Tetragramma taffi (Cragin, 1893)
Plate: TeTa-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Walnut
Locale: Goldthwaite County: Mills Stage: Albian
Length: 63.0 mm Height: 33.7 mm
Specimen in photos: Collection of Danny Harlow Repository: Private
Specimen adoral view: Collection of Terry Stephenson Repository: Private
Plate: TeTa-20
Series: Lower Cretaceous Group: Fredericksburg Formation: Comanche Peak
Locale: North San Gabriel River County: Williamson Stage: Albian
Length: 59.0 mm Height: 26.0 mm
Repository: USNM USGS Holotype
HOLOTYPE INFO:
Holotype: Originally collected by J.A. Taff (Cragin, 1893). Specimen likely at USNM or UT (BEG).
Locality: North San Gabriel River, 3 miles above Georgetown, Williamson County, Texas.
Stratigraphy: Rocks of the Fredericksburg division (Comanche Peak Limestone).
SYNONYMY
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Diplopodiidae Smith & Wright, 1993
Genus: TETRAGRAMMA L. Agassiz, 1838
Species: Tetragramma taffi (Cragin, 1893)
TYPE SPECIES: Cidarites variolare Brongniart, 1822
DIAGNOSIS
A large, low, subcircular Tetragramma. Pore pairs biserial above and at the ambitus, becoming uniserial below. Interambulacra typically bear 8 rows of primary tubercles, expanding to 10 rows in very large individuals. Ambulacra narrow with two rows of primary tubercles. Distinguished from T. malbosii by deeper peristomial emarginations, broader miliary zones, and a different proportional reduction of the fourth interambulacral row.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg; Trinity (Rare).
Formations: Comanche Peak Limestone; Walnut Formation; Glen Rose Formation (upper).
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Williamson, Mills, Bandera, Tarrant, Hill, Borden.
Abundance: Uncommon; described by Cragin (1893) as "much the largest known Diplopodia of the Texas Cretaceous."
DESCRIPTION
TOP: Length, width, height: 63.0 mm L × 33.7 mm H (TeTa-10). Top shape: Subcircular; disc but little elongated (Cragin, 1893). Top domed: Large, low; superior part of the test slightly arched. Test is swollen around the apical scar.
SIDE: Side shape: Somewhat inflated; lateral walls not strongly bulging.
BOTTOM: Bottom shape: Flattened (Clark & Twitchell, 1915).
AMB: Amb shape: Moderate width. Amb arrangement: Two vertical rows of primary tubercles. Breadth of ambulacral area contained two and two-thirds to three times in that of the interambulacral (Cragin, 1893).
PORE PAIRS: Arrangement: Pore pairs doubled (biserial) above and on the ambitus; belts rather broader in the latter position than elsewhere. Becomes gradually simple (uniserial) below the ambitus (Cragin, 1893).
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes. Interambulacral Tubercles: Ornamented with three vertical rows of large tubercles and a fourth row of smaller primary tubercles near the ambulacral border (totaling 8 rows). The fourth row is more diminished relative to the three than in T. malbosii (Cragin, 1893). Book Author notes that extra-large specimens exhibit 10 rows at the margin.
GRANULES: Distribution: Breadth of miliary zone equal to that occupied by the three principal rows of tubercles; bears a short row of quite small tubercles on one or both sides of the median suture (Cragin, 1893).
FASCIOLE: Absent.
APICAL SYSTEM: Size: Moderate; less than one-third the breadth of the test (17 mm in Type). Shape: Median and maximum transverse diameters about equal. Features: Posterior sinus and corresponding miliary sulcus but little larger than the others (Cragin, 1893).
PERIPROCT (ANUS): (Unknown).
PERISTOME (MOUTH): Size: A little more than one-fourth as broad as the entire test (16.6 mm in Type). Lip: Emarginations of its interambulacral border are considerably deeper than in T. malbosii (Cragin, 1893).
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION:
ETYMOLOGY
Named in honor of Joseph Alexander Taff (1862–1944), geologist with the Geological Survey of Texas, who discovered the type specimen (Cragin, 1893).
REMARKS & COMPARISONS
Remarks: Tetragramma taffi is the largest Texas species of the genus and one of the most heavily ornamented, with 8–10 rows of interambulacral tubercles in large individuals. The species shows a consistent combination of:
Comparisons:
• Tetragramma malbosii (Europe): T. taffi has deeper peristomial emarginations, a broader miliary zone, and a more reduced fourth interambulacral row. The European species is more inflated and has a slightly different apical system proportion.
• Tetragramma streeruwitzi (West Texas): T. streeruwitzi is much more depressed, with 8–10 rows arranged differently and a narrow, elongate apical scar. T. taffi is higher, broader, and has deeper peristomial notches.
• Tetragramma goodlandense: T. goodlandense has six rows plus secondary rows and a more flattened test. T. taffi is larger, more inflated, and has a more complex row expansion (8–10 rows).
• Tetragramma hammerschmidti: T. hammerschmidti has six rows with high tubercle counts but is smaller and more inflated. T. taffi is larger, lower, and has more rows in large individuals.
• Tetragramma glenrosense: T. glenrosense has only four rows and a more pentagonal apical system. T. taffi is much larger and more heavily ornamented.
• Tetragramma cranei: T. cranei is small, very flattened, and has a 12–9–5 row pattern. T. taffi is far larger and more inflated, with 8–10 rows.
