Fossil Emberizidae and Passerellidae
I'd say it would be a chocker if it is part of Emberizidae rather than Passerellidae, biogeographically! No other breeding emberizids in Americas nowadays.
Not such a big shocker, many fossil have members in places you would not expect, For example the oldest Hummingbirds are not from South or North America, they are from Europe:
Eurotrochilus inexpectatus G. Mayr, 2004 Early Oligocene of Germany;
Eurotrochilus noniewiczi Bocheński et Bocheński, 2008. Early Oligocene of Poland;
Eurotrochilus sp. Louchart, Tourment, Carrier, Roux et Mourer-Chauviré, 2007. Early Oligocene of France.
But in this case I agree with gusasp. There are some species of the Emberizidae described from Europe:
Emberiza bartkoi Kessler et Hír, 2012. Early Miocene of Hungary
Emberiza pannonica Kessler, 2013. Late Miocene of Hungary
Emberiza polgardiensis Kessler, 2013. Late Miocene of Hungary
Emberiza media Kessler, 2013. Pliocene of Hungary
Emberiza parva Kessler, 2013. Pliocene of Hungary
Emberiza gaspariki Kessler, 2013. Pliocene of Hungay
Emberiza alcoveri Rando, Lopez et Seguí, 1999. Late Pleistocene/Holocene of Tenerife
From South America we also know a species that was described in the Emberizidae, but was compared with
Zonotrichia and
Junco so it might also be a Passerellidae:
Pampaemberiza olrogi Agnolin, 2007. Middle Pleistocene of Argentina.
Free pdf's
Agnolin, 2007
Un Nuevo Emberizidae del Pleistoceno Inferior-Medio de la Provincia de Buenos Aires, Argentina
https://gredos.usal.es/jspui/bitstream/10366/79879/1/Un_nuevo_Emberizinae_(Aves,_Passeriforme.pdf
Kessler, 2013
Neogene Songbirds (Aves, Passeriformes) from Hungary
https://www.researchgate.net/publication/287410379_Neogene_songbirds_Aves_Passeriformes_from_Hungary
Kessler & Hír, 2012
The avifauna in North Hungary during the Miocene Part II
https://www.researchgate.net/public...a_in_North_Hungary_during_the_Miocene_Part_II
J. C. Rando, M. Lopez & B. Seguí, 1999
A New Species of Extinct Flightless Passerine (Emberizidae: Emberiza) from the Canary Islands
https://www.researchgate.net/public..._Emberizidae_Emberiza_from_the_Canary_Islands
Fred