Sea-level estimates and seafloor species richness follow a shared rhythm of about 2 million years in a peer-reviewed reconstruction of the Cambrian SPICE interval. Geological measurements from the North China Block were placed on an astronomical timescale and compared with biodiversity data. The temporal association depends on age alignment and does not establish a precise ecological response time.
Sea-level change and marine biodiversity show a shared rhythm during a major Cambrian carbon-cycle disturbance. The peer-reviewed study compares geological measurements with the richness of species living on the seafloor. Its focus is the SPICE interval, named for the Steptoean Positive Carbon Isotope Excursion, a pronounced change in the proportions of carbon isotopes preserved in marine rocks.[1], [2]
Measurements of carbonate carbon isotopes and sediment cycles from the North China Block, an ancient geological region in present-day China, were placed on an astronomical timescale. Fossil zones helped constrain the ages. Comparing reconstructed sea-level variation with benthic species richness revealed a common cycle lasting about 2 million years. The analysis combines environmental proxies with biodiversity compilations rather than observing individual organisms responding to a measured water-level change.[1]
The closest statistical fit placed sea-level change about 70,000 years ahead of biodiversity change. The authors treat that offset as model-dependent: age interpolation, filtering, measurement resolution and the unknown response timing of each proxy can affect its magnitude and even its direction. Variable sediment accumulation and later mineral alteration can also distort the carbon-isotope signal. The reconstruction therefore supports a temporal association without uniquely identifying an ecological delay or proving direct causation.[1]
