Reticulosa Explained

Reticulosa is an extinct order of sea sponges in the class Hexactinellida (glass sponges) and the subclass Amphidiscophora.^{[1] [2]} Reticulosans were diverse in shape and size, similar to their modern relatives, the amphidiscosidans. Some were smooth and attached to a surface at a flat point, others were polyhedral or ornamented with nodes, many were covered in bristles, and a few were even suspended above the seabed by a rope-like anchor of braided glass spicules.

Reticulosans comprise the vast majority of Paleozoic hexactinellid diversity, though only a few species survived up to the Mesozoic.^[3] They may include the oldest sponge body fossil in the world: Palaeophragmodictya, from the late Ediacaran (~555 Ma), was originally described as a reticulosan based on its mesh-like surface texture.^[4] Ediacaran-type preservation has obscured any information about spicule structure, and some authors doubt that Palaeophragmodictya is a sponge in the first place.^{[5] [6] [7]} Regardless, unambiguous reticulosans appear in the fossil record not much later, in the early Cambrian.

Like most other glass sponges, reticulosans had a skeleton of unfused macroscleres reinforced with microscopic microscleres. Their macroscleres are often stauractines (four-rayed spicules, + shaped), though pentactine (five-rayed) or hexactine (six-rayed) spicules may be predominant in certain regions of the skeleton. The outer layer of the skeleton forms a regular mesh-like pattern, with incrementally smaller spicules filling in the gaps between larger spicules in a fractal pattern. The microscleres, when present, are simple bundled rods (paraclavules).

The living glass sponge Sclerothamnus is sometimes compared to the reticulosan family Titusvillidae,^[8] though it is more commonly placed in the family Tretodictyidae of the order Sceptrulophora.^[9]

Subgroups

From the Treatise on Invertebrate Paleontology (2004), unless otherwise noted:

• Superfamily †Dictyospongioidea Hall & Clarke, 1899
  • Family †Dictyospongiidae Hall & Clarke, 1899 [Ediacaran?–Middle Permian (Roadian)]
  • Family †Docodermatidae Finks, 1960 [Silurian (Ludlow)–Permian]
  • Family †Stereodictyidae Finks, 1960 [Carboniferous (Visean)–Upper Triassic (Carnian)]
• Superfamily †Dierespongioidea Rigby & Gutschick, 1976
  • Family †Aglithodictyidae Hall & Clarke, 1899 [Upper Devonian–Carboniferous (Visean)]
  • Family †Amphispongiidae Rauff, 1894 [upper Silurian]
  • Family †Dierespongiidae Rigby & Gutschick, 1976 [Middle Ordovician–Lower Permian (Artinskian)]
  • Family †Hydnodictyidae Rigby, 1971 [middle Cambrian–Upper Ordovician]
  • Family †Multivasculatidae Laubenfels, 1955 [upper Cambrian]
  • Family †Titusvillidae Caster, 1939 [Upper Devonian–Lower Mississippian, Holocene?]
• Superfamily †Hintzespongioidea Finks, 1983
  • Family †Hintzespongiidae Finks, 1983 [lower Cambrian–Middle Devonian (Givetian)]
  • Family †Teganiidae Laubenfels, 1955 [upper Cambrian (Furongian)–Upper Mississippian]
• Superfamily †Protospongioidea Hinde, 1887
  • Family †Asthenospongiidae? Botting, 2004^[10] [Ordovician]
  • Family †Protospongiidae Hinde, 1887 [lower Cambrian–Jurassic]
  • Family †Triactinellidae? _{Botting, 2005}^[11] [Ordovician]

Notes and References

1. Web site: Fossilworks: Reticulosa. fossilworks.org. 17 December 2021.
2. Treatise on Invertebrate Paleontology Part E, Revised. Porifera, Volume 3: Classes Demospongea, Hexactinellida, Heteractinida & Calcarea, xxxi + 872 p., 506 fig., 1 table, 2004, available here. .
3. Treatise on Invertebrate Paleontology Part E, Revised. Porifera, Volume 2: Introduction to the Porifera, xxvii + 349 p., 135 fig., 10 tables, 2003, available here. .
4. Gehling . James G. . Rigby . J. Keith . March 1996 . Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia . Journal of Paleontology . en . 70 . 2 . 185–195 . 10.1017/S0022336000023283 . 0022-3360.
5. Serezhnikova . E. A. . 2007 . Palaeophragmodictya spinosa sp. nov., a bilateral benthic organism from the Vendian of the Southeastern White Sea Region . Paleontological Journal . en . 41 . 4 . 360–369 . 10.1134/S0031030107040028 . 0031-0301.
6. Antcliffe . Jonathan B. . Callow . Richard H. T. . Brasier . Martin D. . 2014 . Giving the early fossil record of sponges a squeeze: The early fossil record of sponges . Biological Reviews . en . 89 . 4 . 972–1004 . 10.1111/brv.12090.
7. Cunningham . John A. . Liu . Alexander G. . Bengtson . Stefan . Donoghue . Philip C. J. . 2017 . The origin of animals: Can molecular clocks and the fossil record be reconciled? . BioEssays . en . 39 . 1 . e201600120 . 10.1002/bies.201600120. free .
8. Burr . Sande A. . Chiment . John J. . Allmon . Warren D. . Rigby . J. Keith . 2003 . A Problematic Fossil Brings Paleontology to the Classroom and the World . Journal of Geoscience Education . en . 51 . 4 . 361–364 . 10.5408/1089-9995-51.4.361 . 1089-9995.
9. Reid . R.E.H. . 1961 . Notes on Hexactinellid sponges—III. Seven Hexactinosa . Annals and Magazine of Natural History . 4 . 48 . 739–747 . 10.1080/00222936108651201 . 0374-5481.
10. Botting . Joseph P. . 2004 . An exceptional caradoc sponge fauna from the llanfawr quarries, central wales and phylogenetic implications . Journal of Systematic Palaeontology . en . 2 . 1 . 31–63 . 10.1017/S147720190300110X . 1477-2019. subscription .
11. Botting . Joseph P. . 2005 . EXCEPTIONALLY WELL-PRESERVED MIDDLE ORDOVICIAN SPONGES FROM THE LLANDEGLEY ROCKS LAGERSTATTE, WALES . Palaeontology . en . 48 . 3 . 577–617 . 10.1111/j.1475-4983.2005.00470.x . 0031-0239.