binghamton University palaeontologist and Assistant Professor Sara Sheffield in an article for media publication the Conversation.<\/p>\n
The T. Rex had arms about 30 per cent the length of its legs, she explained. If this were applied to a 1.8m (6ft) tall human, their arms would be just 30cm long.<\/p>\n
Previous theories have offered a wide range of reasons for this anatomical anomaly.<\/p>\n
Dr Sheffield was not part of the British research team, but her questions have been asked time and time again by many researchers in the field.<\/p>\n
\u201cYou can see the shortening of T. Rex\u2019s arms as a pattern in its family tree, as earlier relatives had proportionally longer arms,\u201d the tyrannosaur specialist said.<\/p>\n
Perhaps the T. Rex needed small arms to attract the attention of a mate \u2013 but mate attraction in the animal kingdom usually involves distinct differences between males and females.<\/p>\n
Or perhaps they were needed to grasp prey in a particular way, to guide the carnivore\u2019s* attack, though palaeontologists have struggled to find evidence supporting that scenario.<\/p>\n
Was it a response to accidental bites among a pack feeding frenzy? Or about redistributing weight to ensure the T. Rex could keep its balance?<\/p>\n
University College London (UCL) and University of Cambridge palaeontologists now believe T. Rex arms shrank simply because they were useless.<\/p>\n
\u201cWe sought to understand what was driving this change and found a strong relationship between short arms and large, powerfully built heads,\u201d said lead researcher, UCL palaeontologist Charlie Scherer. \u201cThe head took over from the arms as the method of attack.\u201d<\/p>\n
It was an evolutionary* way of dealing with larger, more difficult prey.<\/p>\n
Sauropods* (such as brontosaurus) got bigger. Ceratopians* (such as triceratops) expanded their horned crests. Ankylosaurus* armour grew thicker. And duck-billed hadrosaurs* were increasingly fast.<\/p>\n
Grappling arms could no longer cut it.<\/p>\n
But a high-velocity, battering-ram-like head and crushing bite could.<\/p>\n
\u201cTrying to pull and grab at a 100ft-long (30m) sauropod with your claws is not ideal,\u201d Mr Scherer said. \u201cAttacking and holding on with the jaws might have been more effective.\u201d<\/p>\n
LONG REIGN THE KING
The tyrannosaurus family, whose members became the largest known land predators*, were so successful that they lived right up until an asteroid strike killed off all the dinosaurs some 66 million years ago.<\/p>\n
We know roughly when they appeared. But how long individuals lived has been something of a mystery.<\/p>\n
New research, however, suggests it may have taken up to 40 years for a T. Rex to reach its full adult size, not the previously estimated 25 years.<\/p>\n
Analysis of 17 tyrannosaur specimens has detected previously overlooked growth rings*.<\/p>\n
\u201cUnlike the full sequence of rings visible in a tree trunk, a cross section of T. Rex bone typically captures only the final 10 to 20 years of the dinosaur\u2019s life,\u201d researchers stated in a new study published by the journal PeerJ.<\/p>\n
But by overlapping the growth rings of young T. Rex with those of older specimens, the team said they have constructed a composite* \u2013 but complete \u2013 growth curve.<\/p>\n
Biomechanics* researchers have also come up with a new theory about the way the T. Rex moved.<\/p>\n
Cinematic and silver-screen depictions of the T. Rex generally show it stomping through the forest tracking its prey.<\/p>\n
But the new study suggests it moved with catlike poise \u2013 on its toes.<\/p>\n
The researchers reached this theory by examining the monster\u2019s foot structure and the shape of preserved footprints. They then modelled how a moving foot could create such impressions.<\/p>\n
\u201c(Tests) reveal a complex and birdlike function of the foot,\u201d the study concludes.<\/p>\n
\u201cThis includes a very birdlike gait* defined by higher stride frequencies*, proportionally short stride lengths and elevated speeds.\u201d<\/p>\n
