 The genus is known only from the two holotype fossils , a fruit body ( or mushroom ) and a fragment of a mushroom , both currently residing in the American Museum of Natural History . The specimens , collected in November 1994 from the area of East Brunswick , New Jersey , by G.R. Case , P.D. Borodin , and J.J. Leggett , were found as a single clear yellow amber nodule 6 cm ( 2 @.@ 4 in ) in diameter . The specimen was found above the South Amboy Fire Clay , part of the Raritan Formation , suggesting that it is Turonian in age ( Upper Cretaceous , about 90 to 94 million years ago ) . Due to weathering , the amber specimen AMNH NJ @-@ 90 fractured into a number of chips along fractures and flow lines . The chips with the holotype specimens , AMNH NJ @-@ 90Y and AMNH NJ @-@ 90Z , were first studied by a group of researchers consisting of David Hibbett and Michael Donoghue from Harvard University with David Grimaldi of the AMNH . Hibbett and colleagues published their 1997 type description in the American Journal of Botany . The generic epithet Archaeomarasmius is a combination of the Greek <unk> meaning " ancient " and " Marasmius " , a modern genus which it resembles . The specific epithet " leggetti " was coined by the authors in honor of J.J. Leggett and company , who first discovered the amber nodule and donated it to the AMNH . 
