Gastonia

Cretaceous Period Herbivore Creature Type

Gastonia burgei

Scientific Name: "Genus name Gastonia honors Robert Gaston, the paleo-artist and CEO of Gaston Design Inc. who discovered the first fossils in 1989; species name burgei honors Donald L. Burge, then director of the College of Eastern Utah Prehistoric Museum (now USU Eastern Prehistoric Museum)"

Local Name: Gastonia

🕐Cretaceous Period

🌿Herbivore

Physical Characteristics

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Size4.59~6m

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Weight1900kg

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Height1.12m

Discovery

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Discovery Year1998Year

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DiscovererJames I. Kirkland

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Discovery LocationGrand County, eastern Utah, USA (Cedar Mountain Formation — Yellow Cat Member: Gaston Quarry, Dalton Wells; Poison Strip Member: Lorrie's Site)

Habitat

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Geological FormationCedar Mountain Formation (Yellow Cat Member, Poison Strip Member)

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EnvironmentSemi-arid floodplain with seasonal wet-dry cycles — partly wooded habitat with riverine forests separated by open areas (Vertisol-like paleosols with prominent slickensides, carbonate nodules, and crack fills documented; Joeckel et al., 2017; 2023)

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LithologyMudstone (dominant, with prominent paleosol development), limestone (palustrine to lacustrine carbonate nodules/calcrete), sandstone (fluvial channel deposits)

Gastonia (Kirkland, 1998) is a medium-sized ankylosaurian dinosaur from the Early Cretaceous (approximately 139–125.77 Ma) of North America. It is generally classified within the Nodosauridae, subfamily Polacanthinae, and is considered closely related to the contemporaneous European genus Polacanthus. The holotype specimen of the type species G. burgei (CEUM 1307) was discovered in a bonebed within interbedded limestone and siltstone strata of the Yellow Cat Member of the Cedar Mountain Formation at Gaston Quarry, Grand County, eastern Utah, and consists of a single adult skull (Kirkland, 1998). A second species, G. lorriemcwhinneyae Kinneer et al., 2016, is known from the Poison Strip Member of the same formation.

Gastonia is among the most abundant ankylosaurians in the Early Cretaceous of North America, with numerous specimens recovered from multiple quarries including Gaston Quarry, Dalton Wells, and Lorrie's Site. More complete material exists for Gastonia than for any other basal ankylosaur (Benton, 2012). Size estimates vary by study: Kirkland (1998) estimated the total length at approximately 6 m, while Paul (2010) estimated approximately 5 m with a body mass of about 1.9 tonnes. A mounted skeleton composite at the Denver Museum of Nature and Science measures 4.59 m in length with a hip height of 1.12 m (Gaston et al., 2001). Gastonia is characterized by large, flat triangular spikes along its flanks and a fused pelvic shield (sacral shield), but notably lacks the tail club found in derived ankylosaurids such as Ankylosaurus. Together with Gargoyleosaurus, it was the first basal ankylosaurian to be mounted for museum display (Gaston et al., 2001).

Overview

Name and Etymology

The genus name Gastonia honors Robert Gaston, an American paleo-artist and CEO of Gaston Design Inc. who discovered the first fossils in 1989 at a hillside north of Arches National Park in eastern Utah (Kirkland, 1998). The name appeared informally in various publications and popular media throughout the mid-1990s — including Robert Bakker's novel Raptor Red (1996) and the TV series Paleoworld — but was not formally described until 1998. The name Gastonia burgei first appeared in a professional scientific paper by Carpenter & Kirkland (1998) in a review of North American ankylosaurs, with the formal description published by Kirkland (1998) in the same journal issue. The species name burgei honors Donald L. Burge, then director of the College of Eastern Utah Prehistoric Museum (now USU Eastern Prehistoric Museum).

Taxonomic Status

Gastonia belongs to Ornithischia, Thyreophora, Ankylosauria. In his original description, Kirkland (1998) placed Gastonia within the Ankylosauridae, specifically the subfamily Polacanthinae. Polacanthines were subsequently often reinterpreted as belonging to the Nodosauridae. However, Arbour (2014) recovered Gastonia as a non-polacanthine basal member of the Ankylosauridae in her comprehensive phylogenetic analysis. Rivera-Sylva et al. (2018) and Madzia et al. (2021) placed it at the base of Nodosauridae.

