Amateur collectors are critical to the study of fossil vertebrates: A case study from two Neogene localities in Northern California (Santa Margarita and Purisima formations)

Vertebrate paleontology was born from the efforts of amateur and commercial fossil collectors in the nineteenth century. Amateur fossil collecting is a popular hobby in the USA, though owing to different ownership laws, American vertebrate paleontologists have less positive attitudes toward amateur collectors than in Europe where amateur and professional collectors work synergistically. Collections-based and literature surveys were conducted to evaluate the scientific contribution of amateurs to vertebrate paleontology near Santa Cruz, California. The first was a survey of museum collections identifying collector status (amateur or professional) of fossils from two formations (Santa Margarita Sandstone, Purisima Formation). The second was a com-prehensive literature survey for these two stratigraphic units, documenting whether fossils were collected by amateurs or professionals. The third was a literature survey of all published (2009-2021) Cenozoic marine vertebrate records for the Pacific coast of North America (Alaska to Baja California, Mexico). The first survey indicates that amateurs have contributed the most (75.9%) to Santa Margarita Formation specimens and over a third (38.1%) of Purisima Formation specimens. These contributions are of high quality as they are included in 40% of all publications through time in the study area, and amateur-collected fossils are reported in half (49%) of all publications from the Pacific coast over the past decade. These findings indicate that amateur collectors are not only capable of collecting scientifically significant specimens, but appear to be integral to the study of Cenozoic marine vertebrates on the Pacific coast. Dismissive attitudes towards amateur collectors are clearly unwarranted. Advice for cultivating strong professional-amateur relations is provided.