Taxonomy

Phylum: Porifera Grant,1836

Class: Demospongea Sollas, 1875

Order: Monaxonida Sollas, 1883

Family: Quadrolaminiellidae Chen,Hou et Li,1990

Genus: Quadrolaminiella Chen,Hou et Li,1990

Specie: Quadrolaminiella diagonalis Chen,Hou et Li,1990

Description: 

This large, elongate, ellipsoidal sponge is known from a few tens of specimens.

Q. diagonalis ocurrs as two‐dimensional impression fossils up to 30 cm long and about 12 cm wide, narrowing proximally and also distally toward the presumed site of the osculum. The skeleton consists of four layers of single‐axis(monaxon) spicules, arranged into two nets each of two layers. The spicules of the outermost layer are coarse, relatively widely spaced and extend virtually the entire length of the sponge; those of the second layer are finer, more closely spaced and horizontal. The spicules of the two layers of the inner net trend diagonally in opposite directions.

Quadrolaminiella is the only known genus of the Quadrolaminiellidae. The genus was originally considered to be a demosponge, possibly derived from Leptomitus‐like forms by the development of, inter alia, a thicker skeleton. Quadrolaminiella has also been compared with Cambrian hexactinellids.

The life position of Q. diagonalis was probably vertical, anchored to the substrate at its relatively narrow basal region.

Q. diagonalis is one of two Quadrolaminiella species,both of which are found only in the Chengjiang biota.

Age & Localities

Age: Cambrian Series2, Stage3

Principal localities: Chengjiang biota (Yu’anshan Member of the Chiungchussu Formation),eastern Yunan Province,China