Two species are currently recognized. The type species G. burgei Kirkland, 1998 is from the Yellow Cat Member (Valanginian, approximately 139–134.6 Ma). G. lorriemcwhinneyae Kinneer et al., 2016 is from the Poison Strip Member (Hauterivian–Barremian) and differs from G. burgei in having a flat skull roof, shorter and proportionally less distally expanded paroccipital processes, a postacetabular process that is only 36% the length of the preacetabular process (compared to 56% in G. burgei), and an ischium with a smoothly curved ventromedial edge without a kink at its midpoint (Kinneer et al., 2016).

One-Line Summary

Gastonia is a polacanthine ankylosaur characterized by large triangular flank spikes and a fused pelvic shield, and represents one of the most iconic armored dinosaurs of the Early Cretaceous of North America.

Gastonia

Cretaceous Period Herbivore Creature Type

Gastonia burgei

Local Name: Gastonia

Overview

Name and Etymology

Taxonomic Status

One-Line Summary

Age, Stratigraphy, and Depositional Environment

Age Range

Gastonia spans the Early Cretaceous, approximately 139–125.77 Ma. The type locality of G. burgei in the Yellow Cat Member was originally assigned a Barremian age (~126 Ma), but recent geochronological and carbon-isotope stratigraphic work by Joeckel et al. (2023) has revised this to Berriasian–Valanginian (approximately 139–134.6 Ma). Their study obtained a high-precision CA-ID-TIMS U-Pb eruption age of 135.10 ± 0.30 Ma from zircons extracted from a paleosol cryptotephra at the Utahraptor Ridge section. Carbon-isotope features on the chemostratigraphic profile are tentatively interpreted as the Valanginian double-peak carbon isotope excursion (the "Weissert Event") and some unnamed Berriasian features, supporting the interpretation that the Yellow Cat Member records a significant portion of earliest Cretaceous time. G. lorriemcwhinneyae is from the overlying Poison Strip Member, assigned to the Hauterivian–Barremian (Kirkland et al., 2025).

Formation and Lithology

Gastonia fossils are found exclusively in the Cedar Mountain Formation, a non-marine sedimentary unit in eastern Utah that lies above the Morrison Formation and below the Naturita Formation. The formation records fluvial, lacustrine, and floodplain depositional settings.

The holotype of G. burgei (CEUM 1307) was recovered from a bonebed within interbedded limestone and siltstone in the upper Yellow Cat Member at Gaston Quarry (Kirkland, 1998). The Yellow Cat Member is dominated by light greenish-gray to red alluvial mudstones with prominently developed paleosols, with palustrine to lacustrine carbonate nodules ("calcretes") and subordinate fluvial sandstones (Joeckel et al., 2017; 2023). Additional G. burgei specimens were recovered from Dalton Wells, approximately 20 km northwest of Moab, where a debris-flow-hosted bonebed yielded thousands of fossil specimens (Eberth et al., 2006; Britt et al., 2009). G. lorriemcwhinneyae was initially reported from the lower Ruby Ranch Member (Kinneer et al., 2016) but later corrected to the Poison Strip Member (Kirkland et al., 2025).

Depositional Environment and Paleoclimate

The Yellow Cat Member records alluvial mudstone-dominated deposition with stacked paleosols. Joeckel et al. (2017; 2023) documented Vertisol-like paleosol features including prominent slickensides reflecting shrink-swell behavior of expansive clays during seasonal wet-dry cycles, carbonate-filled cracks, and evidence of vertical translocation of soil materials through pedoturbation. These features indicate a semi-arid climate with pronounced seasonal wet-dry alternation.

According to Paul (2010), Gastonia inhabited a partly wooded environment with riverine forests separated by open areas under a rather dry climate with short wet seasons. The Cedar Mountain Formation as a whole records a general trend from arid to semi-arid conditions in the lower members toward progressively more humid conditions upsection.

Specimens and Diagnostic Characters

Holotype and Key Specimens

The holotype of G. burgei (CEUM 1307, housed at USU Eastern Prehistoric Museum, Price, Utah) is a single adult skull. It was the largest of five braincases found at Gaston Quarry, with fused bones indicating adult status; the remaining individuals were determined to be sub-adults (Kirkland, 1998). Four partial skeletons were designated as paratypes, recovered from the same bonebed alongside the type specimen of Utahraptor and iguanodontid remains. A total of 4–6 Gastonia individuals were identified from Gaston Quarry. The number of known skulls rose from 4 in 2004 (Vickaryous et al., 2004) to 10 by 2014 (Kirkland, 2014).

