1/8/2024 0 Comments Animal age part 12![]() Tyrannosauroids Kept in Check by Carcharodontosauriansįor much of the Cretaceous allosauroids (part of the Carnosauria clade), including carcharodontosaurians were the largest terrestrial predators on Earth. The discovery of Ulughbegsaurus records the geologically latest stratigraphic co-occurrence of carcharodontosaurid and tyrannosauroid dinosaurs from Laurasia and evidence indicates carcharodontosaurians remained the dominant predators relative to tyrannosauroids, at least in Asia, as late as the Turonian faunal stage of the Cretaceous. This suggests that Timurlengia was a secondary predator along with an as yet, unnamed large dromaeosaurid, whilst Ulughbegsaurus occupied the niche of apex predator. The tyrannosauroid Timurlengia was approximately 3-4 metres long and around 8 times lighter. Ulughbegsaurus uzbekistanensis was much bigger than any other theropod known from this region. The researchers, which included corresponding author Kohei Tanaka (University of Tsukuba, Japan) and Darla Zelenitsky (University of Calgary, Canada), conclude that the individual represented by the single bone was probably 7.5 to 8 metres in length. Based on this data, the authors of this paper, calculate that the Ulughbegsaurus specimen was at least 7 metres long and over a tonne in weight. Studies of carcharodontosaurids and tyrannosaurids have demonstrated that the length of the tooth row in the maxilla is isometrically correlated with femur length, which is very helpful, as the length of the thigh bone is widely used to help calculate body mass. Palaeontologists can use the size of the tooth row in the maxilla to help them estimate the body size of theropod dinosaurs. Estimating Size from a Single Fragment of Bone The tyrannosauroid Timurlengia euotica was coeval, but much smaller than Ulughbegsaurus providing further support for the idea that carcharodontosaurians were the dominant, apex predators in Laurasia until their extinction some 20 million years prior to the end of the Cretaceous, from which point onwards it was the tyrannosauroids that took over this niche in most Laurasian ecosystems.Ī life reconstruction of Ulughbegsaurus uzbekistanensis (top) compared in size with the coeval tyrannosauroid Timurlengia euotica which was named and described in 2016. Several other predatory theropods have been described from fossils found in this formation, but all of them are considerably smaller. Ulughbegsaurus has been named based on partial maxilla found in strata associated with the Bissekty Formation of the Kyzylkum Desert (Uzbekistan). The First Late Cretaceous Carcharodontosaurian from Central Asia Reconstruction of skull in lateral view (e) – grey missing bones are based on Neovenator, modified from Naish et al. L eft maxilla of Ulughbegsaurus (fossil specimen UzSGM 11-01-02) in (a) lateral, (b) medial, (c) ventral, (d) anterior and (e) posterior views.
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