Paleonews

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2008-10-24 – Gli Eterodontosauri e l’origine dell’erbivoria nei Dinosauri Ornitischi (Heterodontosaurs and the origin of erbivory in ornitischian dinosaurs)

La scoperta di un cranio di un giovane esemplare di Heterodontosaurus favorisce nuove considerazioni sulla dieta e sul percorso evolutivo di questo dinosauro.

Prima della scoperta, la presenza di una dentatura eteromorfa (e in particolare la presenza dei canini) aveva dato luogo a due considerazioni contrastanti; alcuni ritenevano che tale dentatura costituisse una prova di un alimentazione onnivora, altri invece che la presenza dei canini fosse propria soltanto dei maschi e rappresentasse quindi solo un carattere sessuale secondario (vedi l’esempio attuale dei Trichechi)

Ora la scoperta di un esemplare giovane con canini già ben sviluppati avvalora la tesi dell’onnivoria e pone il genere Hterodontosaurus coma una delle fasi di passaggio tra un antenato carnivoro e i successori ornitischi (triceratopi, adrosauri, anchilosauri) erbivori.

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One of world’s smallest dinosaurs ever discovered ate meat AND plants

By Daily Mail Reporter
Last updated at 10:33 AM on 24th October 2008

[Photo: Laura Porro with her amazing find. The skull of a Heterodontosaurus had lain in a drawer since the 1960s]

One of the world’s smallest dinosaur skulls has been discovered, which could help explain how plant eaters branched off from their carnivorous cousins.

The tiny skull belongs to a young Heterodontosaurus, which lived 190million years ago, according to British and U.S researchers.

The mini dinosaur, which weighed around the same as an MP3 players, had fang-like canine teeth at the front for biting and tearing and flat grinding teeth typical of herbivores at the back.

‘Since Heterodontosaurs are among the earliest dinosaurs adapted to eating plants, they may represent a transition phase between meat-eating ancestors and more sophisticated, fully herbivorous descendants,’ Laura Porro from the University of Chicago said.

 ‘This juvenile skull indicates that these dinosaurs were still in the midst of that transition.’

 Porro came across the skull in a drawer in the Iziko South African Museum in Cape Town, while researching the eating habits of the Heterodontosaurs. ‘

‘I didn’t recognise it as a dinosaur at first,’ she said.

‘But when I turned it over and saw the eye looking straight at me, I knew exactly what it was.’

Although dug up in the 1960s it was never identified. The dinosaur lived during the Early Jurassic period of South Africa. Porro’s find was reported in the Journal of Vertebrate Paleontology.

 

Enlarge   dino

[Photo: The adult creatures were the size of turkeys but youngsters were half the size and only weighed half a pound, say researchers]

The first dinosaurs appeared about 230 million years ago, and the earliest known ones were meat eaters.

 There were other plant-eating dinosaurs at the time of Heterodontosaurus including the long-necked sauropods. But this little creature was one of the earliest of the ornithischians that soon become very important in the Age of Dinosaurs.

 Later ornithischians included the duck-billed dinosaurs, horned dinosaurs such as Triceratops and tank-like dinosaurs such as Ankylosaurus.

 While adult Heterodontosaurus were turkey-sized creatures that reached just over three feet in length and weighed about five pounds (2.5 kg), the juvenile likely weighed less than half a pound and would have been just about a foot and a half long.

Enlarge   skull

[Photo: The rare juvenile skull of a 190 million-year-old dinosaur may help explain when an important group of plant eaters branched off from their carnivorous cousins]

 The find also offers a rare chance to compare a young dinosaur to adults in the species. Porro said the eyes in the juvenile skull are much bigger, and the nose is much shorter.

 ‘It’s the same things that makes puppies and kittens appealing,” she said. “I think it’s adorable.’

source: http://www.dailymail.co.uk/sciencetech/article-1080194/One-worlds-smallest-dinosaurs-discovered-ate-meat-AND-plants.html

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Other links:

Tiny Juvenile Dinosaur Fossil Sheds Light On Evolution Of Plant Eaters
Science Daily (press release) – 6 ore fa
ScienceDaily (Oct. 23, 2008) — One of the smallest dinosaur skulls ever discovered has been identified and described by a team of scientists from London,
Tiny dinosaur on verge of swearing off meat
Reuters UK – 10 ore fa
By Julie Steenhuysen CHICAGO (Reuters) – A rare juvenile skull of a 190 million-year-old dinosaur may help explain when an important group of plant eaters
Dinosaur ‘was turning vegetarian’
The Press Association – 10 ore fa
One of the smallest dinosaur skulls ever discovered belonged to a creature in the process of turning vegetarian, say scientists.
One of world’s smallest dinosaurs discovered that ate meat AND plants
Daily Mail – 1 ora fa
By Daily Mail Reporter Laura Porro with her amazing find. The skull of a Heterodontosaurus had lain in a drawer since the 1960s One of the world’s smallest
Tiny Skull Sheds Light on Strange Dinosaur Diets
LiveScience.com – 9 ore fa
By Jeanna Bryner, Senior Writer Juveniles of Heterodontosaurs (the little ones in the illustration) already sported fang-like canines, and so like the

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Original article:

Journal of Vertebrate Paleontology (the link will be inserted when available) (Bioone)

ottobre 24, 2008 - Posted by | - Ornitopodi, - R. Dinosauri, Africa, Articolo sc. di riferimento, Bl - Top posts, Italiano (riassunto), Lang. - Italiano, P - Evoluzione, P - morfologia funzionale, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , , , , , ,

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