Palaeos:		Porifera
Porifera		Calcarea

Calcarea

PORIFERA
|--Archaeocyatha  
`--+--Stromatoporoidea  
   `--+--Calcarea  
      `--+--Hexactinellida  
         `--+--Demospongiae  
            |  |--Tetractinomorpha  
            |  `--Ceractinomorpha  
            `--+--Homoscleromorpha  
               `--EUMETAZOA                      

Introduction

This class consists of marine calcareous sponges with a skeleton composed of massive calcite or separate calcareous spicules, not divisible into megascleres (larger) and microscleres (smaller).  They have an asconoid, syconoid or leuconoid construction. Many are dull coloured -- and some are, admittedly, just plain dull.  However, brilliant red, yellow, and lavender species are also known. In size they are generally smaller than representatives of other classes, most are less than 10 cm in height. They have a world-wide distribution, mostly restricted to shallow coastal waters. Possible Calcarea are known as early as the Tommotian. Wood (1998). 

Representative Orders

Calcarea 
     Heteractinida 
     Calcaronea 
     Pharetronida 
     Sphaerocoelida

classification according to  Synopsis of the described taxa of the world

Calcarea
     Innaecoelida     (extinct)
     Solenida         (extinct)
     Poratida         (no fossil record)
     Clathrinida      (no fossil record)
     Pharetronida     (extinct)
     Murrayonida      (no fossil record)
     Leucosoleniida 
     Heteractinida    (extinct)
     Lithonida       
     Permosphincta    (extinct)
     Sphaerocoelida   (extinct)
     Clathodictyida   (extinct)

Permosphincta may be Demospongiae? (see  Palaeontographica Canadiana No. 16 "Silurian Wenlock demosponges from the Avalanche Lake area of the Mackenzie Mountains southwestern District of Mackenzie Northwest Territories Canada."

Order Pharetronida

In this large group the spicules form a closely packed mesh of different sized "tuning forks", giving a rigid skeleton.  During the Jurassic these sponges formed large reefs

(includes the genera Stellispongia, Myrmecium, Elasmostoma, Corynella, Raphidonema, Peronidella, Porosphaera, Petrostoma, etc)

Order Thalamida

Cladogram

<===o CALCAREA 
   |--o CALCINIA
   |  |--o CLATHRINIDA
   |  |  `-- Clathrinidae*
   |  `--o LEUCETTIDA
   |     |-- Leucaltidae
   |     |-- Leucascidae
   |     `-- Leucettidae
   |--o CALCARONIA
   |  |--o LEUCOSOLENIIDA
   |  |  `-- Leucosoleniidae*
   |  `--o SYCETTIDA
   |     |-- Sycettidae
   |     |-- Heteropiidae
   |     |-- Grantiidae
   |     |-- Amphoriscidae
   |     `-- Lelapiidae
   |--o PHARETRONIDIA
   |  `--o INOZOIDA
   |     |-- Murrayonidae
   |     |-- Paramurrayonidae
   |     |-- Minchinellidae
   |     |-- Petrobionidae
   |     `-- Lepidoleuconidae
   `--o SPHINCTOZOA
      `--o PORATIDA*
         `-- Neocoeliidae

Links

Calcarea - Curt Smecher's summary

Parker, Sybil P. (ed.), 1982: Synopsis and Classification of Living Organisms. New York: McGraw-Hill Book Co., 2 vols.

Invertebrate Zoology by Edward E. Ruppert, Robert D. Barnes

Calcarea