3 Stromatoporoidea Types & Characteristics

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A widespread group of ancient sea sponges found in the Ordovician to the Devonian fossil record is Stromatoporoidea. Let us see their types below.

  • Amphipora stromatoporoids
  • Palaeozoic stromatoporoids
  • Massive stromatoporoids 

Amphipora Stromatoporoids

Various kinds of stromatoporoids are a result of genetic and environmental mix. The Devonian stromatoporoids, also known as Amphipora stromatoporoids were branching forms. They most likely lived in lagoons because of their fragile morphology, which could not have survived turbulence in the water.

Palaeozoic stromatoporoids

The enormous basal skeletons of Palaeozoic stromatoporoids have been observed in a variety of shapes. Stromatoporoids are frequently regarded as helpful palaeoenvironmental markers since their exterior forms and other characteristics are, in some ways, largely controlled by environmental conditions.

Massive stromatoporoids

Massive basal stromatoporoid skeletons are laminar, domical or bulbous in form. According to the proportions of three dimensions measured in the horizontal, vertical, and diagonal aspects on a vertical crosscut across a whole skeleton, a specimen is classified as having a certain form.

701px Stromatoporoid fossil Colu
Image credits: Stromatoporoidea James St. John, (CC BY 2.0) from Wikimedia Commons

Characteristics

An extinct class of sponges known as stromatoporoid were composed of a rigid, compact structure. Let us see more about their characteristics below.

  • The stromatoporoid possessed enormous calcareous skeletons, which have been preserved as very noticeable fossils.
  • Domes larger than 5 metres in diameter were created by certain stromatoporoids. By releasing calcium carbonate sheets, the stromatoporoid expanded.
  • The rod-like pillars perpendicular to the laminae and layers known as laminae is parallel to the substrate that was produced.
  • The skeleton layers that were closest to the surface likely held live tissue, whereas the layers that were farther away from the surface seem to have been backfilled with calcite.
  • Stromatoporoids have elevated structures termed “mamelons” on the surface of the skeleton, which housed the majority of the living tissue and is thought to have been the location of excurrent apertures.
  • The astrorhizal canals are related to melons. Astrosclera excurrent canal systems are represented by very comparable structures seen on live sponges.
  • Paleozoic and Mesozoic stromatoporoids are the two primary subgroups that can be found in fossil form.
  • The Ordovician marks the beginning of the previous group’s fossil record, which lasts until the Early Carboniferous. The Paleozoic stromatoporoids emerged, soon rose to the top of the reef-building food chain, and remained there for more than 100 million years.
  • The Mesozoic stromatoporoids play a significant role in the development of reefs, particularly during the Cretaceous.
  • A number of current sponges would be categorised as stromatoporoids in this second group, and they may be attributed to Demospongia based on soft portions. Their variety is reflected in the evolution of Demospongia as a whole.

Conclusion

From above article, it can be concluded that, the most well-known feature of stromatoporoids is that they were the main reef-building creatures from the Middle Ordovician to the Late Devonian, until being nearly completely wiped out during the Late Devonian mass extinction.

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