Have fossils ever been found in the asphalt lakes of Trinidad and Venezuela?
Trinidad

Quote from https://www.smithsonianmag.com/travel/trinidad-and-tobago-nature-and-scientific-wonders-18329129/


  Quite an oddity sits in La Brea in South Trinidad—the world's largest asphalt lake. Pitch Lake, while perhaps not the most beautiful of nature's creations, is certainly an intriguing one. The 100-acre lake is believed to be 250 feet deep in the center and contains some 10 million tons of pitch. As the lake replenishes itself and turns over, artifacts both peculiar and historically significant such as a mastodon tooth, fossil remains of the giant sloth, and Amerindian artifacts have been uncovered. Mineral pools on the lake are purported to have healing properties because of their high sulphur content.


Venezuela

One example from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6097493/ is an article with the title


  Fossil snakes (Squamata, Serpentes) from the tar pits of Venezuela: taxonomic, palaeoenvironmental, and palaeobiogeographical implications for the North of South America during the Cenozoic/Quaternary boundary


Summary:

yes, fossils have been found