Megaconus is an extinct genus of allotherian mammal from the Middle Jurassic Tiaojishan Formation of Inner Mongolia, China.

Megaconus is thought to have been a herbivore that lived on the ground, having a similar posture to modern-day armadillos and rock hyraxes.

[2] However, later studies cast doubt on the euharamiyidan intrepretation, instead finding it to be a basal allotherian mammal.

Megaconus has a dentition similar to those of rodents, with large incisors at the front of the jaws and broad molars in the back.

One distinguishing feature of Megaconus is a pair of enlarged premolar teeth in the lower jaw.

[1] The holotype skeleton of Megaconus was discovered in the Daohugou Beds of the Tiaojishan Formation in Inner Mongolia, China.

One idea is that haramiyidans are close relatives of Multituberculata, the most diverse group of Mesozoic mammals, and that both are part of the larger clade Allotheria.

According to this evolutionary hypothesis (phylogeny), haramiyidans fall within the crown group Mammalia — the clade originating from the most recent common ancestor of living mammals.

Below is a cladogram modified from the analysis:[1] Adelobasileus Sinoconodon Morganucodon Megazostrodon Thomasia Haramiyavia Megaconus Eleutherodon Sineleutherus Castorocauda Haldanodon Hadrocodium Australosphenida (monotremes and extinct relatives) Eutriconodonta Multituberculata Spalacotheroidea Cladotheria (marsupials, placental mammals, and extinct relatives) A 2022 study found it to be a basal allotherian instead, due to lacking apomorphies characteristic of euharamiyidans.