Premise of the study: The fossil leaf Karatophyllum bromelioides L. D. Gómez found in Costa Rica was proposed by Gómez (1972) to belong to the Bromeliaceae and to date from the middle Tertiary. If the age and affinity of this specimen were proven to be correct, it would constitute the oldest record of this large and ecologically diverse monocotyledonous family.
Key results: Morphological features of the fossil (leaf dimensions, marginal spines, cuticular traces) indicate a close affinity with the extant bromeliad Aechmea magdalenae (André) André ex Baker. Leaf thickness (1.6 mm at maximum) suggests that K. bromelioides L. D. Gómez performed CAM photosynthesis. The geological information does not corroborate the estimated age and location of the specimen; the fossil is suggested to be of more recent origin.
Conclusions: The affinity of this fossil to Bromeliaceae was confirmed, but the uncertainties surrounding its age and collection locality mitigate against its use in inferences concerning the evolutionary history of the family.