Skip to main content

Table 1 Comparison of morphological characters in Clypeaster sarawakensis nov. sp. with Clypeaster species present in (a) the Central Indo-Pacific fossil record, and (b) the modern Central Indo-Pacific and analysed in Mihaljević et al. (2011)

From: A new fossil species of Clypeaster (Echinoidea) from Malaysian Borneo and an overview of the Central Indo-Pacific echinoid fossil record

Morphological characters Clypeaster sarawakensis F Clypeaster annandalei M Clypeaster blumenthali F Clypeaster brevipetalus F Clypeaster fervens M Clypeaster humilis F M Clypeaster latissimus F M
Marginal buttressing Extent of marginal buttressing Series of walls forming a wide buttressed zone Series of walls forming a wide buttressed zone NA NA Single internal wall around part or all of test* Series of walls forming a wide buttressed zone Series of walls forming a wide buttressed zone
Ambulacral buttress organization Bar(s) Aligned pillars* NA NA Aligned pillars* Bar(s) Bar(s)
Internal wall effectively forming a double wall with microcanal system ?No No NA NA No No No
Radial bars projecting in from test margin along adradial sutures Absent Absent NA NA Along just posterior interambulacrum (periproctal)* Absent Absent
Central buttresing Central buttressing structures Present Present NA NA Present Present Present
Central buttressing of interambulacral zones Infill of relatively fine pillars + bars in interradial zone Dominated by large adradial bars/pillars bounding lower ends of petals* NA NA Infill of relatively fine pillars + bars in interradial zone Dominated by large adradial bars/pillars bounding lower ends of petals* Infill of relatively fine pillars + bars in interradial zone
Central buttressing fused to form an almost continuous curtain enclosing petaloid area: No No NA NA No No No
Central ambulacral zones within petals Fine pillars only No buttressing* NA NA Fine pillars only No buttressing* Fine pillars only
Petals Distance from distal end of petal III to ambitus vs. length of petal III: ~ 0.46 (petals end midway to ambitus) 0.35–0.65 0.35–0.65 > 0.7—petals end far from ambitus* 0.35–0.65 0.35–0.65 0.35– > 0.7
Petal III opened or closed - distance between inner pore-pairs vs. max broadness of inner 1-petals  ~ 0.25 (relatively closed) 0.76–0.95—widely open* 0.76–0.95—widely open* < 0.15—almost closed* 0.76–0.95—widely open* < 0.15—almost closed* < 0.15—almost closed*
Petal II opened or closed -distance between inner pore-pairs vs. max broadness of inner petals  ~ 0.25 (relatively closed) 0.15–0.75 0.76–0.95* < 0.15* < 0.15* < 0.15* < 0.15*
Number of occluded plates in petal II NA 1–6 ?1–6 ?1–6 >6 >6 >6
Demi-plates in petals Present Present ?Present ?Present Present Present Present
Test shape Sunkeness of oral surface Flat outer region with inturned test close to the peristome Flat outer region with inturned test close to the peristome Flat outer region with inturned test close to the peristome NA Test with broad adoral concavity* Flat outer region with inturned test close to the peristome Flat outer region with inturned test close to the peristome
Angle of peristome to point of contact 5°–10° 0°* 0°* NA > 10°* 5°–10° 0°*
Peripheral swollen rim Present Absent Absent Absent* Absent* Absent* Absent*
Thickness of the test edge Rounded Thin/sharp* Rounded Thin/sharp* Rounded Thin/sharp* Thin/sharp*
Food grooves Food grooves Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only
S/T ratio (distance of distal end of the food groove to ambitus vs. distance of peristome to ambitus)  ~ 0.33 < 0.35—food groove extends almost to ambitus < 0.35—food groove extends almost to ambitus NA 0.4–0.7* < 0.35—food groove extends almost to ambitus < 0.35—food groove extends almost to ambitus
Combed area Absent Absent Absent NA Absent Absent Absent
Tubercle differentiation along ambulacra NA Present, pores in distinct V-shaped region on each plate Absent; pores scattered across plates NA Absent; pores scattered across plates Present, pores in distinct V-shaped region on each plate Present, pores in distinct V-shaped region on each plate
Periproct Distance to ambitus from periproct/periproct length ~ 0.64 0.8–1.5 < 0.8 NA < 0.8 < 0.8–1.5 > 1.5*
Situated between plates NA 4b and 3a ?4b and 3a NA 4b and 4a 4b and 4a 4b and 4a
Situated On oral surface On oral surface On oral surface On oral surface On oral surface on oral surface On oral surface
Tract of digestive system Gut coiling Runs anteriorly and loops back before reaching perradius of ambulacrum III Runs anteriorly and loops back before reaching perradius of ambulacrum III NA NA Comes out slightly left of centre and loops around front (crosses perradius of ambulacrum III)* Comes out slightly left of centre and loops around front (crosses perradius of ambulacrum III)* Runs anteriorly and loops back before reaching perradius of ambulacrum III
Apical disc Number of gonopores 5 5 5 5 5 5 5
Lantern support structures Lantern supports Paired Paired ?Paired ?Paired Paired Paired Paired
Interambulacral plates Aboral surface composed of Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates
