​Goniopygus texanus Ikins & Clabaugh, 1940
Plate: GoTe-10
Series: Lower Cretaceous          Group: Fredericksburg                         Formation: Edwards
Locale: Austin                             County: Travis                                      Stage: Albian
Length: 18.3 mm                       Width: 8.5 mm                             
Specimen in photo: Collection of John Hinte
Repository: Private Collection
 
Plate: GoTe-20
Series: Lower Cretaceous          Group: Fredericksburg                         Formation: Edwards
Locale: Fluvanna                        County: Scurry                                     Stage: Albian
Length: 20.5 mm                       Width: 9.6 mm                             
Specimen in photo:                    William Thompson
Repository: Private Collection
 
HOLOTYPE INFO:
Holotype: BEG 20549 (Syntypes) — Non-vertebrate Paleontology Laboratory, University of Texas (Ikins, 1940)
Locality: 5 miles west of Austin, Travis County, Texas (Ikins, 1940)
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Echinacea Claus, 1876
Order: Arbacioida Gregory, 1900
Family: Acropeltidae Lambert, 1911
Genus: GONIOPYGUS L. Agassiz, 1838
Species: Goniopygus texanus Ikins & Clabaugh, 1940
TYPE SPECIES: Goniopygus major L. Agassiz, 1838
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Edwards Formation (Ikins, 1940)
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Travis County
DESCRIPTION
TOP: Length, width, height: 18.3 mm L × 10.5 mm H
Top shape: Test circular
SIDE: Ambitus: About 40% from flat bottom
BOTTOM: Flat
AMB: Amb shape: Lanceolate, straight; pointed towards corona, widest at ambitus
Amb primary tubercles: Two rows of tubercles between the two sets of pore pairs
INTERAMB: Interamb width: 1.5 times larger than ambulacra
PORE PAIRS: Shape: Slightly elongated
Arrangement: Uniserial, widely spaced; remain uniserial to peristome
TUBERCLES: Primary Perforated: No Imperforate
Primary Crenulate: Non-crenulate
Primary Mamelon: Mamelated
Size: Large tubercles at ambitus
APICAL SYSTEM: Location: Sits very high on corona of test
Plates: Genital plates large, pointed. Oculars deltoid shaped .
PERIPROCT (ANUS): Shape & Size: Oval with a slight point
PERISTOME (MOUTH): Size: 60% of bottom of test
Lip: Notches are on both sides of ambulacra
SPINES: Unknown
SPECIMENS STUDIED & CONDITION  Specimen in John Hinte Collection .
ETYMOLOGY  Named for the state of Texas (Ikins, 1940).
REMARKS & COMPARISONS
Remarks: Cooke (1946) considered both Goniopygus saleniaformis and Goniopygus texanus to be variants (likely immature individuals) of Goniopygus zitteli. They both possess fewer apical tubercles than G. zitteli.


Comparisons:

• G. saleniaformis: Has a suranal plate, which G. texanus lacks .

Remarks: Vadet, A. & Nicolleau, P., 2020 in Revision des Goniopygidae is proposing a method to classify and group Goniopygus species based on a specific biometric character: the size of the secondary tubercles in the ambulacral zone at the ambitus (equator). They lump all the Texas Albian/Cenomanian as (Cyphopygus zitteli) and that all others: (G. whitneyi, G. quartus, G. zitteli, G. texanus, G. saleniaformis, G. goodlandensis)  are just growth stages They all possess small secondary ambulacral tubercles, suggesting that spine morphology and secondary tubercle size are the true diagnostic features for separating these echinoids, rather than the minor differences in shape or pore arrangement often used by earlier authors (like Ikins or Whitney) to name new species.
Remarks: (01-26) The height of the apical disc cap sits high off the test on specimen from Travis County, (GoTe-10) and holotype, whereas, the apical disc cap sits even with the test on specimen from Scurry County (GoTe-20).