Skeletal remains of Tyrannosauroidea (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

“…Although most sutures on the holotype of T. euotica are fused, part of the broken parabasisphenoid was not fused to the remainder of the braincase, perhaps suggesting that the individual was not yet osteologically mature and adults of the species may have been somewhat larger. However, almost all other tyrannosauroid specimens from the Bissekty Formation are of the same size, or smaller, than corresponding bones in the holotype of X. baimoensis (9). The one possible exception is a fragment of the posterior end of the lower jaw that was described as belonging to a fully grown adult, which cannot be directly compared with Xiongguanlong (the lower jaw of which is unknown) but is of the approximate size of the corresponding bones in subadult tyrannosaurids (16).…”

“…S4). We also refer to T. euotica a series of isolated cranial and postcranial bones described by Averianov and Sues (9) and identified as belonging to indeterminate tyrannosauroids (Fig. 1).…”

“…S5B) recovered Timurlengia and Xiongguanlong as a sister-taxon pair of intermediate-grade tyrannosauroids. Finally, we ran a third analysis in which Timurlengia was scored based on the holotypic braincase and all additional material described by Averianov and Sues (9). This produced 99,999 most parsimonious trees (length = 3,367, consistency index = 0.322, retention index = 0.777), the strict consensus of which (Fig.…”

“…S5A). We then undertook a second analysis in which Timurlengia was scored based only on the series of referred specimens described by Averianov and Sues (9). This produced 99,999 most parsimonious trees (length = 3,364, consistency index = 0.322, retention index = 0.777), the strict consensus of which (Fig.…”

“…90-92 million years ago) Bissekty Formation of Uzbekistan. This formation has recently emerged as one of the most important records of midCretaceous dinosaurs globally (9)(10)(11). Possible tyrannosauroid specimens from the Bissekty Formation were reported more than a half century ago (12), and, more recently, several isolated fossils were assigned to the group (9, 13), but none of these has been particularly complete or diagnostic at the species level, and their phylogenetic relationships have been difficult to assess.…”