Doctor Rivero obtained a Bachelor of Science in Agronomy from the University of Puerto Rico at Mayagüez in 1945. In 1942 he joined the Beta-Activo Chapter of Phi Sigma Alpha Fraternity. In 1951 he obtained an Master of Surgery from, followed by a Doctor of Philosophy from that same institution in 1953.
After obtaining his bachelor"s degree, Doctor Rivero served as an Assistant Plant Physiologist, Instructor, Assistant Professor and Associate Professor before becoming a full Professor of Biology at University of Puerto Rico-Mayagüez in 1958. Between 1966 and 1968, he served as a Research Associate at Harvard University and Visiting Scientist at the Venezuelan Institute of Scientific Investigation. In addition to founding the Mayagüez Zoo, Puerto Rico"s only zoological garden, it was named after him in 1998.
He discovered over a hundred animal species, particularly amphibians and reptiles.
In addition to writing over 200 papers and articles, he wrote numerous books, including: Los coquíes de Puerto Rico El Coquí Dorado de Puerto Rico y otras Ranas de Hábitos Reproductivos Peculiares Anfibios y Reptiles de Puerto Rico Anfibios y Reptiles de Nuestro Folklore Los Machos, las Hembras y los Intersexos Biología del Sexo Principios de Evolución Orgánica Los Helechos Cuernos de Alce o Platicerios Salientia de Venezuela Expedición de la University of Puerto Rico a las Selvas del Alto Orinoco 1950 El Dolor de la Espalda Baja He wrote the Phi Sigma Alpha "Brindis" or toast. Several species have been named to honor Doctor Rivero"s contributions to science, including: Geomelania riveroi Clench Hemitrochus riveroi Tuner (molluses) Glomiredismus riveroi Chamberlin (miriapod) Ballophilus riveroi Chamberling (miriapod) Phostherapis riveroi Danoso Barros (frog) Atractus riveroi (snake) Hyla riveroi Cochran and Going (frog) Processa riveroi Manning & Chace (crustacean) Leptodactylus riveroi Heyer (frog) Manshalkla riveroi Eleutherodactylus juanariveroi.
After founding the institution"s zoo in 1954, he served as its first director, as well as founder and director of the University of Puerto Rico"s Institute of Marine Biology. From 1959 to 1960 he served as director of the Biology Department and from 1962 to 1966, as Dean of Arts and Sciences, oversaw the work of over 200 faculty members and a two million dollar annual budget. He was the founder and first president of the Puerto Rico Zoological Society, as well as of the Association of Island Marine Laboratories.