Substantial additional material was recovered from Dalton Wells. Britt et al. (2009) reported 590 osteoderms and 316 skeletal elements attributable to Gastonia, representing a minimum of 9 individuals (1 adult and 8 sub-adults). The Dalton Wells quarry covers approximately 4,000 m² but only about 4.5% of this area has been excavated, suggesting significant potential for further discoveries.

The holotype of G. lorriemcwhinneyae (DMNH 49877, Denver Museum of Nature and Science) is a skull roof, recovered from a large bonebed at Lorrie's Site in Grand County, Utah, discovered by Lorrie McWhinney in 1999 (Kinneer et al., 2016). The bonebed measures approximately 8,600 m² in area and 30 cm in thickness. As of 2021, at least 12 individuals of G. lorriemcwhinneyae are known. The mass mortality assemblage suggests death by drought or drowning.

Altogether, as of 2009, at least 15 individuals of G. burgei alone (6 from Gaston Quarry + 9 from Dalton Wells) have been identified, making Gastonia the best-known basal ankylosaur in terms of skeletal completeness (Benton, 2012). However, most material was found disarticulated, making precise reconstruction of individual spike counts and arrangements challenging.

Diagnostic Characters

Kirkland (1998) identified three autapomorphies unique within Ankylosauria as a whole. First, a broad, gradually curved notch is present on the midline of the snout between the premaxillae. Second, the bony nostrils are positioned unusually far posteriorly. Third, the basipterygoid processes of the basisphenoid are longitudinally elongated.

G. lorriemcwhinneyae is distinguished from G. burgei by a flat skull roof (versus convex), shorter and less distally expanded paroccipital processes, a postacetabular process only 36% the length of the preacetabular process (versus 56%), and an ischium with a smooth ventromedial contour lacking the midpoint kink seen in G. burgei (Kinneer et al., 2016).

Specimen Limitations

Most Gastonia fossils were recovered in a disarticulated state, making it difficult to determine the precise number and arrangement of spikes for any individual specimen (Benton, 2012). The mounted skeleton at the Denver Museum of Nature and Science was assembled from polyurethane casts of multiple individuals, with fossil distortions corrected and missing elements restored (Gaston et al., 2001). Accordingly, some aspects of the mounted reconstruction are hypothetical. Recent paleoart research has also suggested that the spike sizes depicted in earlier popular reconstructions may have been significantly exaggerated compared to actual measured specimens.

Morphology and Function

Body Shape and Size

Gastonia was a medium-sized ankylosaur. Size estimates vary: Kirkland (1998) estimated total length at approximately 6 m (20 ft), Paul (2010) at approximately 5 m (16 ft) with a body mass of about 1.9 t (4,200 lb), and the mounted composite skeleton measures 4.59 m in length with a hip height of 1.12 m (Gaston et al., 2001). The mount is a composite of multiple individuals and may not represent any single individual precisely.

Gastonia had a notably flat and very broad rump, even for an ankylosaurian, with a strongly protruding belly between short, powerful limbs. The tail was moderately long and lacked both a tail club and stiffened distal caudal vertebrae. The neck was relatively long and the skull was comparatively small.

Skull and Dentition

The skull is somewhat elongated and pointed, subtriangular in dorsal view, measuring 295 by 283 mm in the holotype. The dorsal profile is convex, with the rear skull roof curving below the level of the upper rim of the eye sockets. The quadrate is very strongly inclined posteriorly. The occipital condyle points obliquely ventrally, an ankylosaurid trait causing the head to be directed downward.

The beak is edentulous. The maxillary tooth rows are rather straight, each consisting of 15–16 small teeth lacking a true cingulum. The snout lacks armor (caputegulae), while the skull roof's bony tiles become less distinctly patterned posteriorly, though a small central plate on the parietal bones is visible. The squamosal horns and jugal horns are small (Kirkland, 1998).