The research suggests the tyrannosaur family could run at between 18 and 40km\/hr \u2013 that\u2019s 20 per cent faster than previously thought.<\/p>\n
EVOLUTION\u2019S EMBRACE
\u201cEveryone knows the T. Rex had tiny arms, but other giant theropod* dinosaurs also evolved relatively small forelimbs,\u201d Mr Scherer said. \u201cThese adaptations often occurred in areas with gigantic prey.\u201d<\/p>\n
His team examined 82 species of theropods (two-legged, mostly carnivorous) dinosaurs and found a link between larger heads and smaller arms, with the findings published in the Royal Society Journal Proceedings B.<\/p>\n
Victory in the fight between hunter and hunted was achieved through \u201ckilling bites\u201d and dragging large prey to the ground, not by grappling and clawing them to death.<\/p>\n
\u201cThe evolutionary trend toward shorter arms in theropods \u2013 the larger group of meat-eating, two-legged dinosaurs that T. Rex belongs to \u2013 happened multiple times,\u201d said Dr Sheffield.<\/p>\n
\u201cSimilar to how wings separately evolved in different animals \u2013 like birds and bats \u2013 traits can emerge many times in evolutionary history.\u201d<\/p>\n
Tyrannosaurus Rex had the most massive, powerful skull and jaws.<\/p>\n
A close second was Tyrannotitan, which roamed the plains of Argentina 30 million years before its famous great-grandchild; it too had strangely small arms.<\/p>\n
POLL <\/p>\n
GLOSSARY<\/p>\n
palaeontologists: scientists who study fossils of plants, dinosaurs and other prehistoric organisms sinew marks: marks or grooves left on fossil bones where the soft tissue, such as tendons, ligaments and muscles, used to be attached tyrant lizard king: Tyrannosaurus rex translates to \u201cKing of the Tyrant Lizards\u201d or \u201cTyrant Lizard King, based on the Greek words tyrannos, meaning \u201ctyrant\u201d and sauros, meaning \u201clizard\u201d and the Latin word rex, meaning \u201cking\u201d carnivore: meat eater evolutionary: when species adapt to their environment over time in order to survive Sauropods: very large herbivores that walked on four legs and had very long necks Ceratopians: herbivorous, beaked dinosaurs with bony frills that often had horns, similar to rhinos. They lived 70 to 66 million years ago and were thought to roam in herds Ankylosaurus: a type of armoured dinosaur that walked on four legs and lived in the Late Cretaceous period hadrosaurs: large, duck-billed dinosaurs that walked on two legs predators: animals that hunt other animals for food growth rings: concentric bands found in fossilised bone and wood that record seasonal change and pauses in growth, helping researchers to determine the age of the animal or tree they are studying composite: made up of various parts Biomechanics: how mechanical and physical principles apply together in living beings, such as the way bones, muscles, tendons and ligaments work together to produce movement gait: style of walking stride frequencies: number of steps taken per unit of time theropod: a group of two-legged dinosaurs that were meat eaters and known for being fierce predators, such as the T. Rex <\/p>\n
EXTRA READING QUICK QUIZ LISTEN TO THIS STORY<\/p>\n CLASSROOM ACTIVITIES Then, reread the paragraph describing evolutionary changes in other dinosaurs. For each example, write a simple explanation of how that adaptation may have helped the dinosaur survive.<\/p>\n Time: allow 25 minutes to complete this activity 2. Extension Choose three different animals and create humorous sketches by giving them exaggerated or disproportionate body parts.<\/p>\n Time: allow 15 minutes to complete this activity VCOP ACTIVITY Create three new headlines for the events that took place in this article. Remember, what you write and how you write it will set the pace for the whole text, so make sure it matches.<\/p>\n Read out your headlines to a partner and discuss what the article will be about based on the headline you created. Discuss the tone and mood you set in just your few, short words. Does it do the article justice? Will it capture the audience\u2019s attention the way you hoped? Would you want to read more?