Morphological characters Clypeaster cf. malumbangensisF Clypeaster miniaceus M Clypeaster pateriformis M Clypeaster phyllodes F Clypeaster rarispinus M Clypeaster reticulatus F M Clypeaster saipanicus F
Marginal buttressing Extent of marginal buttressing NA Series of walls forming a wide buttressed zone Series of walls forming a wide buttressed zone ?Series of walls forming a wide buttressed zone* Series of walls forming a wide buttressed zone Absent* NA
Ambulacral buttress organization NA Bar(s) Bar(s) NA Bar(s) NA
Internal wall effectively forming a double wall with microcanal system NA No No NA No No NA
Radial bars projecting in from test margin along adradial sutures NA Along just posterior interambulacrum (periproctal)* Absent NA Absent Along just posterior interambulacrum (periproctal)* NA
Central buttresing Central buttressing structures NA Present Present NA Present Present NA
Central buttressing of interambulacral zones NA Dominated by large adradial bars/pillars bounding lower ends of petals* Infill of relatively fine pillars + bars in interradial zone NA Infill of relatively fine pillars + bars in interradial zone Dominated by large adradial bars/pillars bounding lower ends of petals* NA
Central buttressing fused to form an almost continuous curtain enclosing petaloid area: NA No No NA No No NA
Central ambulacral zones within petals NA No buttressing* Fine pillars only NA Fine pillars only No buttressing* NA
Petals Distance from distal end of petal III to ambitus vs. length of petal III: > 0.7—petals end far from ambitus* > 0.7—petals end far from ambitus* > 0.7—Petals end far from ambitus* > 0.7—Petals end far from ambitus* > 0.7—Petals end far from ambitus* 0.35–0.65 0.35–0.65
Petal III opened or closed - distance between inner pore-pairs vs. max broadness of inner 1-petals < 0.15—Almost closed* 0.76–0.95—Widely open* < 0.15—Almost closed* ? < 0.15—Almost closed < 0.15—Almost closed* < 0.15—Almost closed* NA
Petal II opened or closed -distance between inner pore-pairs vs. max broadness of inner petals < 0.15* < 0.15* < 0.15* 0.15–0.75 < 0.15—Almost closed* < 0.15* 0.15–0.75
Number of occluded plates in petal II ?1–6 1–6 ?1–6 ?1–6 1–6 1–6 ?1–6
Demi-plates in petals Present Present Present Present Present Present ?Present
Test shape Sunkeness of oral surface NA Flat outer region with inturned test close to the peristome Flat outer region with inturned test close to the peristome Flat outer region with inturned test close to the peristome Flat outer region with inturned test close to the peristome Test with broad adoral concavity* Test with broad adoral concavity*
Angle of peristome to point of contact NA 5°–10° ?5°–10°* 5°–10° 0°* 5°–10° ? > 10°*
Peripheral swollen rim Absent* Absent* Absent* Absent* Present Present Absent*
Thickness of the test edge ?Rounded Rounded* ?Thin/sharp* Rounded Rounded Rounded Rounded
Food grooves Food grooves Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only Present on oral surface only
S/T ratio (distance of distal end of the food groove to ambitus vs. distance of peristome to ambitus) NA 0.4–0.7* < 0.35—Food groove extends almost to ambitus NA < 0.35—Food groove extends almost to ambitus > 0.7—Food groove confined to adoral region ? > 0.7—Food groove confined to adoral region*
Combed area NA Absent Absent Absent Absent Absent Absent
Tubercle differentiation along ambulacra NA Present, pores in distinct V-shaped region on each plate ?Absent; pores scattered across plates ?Absent; pores scattered across plates Resent, pores in distinct V-shaped region on each plate Absent; pores scattered across plates ?Absent; pores scattered across plates
Periproct Distance to ambitus from periproct/periproct length NA 0.8–1.5 > 1.5* 0.8–1.5 <0.8 0.8–1.5 0.8–1.5*
Situated between plates NA 5b and 4a NA NA 4b and 3a 4b and 3a NA
Situated On oral surface On oral surface On oral surface On oral surface On oral surface On oral surface On oral surface
Tract of digestive system Gut coiling NA runs anteriorly and loops back before reaching perradius of ambulacrum III runs anteriorly and loops back before reaching perradius of ambulacrum III NA Comes out slightly left of centre and loops around front (crosses perradius of ambulacrum III)* Comes out slightly left of centre and loops around front (crosses perradius of ambulacrum III) NA
Apical disc Number of gonopores 5 5 5 5 5 5 ?5
Lantern support structures Lantern supports ?Paired Paired ?Paired ?Paired Paired Paired ?Paired
Interambulacral plates Aboral surface composed of Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates ambulacral and interambulacral columns of plates Ambulacral and interambulacral columns of plates
  1. Detailed description of morphological characters used can be found in Mihaljević et al. (2011)
  2. NA refers to characters that were not available due to poor preservation of the fossil specimen
  3. *Characters that differ to Clypeaster sarawakensis
  4. Inapplicable
  5. ? indicates uncertainty in character scoring
  6. FFossil species
  7. MModern species