Limbs and Postcranial Skeleton

The sacrum consists of 3 sacral vertebrae with a caudosacral vertebra behind them — contrasting with the 4 sacrals in Polacanthus. The scapula possesses a blade-like acromion resembling that of nodosaurids, but it originates from the anterior edge of the scapula (rather than the lateral surface) and does not wrap posteriorly or terminate in a knob, differing from the typical nodosaurid "pseudoacromion." The coracoid is square, a characteristic ankylosaurid trait. The humerus bears a large deltopectoral crest extending to mid-shaft, a derived condition. The ulna is very robust with an enormous olecranon. The tibia is strongly expanded at both proximal and distal ends (Kirkland, 1998).

Armor (Osteoderms and Spikes)

Gastonia was protected by extensive dermal armor. The neck was covered by at least 2–3 bone rings. Unlike the typical half-rings of other ankylosaurs, Gastonia's cervical armor appears to have had only two segments per ring (one on each side of the midline), leading Kirkland to coin the term "quarter rings." Each segment bore a pointed keel with a hollow underside.

The trunk armor reconstruction is challenging because it was not found in articulation. According to Kirkland (1998), approximately 5 pairs of large, flat, triangular spikes covered the sides of the thorax. These spikes are recurved and bear deep grooves on their posterior surfaces, interpreted as receiving the anterior edge of the succeeding spike. They gradually decrease in size posteriorly, with the groove becoming relatively shorter and the base length increasing. Other large flat spikes lacking grooves were found, often strongly curved with the point at right angles to the base; Kirkland interpreted these as forming two vertical rows flanking the rump midline. Smaller triangular spikes were placed along the sides of the tail, again decreasing posteriorly. The tail had good lateral flexibility but limited dorsoventral movement. Between the horizontal and vertical spike rows, droplet-shaped osteoderms (with a vertical point at the broader end) were likely present. The dorsal tail surface bore oval plates.

The lateral spikes are hollow-based while the dorsal osteoderms are solid-based (Kirkland, 1998; Arbour et al., 2011). The hip region was covered by a large pelvic shield consisting of fused osteoderms arranged in rosette patterns — a large central plate surrounded by at least two rings of smaller plates. Kirkland (1998) proposed that 4 pairs of triangular spikes also covered the sides of the pelvic shield, but Paul (2010) disputed this. The spaces between all larger armor elements were filled by hundreds of small round ossicles up to 2 cm in diameter (Kirkland, 1998).

Compared to Polacanthus, Gastonia's triangular spikes are larger, and the tail spikes are less recurved.

Defense and Intraspecific Competition

Kirkland (1998) proposed that Gastonia's armor was an effective defense against the apex predator of its habitat, the giant dromaeosaurid Utahraptor, remains of which were found in the same quarry. The typical polacanthine defensive strategy would have combined passive protection from vertical spikes with active defense by swinging the flexible tail's horizontal spikes at attackers. The armor may also have served in intraspecific combat. Kirkland noted that Gastonia's somewhat domed skull roof resembles that of dinocephalian synapsids thought to have engaged in head-pushing contests, and that the slightly flexible braincase may have functioned as a shock absorber. The typical ankylosaurid downward-facing head posture (enabled by a more ventrally directed occipital condyle) and increased loosening of posterior skull elements were proposed as adaptations to such head-pushing behavior.

Fun Facts

Locality	Member	Species	Discovery Year	Minimum Individuals
Gaston Quarry (Yellow Cat Quarry)	Yellow Cat	G. burgei	1989–1992	4–6
Dalton Wells	Yellow Cat	G. burgei	1975–1994+	at least 9
Lorrie's Site	Poison Strip	G. lorriemcwhinneyae	1999	at least 12

Study	Position of Gastonia	Method/Dataset
Kirkland, 1998	Ankylosauridae, Polacanthinae	Original description
Arbour, 2014	Non-polacanthine basal Ankylosauridae	Comprehensive phylogenetic analysis (Ph.D. thesis)
Rivera-Sylva et al., 2018; Madzia et al., 2021	Basal Nodosauridae	Morphological cladistic analysis
Raven et al., 2023	Nodosauridae potentially polyphyletic	Large-scale thyreophoran phylogeny