Plate: TeTa-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Walnut
Locale: Goldthwaite County: Mills Stage: Albian
Length: 63.0 mm Height: 33.7 mm
Specimen in photos: Collection of Danny Harlow Repository: Private
Specimen adoral view: Collection of Terry Stephenson Repository: Private
Plate: TeTa-20
Series: Lower Cretaceous Group: Fredericksburg Formation: Comanche Peak
Locale: North San Gabriel River County: Williamson Stage: Albian
Length: 59.0 mm Height: 26.0 mm
Repository: USNM USGS Holotype
HOLOTYPE INFO:
Holotype: Originally collected by J.A. Taff (Cragin, 1893). Specimen likely at USNM or UT (BEG).
Locality: North San Gabriel River, 3 miles above Georgetown, Williamson County, Texas.
Stratigraphy: Rocks of the Fredericksburg division (Comanche Peak Limestone).
SYNONYMY
- Diplopodia taffi Cragin, 1893
- Tetragramma taffi (Cragin) Cooke, 1946
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Diplopodiidae Smith & Wright, 1993
Genus: TETRAGRAMMA L. Agassiz, 1838
Species: Tetragramma taffi (Cragin, 1893)
TYPE SPECIES: Cidarites variolare Brongniart, 1822
DIAGNOSIS
A large, low, subcircular Tetragramma. Pore pairs biserial above and at the ambitus, becoming uniserial below. Interambulacra typically bear 8 rows of primary tubercles, expanding to 10 rows in very large individuals. Ambulacra narrow with two rows of primary tubercles. Distinguished from T. malbosii by deeper peristomial emarginations, broader miliary zones, and a different proportional reduction of the fourth interambulacral row.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg; Trinity (Rare).
Formations: Comanche Peak Limestone; Walnut Formation; Glen Rose Formation (upper).
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Williamson, Mills, Bandera, Tarrant, Hill, Borden.
Abundance: Uncommon; described by Cragin (1893) as "much the largest known Diplopodia of the Texas Cretaceous."
DESCRIPTION
TOP: Length, width, height: 63.0 mm L × 33.7 mm H (TeTa-10). Top shape: Subcircular; disc but little elongated (Cragin, 1893). Top domed: Large, low; superior part of the test slightly arched. Test is swollen around the apical scar.
SIDE: Side shape: Somewhat inflated; lateral walls not strongly bulging.
BOTTOM: Bottom shape: Flattened (Clark & Twitchell, 1915).
AMB: Amb shape: Moderate width. Amb arrangement: Two vertical rows of primary tubercles. Breadth of ambulacral area contained two and two-thirds to three times in that of the interambulacral (Cragin, 1893).
PORE PAIRS: Arrangement: Pore pairs doubled (biserial) above and on the ambitus; belts rather broader in the latter position than elsewhere. Becomes gradually simple (uniserial) below the ambitus (Cragin, 1893).
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes. Interambulacral Tubercles: Ornamented with three vertical rows of large tubercles and a fourth row of smaller primary tubercles near the ambulacral border (totaling 8 rows). The fourth row is more diminished relative to the three than in T. malbosii (Cragin, 1893). Book Author notes that extra-large specimens exhibit 10 rows at the margin.
GRANULES: Distribution: Breadth of miliary zone equal to that occupied by the three principal rows of tubercles; bears a short row of quite small tubercles on one or both sides of the median suture (Cragin, 1893).
FASCIOLE: Absent.
APICAL SYSTEM: Size: Moderate; less than one-third the breadth of the test (17 mm in Type). Shape: Median and maximum transverse diameters about equal. Features: Posterior sinus and corresponding miliary sulcus but little larger than the others (Cragin, 1893).
PERIPROCT (ANUS): (Unknown).
PERISTOME (MOUTH): Size: A little more than one-fourth as broad as the entire test (16.6 mm in Type). Lip: Emarginations of its interambulacral border are considerably deeper than in T. malbosii (Cragin, 1893).
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION:
- Plate TeTa-10: Walnut Fm, Mills Co. (Coll. Danny Harlow).
- Plate TeTa-20: Glen Rose Fm, Bandera Co. (NPL 97949).
- Plate TeTa-30: Comanche Peak Fm, Williamson Co. (USGS Holotype).
ETYMOLOGY
Named in honor of Joseph Alexander Taff (1862–1944), geologist with the Geological Survey of Texas, who discovered the type specimen (Cragin, 1893).
REMARKS & COMPARISONS
Remarks: Tetragramma taffi is the largest Texas species of the genus and one of the most heavily ornamented, with 8–10 rows of interambulacral tubercles in large individuals. The species shows a consistent combination of:
- a low, broad test,
- wide miliary zones,
- deep peristomial emarginations, and
- a moderate apical system with nearly equal diameters.
Comparisons:
• Tetragramma malbosii (Europe): T. taffi has deeper peristomial emarginations, a broader miliary zone, and a more reduced fourth interambulacral row. The European species is more inflated and has a slightly different apical system proportion.
• Tetragramma streeruwitzi (West Texas): T. streeruwitzi is much more depressed, with 8–10 rows arranged differently and a narrow, elongate apical scar. T. taffi is higher, broader, and has deeper peristomial notches.
• Tetragramma goodlandense: T. goodlandense has six rows plus secondary rows and a more flattened test. T. taffi is larger, more inflated, and has a more complex row expansion (8–10 rows).
• Tetragramma hammerschmidti: T. hammerschmidti has six rows with high tubercle counts but is smaller and more inflated. T. taffi is larger, lower, and has more rows in large individuals.
• Tetragramma glenrosense: T. glenrosense has only four rows and a more pentagonal apical system. T. taffi is much larger and more heavily ornamented.
• Tetragramma cranei: T. cranei is small, very flattened, and has a 12–9–5 row pattern. T. taffi is far larger and more inflated, with 8–10 rows.
