Fancisco Javier Muñiz was an Argentinian paleontologist, making a number of discoveries along the Luján River.
Francisco was born in San Isidro in 1795, and enlisted as a Cadet to defend against the English invasions of Río de la Plata in 1807. He became a military doctor in 1821 during a campaign to force indigenous people off of their land, while studying their culture. In 1824, he was transferred to a fort at Chascomús, where he began to study paleontology.
Over the years, he built up a personal collection of fossils, which were donated to the leader of Argentina at the time, which were then donated again to the Muséum national d'histoire naturelle in Paris. In 1847 he published 'Apuntes Toggraficos', which discussed fossils found in different ages of sediment South of the province of Buenos Aires.
In 1871, there was an outbreak of Yellow Fever in Buenos Aires. Francisco helped treat people suffering from the disease, but ended up contracting it and died that year.
Francisco is seen as the first important Argentine naturalist, and has a hospital (Hospital Muñiz) and a museum (Museo de Historia Natural "Francisco Javier Muñiz" de Moreno) were named in his honour.