Taxon	Age	Region	Size	Key Features
Gastonia	Early Cretaceous (Berriasian–Barremian)	North America (Utah)	~4.6–6 m, ~1.9 t	Large triangular spikes, pelvic shield, no tail club, 3 sacrals
Polacanthus	Early Cretaceous (Barremian–Aptian)	Europe (England)	~5 m	Lateral spikes, pelvic shield, no tail club, 4 sacrals
Hoplitosaurus	Early Cretaceous	North America (South Dakota)	Unknown (fragmentary)	Incomplete, resembles Polacanthus
Gargoyleosaurus	Late Jurassic (Kimmeridgian)	North America (Wyoming)	~3 m	Basal ankylosaur, spikes and plates
Mymoorapelta	Late Jurassic	North America (Colorado)	~3 m	Basal ankylosaur
Ankylosaurus	Late Cretaceous (Maastrichtian)	North America	~6–8 m	Tail club present, derived Ankylosauridae

Specimen Number	Species	Elements	Locality	Formation/Member	Reference
CEUM 1307 (holotype)	G. burgei	1 adult skull	Gaston Quarry, Grand Co., Utah	Cedar Mountain Fm., Yellow Cat Mb.	Kirkland, 1998
4 paratypes	G. burgei	Partial skeletons	Gaston Quarry	Cedar Mountain Fm., Yellow Cat Mb.	Kirkland, 1998
Multiple (min. 9 individuals)	G. burgei	590 osteoderms + 316 skeletal elements	Dalton Wells, Grand Co., Utah	Cedar Mountain Fm., Yellow Cat Mb.	Britt et al., 2009
DMNH 49877 (holotype)	G. lorriemcwhinneyae	Skull roof	Lorrie's Site, Grand Co., Utah	Cedar Mountain Fm., Poison Strip Mb.	Kinneer et al., 2016
Multiple paratypes (min. 12 individuals)	G. lorriemcwhinneyae	Various skeletal elements	Lorrie's Site	Cedar Mountain Fm., Poison Strip Mb.	Kinneer et al., 2016

Study	Estimated Length	Estimated Mass	Method/Notes
Kirkland, 1998	~6 m	Not provided	Original description
Paul, 2010	~5 m	~1.9 t	Volumetric estimate
Mounted skeleton (Gaston et al., 2001)	4.59 m	Not provided	Multi-individual cast composite; hip height 1.12 m

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Gastonia is the best-known basal ankylosaur in terms of skeletal completeness (Benton, 2012). As of 2009, at least 15 individuals of G. burgei alone (6 from Gaston Quarry + 9 from Dalton Wells) had been identified.

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The type specimens of both Gastonia and Utahraptor were found in the same quarry (Gaston Quarry), suggesting a predator-prey relationship between the giant raptor and the armored ankylosaur (Kirkland, 1998).

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In the late 1990s, the Denver Museum of Nature and Science mounted a Gastonia skeleton composite, making it — together with Gargoyleosaurus — the first basal ankylosaurian ever displayed in a museum (Gaston et al., 2001).

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The G. lorriemcwhinneyae bonebed at Lorrie's Site covers approximately 8,600 square meters and contains at least 12 individuals, possibly representing a herd killed simultaneously by drought or flooding (Kinneer et al., 2016).

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Some of Gastonia's lateral spikes bear deep grooves on their posterior surfaces, which Kirkland (1998) interpreted as interlocking mechanisms where each spike's groove received the anterior edge of the next spike.

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Although ankylosaurs were long assumed to be solitary animals due to their short legs, the mass-mortality assemblages of Gastonia — particularly the 1 adult + 8 sub-adults at Dalton Wells — challenge this assumption (Vickaryous et al., 2004; Britt et al., 2009).

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The similarities between Gastonia and England's Polacanthus, along with the presence of European-derived turiasaurian sauropods (Mierasaurus, Moabosaurus) and the haramiyid mammaliaform Cifelliodon, suggest trans-Atlantic faunal exchange persisted well into the Early Cretaceous.

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The age of the Yellow Cat Member was recently revised by approximately 10 million years — from Barremian (~126 Ma) to Berriasian–Valanginian (~139–134.6 Ma) — based on high-precision U-Pb dating (Joeckel et al., 2023).

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Gastonia's neck armor consists of unusual "quarter rings" (only 2 segments per ring) rather than the typical ankylosaur "half rings," a term coined specifically by Kirkland for this unique arrangement.

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The Dalton Wells quarry covers about 4,000 square meters but only approximately 4.5% has been excavated, yielding over 5,000 fossils including hundreds of Gastonia elements — suggesting enormous potential for future discoveries (Britt et al., 2009).

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The name "Gastonia" appeared informally in popular media throughout the mid-1990s — including Robert Bakker's novel Raptor Red (1996) and the TV series Paleoworld — before its formal scientific description was published in 1998.

