TABLE 4.

Results of 3D particle analysis of gas spaces within representative fronds scanned.

Line	Number of	Vol. (mm3)				Surface area (SA) (mm2)			Euler (χ)		Thickness (mm)
	gas spaces
		Min.	Median	Max.	Total	Min.	Median	Max.	Mean	Std. err.	Mean	Std. err.
S. intermedia	2187	4.25E–07	0.00003	0.02853	0.5822	0.00447	0.02763	4.963	0.9186	0.02292	0.08454	0.001251
L. punctata	3167	1.97E–07	1.1E–06	0.001	0.01173	0.000267	0.004	1.261	0.982	0.002526	0.02346	0.000272
L. minor	926	2.76E–07	4.53E–06	0.00105	0.01792	0.00159	0.00795	0.7155	0.9633	0.007848	0.0313	0.000209
W. lingulata	228	1.13E–08	5.65E–07	0.00042	0.00347	0.00019	0.00284	0.5657	0.9167	0.03213	0.03082	0.000523