The two specimens described here were prepared differently.
Fossil specimens described here were located during surface surveys in Pakistan in 2000 and 2004.
The holotype and referred specimens described here were recovered by field crews working with the Utah Museum of Natural History and the Bureau of Land Management.
Djarthia was added to this matrix, with scorings based on the petrosal and tarsal specimens described here and on dental specimens described by Godthelp et al. [13].
All the fossil specimens described here were obtained by screen-washing of clay samples from the Tingamarra Local Fauna and subsequent microscope-assisted sorting of the concentrate.
The specimens described here were found near the top of the major flooding sequence in the early Lutetian stage of the middle Eocene, calibrated to approximately 47.5 Ma (Figure 4).
These include the T. rex specimens described here (UCMP 137538, MOR 902; MOR 1126; 1602) as well as all T. rex specimens in the CM, RSM, TMP, UCMP, and YPM collections, although in some cases, not all elements of a skeleton were accessible for study.
They have been interpreted as belonging to the anterior trunk segments (see summary in [ 19]), but their position in the specimens described here makes this unlikely.
This specimen, in particular, closely resembles the holotype Beartooth Butte telson (YPM 204946), which is far larger then either of the specimens described here, being 128 mm in width.
The majority of the specimens described here were collected from the upper 4 m section of the Winneshiek Shale which was excavated from its only outcrop near Decorah, northeastern Iowa, in 2010.
