It is dated to c. 116 or 117 million years ago, in the middle of the Aptian stage of the geological time scale, and has sometimes been termed the mid-Aptian extinction event as a result.
The Aptian event is most readily detected among marine rather than terrestrial fossil deposits.
"[1] The Aptian event may have been causally connected with the Rahjamal Traps volcanism episode in the Bengal region of India, associated with the Kerguelen hotspot of volcanic activity.
[2] (At the time in question, c. 116–117 Ma, India was located in the southern Indian Ocean; plate tectonics had not yet moved the Indian landmass into its present position.)
The tritylodonts, the last surviving relatives (but not members) of the mammals went extinct around this time too.