02493nas a2200193 4500008004100000245007000041210006900111260006700180490000600247520188400253653001402137653001302151653001702164653001502181653001502196100002002211700002502231856004302256 2013 eng d00aWhy is the tropical Cenozoic fossil record so poor for bryozoans?0 aWhy is the tropical Cenozoic fossil record so poor for bryozoans aCatania, ItalybMuseo Tridentino di Scienze Naturalicin press0 v13 a
Diverse bryozoan assemblages have been recorded from widely across the Cenozoic palaeotropics, including the West Indies and Central America (Miocene-Pleistocene), Arabia (Oligocene), East Africa (Miocene), India (Eocene-Miocene) and the East Indies (Eocene-Miocene). However, records of Cenozoic tropical bryofaunas are relatively few compared with higher latitudes, and bryozoan limestones seem to be lacking. Insights into the reasons for this poor fossil record can be gleaned from comparisons with modern tropical bryozoan faunas, and consideration of the effects of diagenesis on fossil preservation and other factors that bias against the tropical Cenozoic fossil record. At least for the North Atlantic, bryozoan assemblage diversity in the modern tropics is not significantly less than in higher latitudes. However, a survey of colony-forms shows that encrusting species of small biomass are more dominant in tropical assemblages (mean 78% of species) than they are outside the tropics (mean 60% of species). These encrusting colonies may be difficult to observe and study when, as is often the case in tropical carbonate settings, diagenetic cement binds sediment firmly to the colony surfaces. Most erect bryozoan species living today in the tropics have weakly mineralized skeletons with a poor potential for fossilization; robust species capable of generating large quantities of carbonate sediment are uncommon. In addition, a higher proportion of cheilostomes in the tropics have metastable skeletons of aragonite: a Raman spectroscopic survey of 23 bryozoan species encrusting the undersides of platy corals from Puerto Rico and Malaysia showed 30% to be aragonitic and 27% bimineralic. Along with the typically higher Mg levels in the calcite of tropical cheilostomes, this further biases against preservation of bryozoans in the Cenozoic fossil record.
10aBryozoans10aCenozoic10acolony-forms10adiagenesis10amineralogy1 aTaylor, Paul, D1 aDi Martino, Emanuela uhttps://ipaeg.myspecies.info/node/203500573nas a2200157 4500008004100000245007400041210006900115260004200184653001200226653001300238653001400251653001400265100002000279700002500299856009100324 2012 eng d00aAn overview of the Cenozoic fossil record of bryozoans in the tropics0 aoverview of the Cenozoic fossil record of bryozoans in the tropi aCharlotte, North Carolinac04/11/201210aBRYOZOA10aCenozoic10aEvolution10aTaphonomy1 aTaylor, Paul, D1 aDi Martino, Emanuela uhttps://ipaeg.myspecies.info/content/overview-cenozoic-fossil-record-bryozoans-tropics