<\/p>\n Consider how a headline or title is similar to using short, sharp sentences throughout your text. They can be just as important as complex ones. Go through the last text you wrote and highlight any short, sharp sentences that capture the audience.<\/p>\n","protected":false},"excerpt":{"rendered":"Ever wondered why the mighty T. Rex had such tiny arms? A British team of palaeontologists* has been…\n","protected":false},"author":2,"featured_media":691127,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[337280,315945,172136,76267,337282,337299,337288,64,63,337274,337300,73687,337287,23062,337291,337271,264704,337290,323777,337294,2618,337298,224352,337315,337272,2105,337303,337289,337308,337284,264687,337301,337295,337305,337313,337302,69071,253487,337286,337297,337292,337307,337281,337310,337311,128,337275,337304,337285,337314,337306,337270,337276,337309,337273,337296,337283,337293,39972,337312,69251,35579,337279,36795,337278,337277],"class_list":["post-691126","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-adelaide-zoo","tag-adult-size","tag-animal-kingdom","tag-apex-predator","tag-armoured-dinosaur","tag-article-justice","tag-asteroid-strike","tag-au","tag-australia","tag-battering-ram-like-head","tag-being-fierce-predators","tag-binghamton-university","tag-british-research-team","tag-british-team","tag-charlie-scherer","tag-chris-pavlich","tag-curriculum-links","tag-dino-bone","tag-dinosaur-fossils","tag-disproportionate-body-parts","tag-ethan-miller","tag-evolutionary-arms-race","tag-family-tree","tag-famous-great-grandchild","tag-fossil-bones","tag-getty-images-inc","tag-giant-theropod","tag-grappling-arms","tag-greek-words-tyrannos","tag-growth-rings","tag-kids-news-poll","tag-ligaments-work","tag-lizard-king","tag-long-extinct-creatures","tag-meat-eaters","tag-media-publication","tag-multiple-times","tag-news-story","tag-pack-feeding-frenzy","tag-reach-adulthood","tag-record-seasonal-change","tag-rex-specimens","tag-rings-visible","tag-royal-society","tag-sara-sheffield","tag-science","tag-silver-screen-depictions","tag-sinew-marks","tag-stride-frequencies","tag-stride-lengths","tag-t-rex-small-arms","tag-tiny-arms","tag-tree-trunk","tag-two-legged-dinosaurs","tag-tyrannosaur-family","tag-tyrannosaur-specialist","tag-tyrannosaur-specimens","tag-tyrannosaurus-family","tag-tyrannosaurus-rex","tag-tyrant-lizard-king","tag-university-college-london","tag-university-of-cambridge","tag-unusual-body-proportions","tag-visual-arts","tag-way-bones","tag-word-rex"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/691126","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=691126"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/691126\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/691127"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=691126"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=691126"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=691126"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
How smart was the mighty T. rex?<\/a>
Dino\u2019s dinner studied from fossils<\/a>
What to do if you find a dino bone<\/a><\/p>\n
1. How big were the T. Rex\u2019s arms compared to its legs?
2. What does the T. Rex\u2019s head have to do with the size of its arms?
3. What new theory has emerged about the way the T. rex walked?
4. At what age did a T. Rex reach adulthood, according to scientists?
5. How long ago did the T. Rex become extinct?<\/p>\n
1. Summarise and theorise
Show your understanding of this news story by writing a paragraph-long summary explaining the latest theory about why the T. Rex had unusually small arms compared to the rest of its body. Include information about how scientists believe this adaptation helped T. Rex.<\/p>\n
Curriculum Links: English; Science<\/p>\n
The T. Rex\u2019s unusual body proportions, especially its tiny arms, have often made it a funny or exaggerated character in books, movies and cartoons.<\/p>\n
Curriculum Links: English; Visual Arts<\/p>\n
Read this!
A headline on an article \u2013 or a title on your text \u2013 should capture the attention of the audience, telling them to read this now. So choosing the perfect words for a headline or title is very important.<\/p>\n