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At Doelling's Bowl in the lower Yellow Cat Member, remains of an unnamed polacanthine ankylosaur (informally called "Polacanthine A" or "Gamera") estimated at twice the size of Gastonia (~9–11 m) have been reported (Kirkland et al., 2016).

FAQ

?What does the name Gastonia mean?

The genus name "Gastonia" honors Robert Gaston, an American paleo-artist and CEO of Gaston Design Inc. who discovered the first fossils in eastern Utah in 1989. The species name "burgei" honors Donald L. Burge, then director of the College of Eastern Utah Prehistoric Museum (now USU Eastern Prehistoric Museum) (Kirkland, 1998).

?How big was Gastonia?

Size estimates vary by study. Kirkland (1998) estimated approximately 6 m (20 ft) in length, while Paul (2010) estimated approximately 5 m (16 ft) with a body mass of about 1.9 tonnes (4,200 lb). A mounted composite skeleton at the Denver Museum of Nature and Science measures 4.59 m in length with a hip height of 1.12 m (Gaston et al., 2001). These differences reflect individual size variation and differing reconstruction methods.

?Did Gastonia have a tail club?

No. Gastonia is a polacanthine ankylosaur and lacked both the bony tail club and the stiffened distal caudal vertebrae found in derived ankylosaurids such as *Ankylosaurus*. Instead, the sides of its tail were lined with triangular spikes that may have been used defensively by swinging the flexible tail (Kirkland, 1998).

?What were Gastonia's spikes used for?

According to Kirkland (1998), the large triangular flank spikes and pelvic shield served as effective defense against the apex predator of its habitat, the giant dromaeosaurid *Utahraptor*. The vertical spikes provided passive protection, while the horizontal tail spikes allowed active defense. The armor may also have functioned in intraspecific combat, with males potentially engaging in head-pushing contests — an interpretation supported by the somewhat domed skull and slightly flexible braincase.

?Did Gastonia live in herds?

Ankylosaurs have traditionally been assumed to be solitary, but the concentration of Gastonia fossils suggests at least some gregarious behavior. At Gaston Quarry, 4–6 individuals were found together; at Dalton Wells, at least 9 individuals (1 adult, 8 sub-adults) were recovered; and at Lorrie's Site, at least 12 individuals of *G. lorriemcwhinneyae* were discovered in a single bonebed, probably resulting from mass mortality during drought or flooding (Britt et al., 2009; Kinneer et al., 2016).

?Did Gastonia and Utahraptor live at the same time?

Yes. The type specimens of both *Gastonia* and *Utahraptor* were found in the same quarry (Gaston Quarry in the Yellow Cat Member, Cedar Mountain Formation), confirming their co-occurrence (Kirkland, 1998). *Utahraptor* was the apex predator of this ecosystem, and Gastonia's extensive armor may have evolved partly as a defense against it.

?How many species of Gastonia are there?

Two species are currently recognized. The type species *G. burgei* Kirkland, 1998 (holotype: CEUM 1307) is from the Yellow Cat Member, and *G. lorriemcwhinneyae* Kinneer et al., 2016 (holotype: DMNH 49877) is from the Poison Strip Member. They differ in skull roof shape, paroccipital process proportions, pelvic structure, and ischium morphology. Additionally, an unnamed large polacanthine (informally called "Polacanthine A" or "Gamera") has been reported from lower in the Yellow Cat Member at Doelling's Bowl.

?What kind of environment did Gastonia live in?

Gastonia inhabited a semi-arid floodplain with short wet seasons, where riverine forests were separated by open areas (Paul, 2010). Paleosol evidence from the Yellow Cat Member — including Vertisol-like slickensides, carbonate nodules, and crack fills — confirms pronounced seasonal wet-dry cycles (Joeckel et al., 2017; 2023).

?How was the age of the Yellow Cat Member revised?

The Yellow Cat Member was previously assigned to the Barremian (~126 Ma), but Joeckel et al. (2023) obtained a CA-ID-TIMS U-Pb eruption age of 135.10 +/- 0.30 Ma from zircons in a paleosol cryptotephra at Utahraptor Ridge. Combined with carbon-isotope stratigraphy tentatively identifying the Valanginian "Weissert Event," this revised the age to Berriasian–Valanginian (~139–134.6 Ma) — approximately 10 million years older than previously thought.

