Tylocephale is closely related to other Asian pachycephalosaurs, like Homalocephale and Goyocephale, being part of the Old World branch of the group.

During a joint Polish-Mongolian Expedition to the Khulsan outcrop of the Barun Goyot Formation in the Gobi Desert, a large skull and mandible of a pachycephalosaur (catalogue number ZPAL MgD-I/105) was unearthed in 1971.

[1] This was one of a series of expeditions carried out between 1963 and 1971 that were spearheaded by Polish paleontologist Zofia Kielan-Jaworowska, which collected scores of well-preserved dinosaur skeletons.

The specimen was one of several dinosaur individuals discovered at Khulsan during the 1970s, with material of the ankylosaurs Tarchia and Saichania, ceratopsid Breviceratops, and theropod Hulsanpes found in the locale.

[2] The pachycephalosaur skull found at Khulsan was one of several collected during the Polish-Mongolian Expeditions, with other specimens in the nearby Nemegt Formation gathered in addition to Barun Goyot.

The pachycephalosaur material from both formations was described in scientific literature in the journal Palaeontologica Polonica in 1974 by Teresa Maryańska and Halszka Osmólska.

The genus name Tylocephale comes from the Greek words tyle ("swollen") and cephale ("head") and refers to the skull's prominent cranial dome.

All of these taxa were grouped in a new order Maryańska and Osmólska named Pachycephalosauria, which contained North American genera like Stegoceras and Pachycephalosaurus as well.

[7] No postcranial fossils belonging to Tylocephale have been found, though there are well preserved skeletons of the related Stegoceras, Homalocephale, and Prenocephale.

Based on these taxa, Tylocephale had a short neck, tiny forelimbs, long hindlimbs, and a thick, rodlike tail for balance.

This roof is also thicker and bears a peak further posteriorly than observed in other members of the group, a distinguishing feature of the taxon.

The splanchnocranium's (back part of cranium) lateral wall, jugal, and quadratojugal (cheekbone) form a transversely broad structure.

[9] Tylocephale was a member of the group Pachycephalosauria, a family of thick-skulled, herbivorous, bipedal dinosaurs which lived during the Cretaceous period in Asia and North America.

[15] Despite this, the pachycephalosaurs of Asia such as Tylocephale, Homalocephale, and Goyocephale are often recovered in a similar grade, whereas the North American Pachycephalosaurus, Stygimoloch, and Alaskacephale are in a distinct group.

[19][20] Tylocephale specifically is most closely related to the dome-headed Foraminacephale and flat-headed Homalocephale according to most recent phylogenetic analyses.

[23] Below on the left is Tylocephale's position within Pachycephalosauridae according to Schott & Evans' 2016 publication on the classification of Foraminacephale, which recovers it as more basal to a larger North American clade.

[24] On the bottom right is the phylogenetic location of Pachycephalosauria as a whole based on Dieudonné et al (2020):[12] Wannanosaurus yanshiensis Hanssuesia sternbergi Colepiocephale lambei Stegoceras validum Stegoceras novomexicanum Goyocephale lattimorei Homalocephale calathocercos Tylocephale gilmorei Foraminacephale brevis Amtocephale gobienses Prenocephale prenes Acrotholus audeti Pachycephalosaurus wyomingensis Alaskacephale gangloffi Dracorex hogwartsia Stygimoloch spinifer Sphaerotholus goodwini Sphaerotholus buchholtzae It is uncertain what pachycephalosaurs ate; having very small, ridged teeth they could not have chewed tough, fibrous plants as effectively as other dinosaurs of the same period.

It is assumed that their sharp, serrated teeth were ideally suited for a mixed diet of leaves, seeds, fruit, and insects.

Tylocephale's dome is most similar to Pachycephalosaurus' with the presence of fused sutures, tubercules on the mandible and nasal, and expanded shelves on the squamosal.

Tylocephale, Prenocephale, and Pachycephalosaurus' extra ornamentation suggest that the dome was not purely for display or species recognition, but for agonistic behaviors like head-butting.

The white-bellied duiker was found to be the closest morphological analogue to Stegoceras; this head-butting species has a dome which is smaller but similarly rounded.

[31][32] This formation is mostly characterized by a series of red beds, mostly light-coloured sands (yellowish, grey-brown, and rarely reddish) that are locally cemented.

[33][34][31] Tylocephale is endemic to the Barun Goyot Formation, which was also home to many other vertebrates, including the ankylosaurids Saichania, Tarchia and Zaraapelta;[35][36] alvarezsaurids Khulsanurus and Parvicursor;[37] birds Gobipipus, Gobipteryx and Hollanda;[38] protoceratopsids Bagaceratops and Breviceratops;[32] dromaeosaurids Kuru and Shri;[39][40] halszkaraptorine Hulsanpes;[41] and oviraptorids Conchoraptor, Heyuannia and Nemegtomaia.