Paleontology of the Caballero and Lake Valley Formations (Lower Mississippian) west of the Rio Grande, south-central New Mexico
— Barry S. Kues

The late Kinderhookian to middle Osagean Caballero–Lake Valley (CLV) sequence near Lake Valley and in neighboring areas contains a diverse marine invertebrate fauna numbering more than 200 reported species. The Nunn Member of the Lake Valley Formation, the most highly fossiliferous unit in this sequence, is best known for its well-preserved crinoid fauna, but also contains large numbers of brachiopods and corals, and lesser numbers of many other groups. A review of this fauna based on the published literature and recently made collections indicates the presence of numerous undescribed or previously unreported species. Additional study of most major elements of the fauna would be very worthwhile. Comparison of reported taxa from western and eastern (mainly Sacramento Mountains) parts of the CLV outcrop area revealed significant differences. Two-thirds of the reported taxa from these formations are apparently restricted to either the eastern or western areas, with only one-third of the species having been reported from both areas. Possible ecological (greater heterogeneity of environments associated with "Waulsortian" mound development to the east) and paleobiogeographic (proximity of western exposures to restricted connections with the Western Interior faunal province)  explanations are suggested, but incomplete knowledge of taxonomy and geographic distribution of many species is probably of equal importance. As presently known, the CLV faunas are very similar to, though less diverse than, those of the Burlington shelf (Missouri, Iowa), but apparent similarity will decrease as the CLV faunas become better studied.