?How is Gastonia related to Polacanthus?

*Gastonia* and the English *Polacanthus* are closely related polacanthine ankylosaurs sharing similar armor features including a fused pelvic shield and lateral flank spikes. However, they differ in several respects: *Gastonia* has 3 sacral vertebrae (vs. 4 in *Polacanthus*), larger triangular spikes, less recurved tail spikes, and a differently shaped pelvis and femur. Their similarities support the hypothesis of trans-Atlantic faunal exchange between North America and Europe during the Early Cretaceous (Kirkland et al., 1997).

📚References

Kirkland, J.I. (1998). A polacanthine ankylosaur (Ornithischia: Dinosauria) from the Early Cretaceous (Barremian) of eastern Utah. In: S.G. Lucas, J.I. Kirkland, & J.W. Estep (eds), Lower and Middle Cretaceous Terrestrial Ecosystems, New Mexico Museum of Natural History and Science Bulletin 14: 271–281.

Kinneer, B.; Carpenter, K.; Shaw, A. (2016). Redescription of Gastonia burgei (Dinosauria: Ankylosauria, Polacanthidae), and description of a new species. Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen, 282(1): 37–80. doi:10.1127/njgpa/2016/0605.

Paul, G.S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 228.

Gaston, R.W.; Scellenbach, J.; Kirkland, J.I. (2001). Mounted skeleton of the polacanthine ankylosaur Gastonia burgei. In: Carpenter, K. (ed.), The Armored Dinosaurs. Indiana University Press. pp. 386–398. ISBN 0-253-33964-2.

Vickaryous, M.K.; Maryanska, T.; Weishampel, D.B. (2004). Ankylosauria. In: Weishampel, D.B., Dodson, P., Osmolska, H. (eds), The Dinosauria, 2nd ed. University of California Press. pp. 363–392.

Benton, M.J. (2012). Prehistoric Life. Dorling Kindersley. p. 334. ISBN 978-0-7566-9910-9.

Joeckel, R.M.; Suarez, C.A.; McLean, N.M.; Moller, A.; Ludvigson, G.A.; Suarez, M.B.; Kirkland, J.I.; et al. (2023). Berriasian–Valanginian geochronology and carbon-isotope stratigraphy of the Yellow Cat Member, Cedar Mountain Formation, eastern Utah, USA. Geosciences, 13(2): 32. doi:10.3390/geosciences13020032.

Arbour, V.M. (2014). Systematics, evolution, and biogeography of the ankylosaurid dinosaurs. Ph.D thesis, University of Alberta.

Rivera-Sylva, H.E.; Frey, E.; Stinnesbeck, W.; et al. (2018). Paleodiversity of Late Cretaceous Ankylosauria from Mexico and their phylogenetic significance. Swiss Journal of Palaeontology, 137(1): 83–93. doi:10.1007/s13358-018-0153-1.

Madzia, D.; Arbour, V.M.; Boyd, C.A.; et al. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ, 9: e12362. doi:10.7717/peerj.12362.

Kirkland, J.I.; Sertich, J.J.W.; Titus, A.L. (2025). Dinosaur biostratigraphy of the non-marine Cretaceous of Utah. Geological Society, London, Special Publications, 545: 65–90. doi:10.1144/SP545-2023-211.

Kirkland, J.I. (2014). The nature of the Jurassic/Cretaceous (J/K) unconformity and the Early Cretaceous of eastern Utah. In: Mid-Mesozoic: the Age of Dinosaurs in Transition. pp. 62–63.

Joeckel, R.M.; Ludvigson, G.A.; Kirkland, J.I. (2017). Lower Cretaceous paleo-Vertisols and sedimentary interrelationships in stacked alluvial sequences, Utah, USA. Sedimentary Geology, 361: 1–24.

Kirkland, J.I.; Burge, D.; Gaston, R. (1997). A large dromaeosaur (Theropoda) from the Lower Cretaceous of eastern Utah. Hunteria, 2(10): 1–16.

Carpenter, K.; Kirkland, J.I. (1998). Review of Lower and Middle Cretaceous ankylosaurs from North America. In: Lucas, S.G., Kirkland, J.I., Estep, J.W. (eds), Lower and Middle Cretaceous Terrestrial Ecosystems, New Mexico Museum of Natural History and Science Bulletin 14: 249–270.

Britt, B.B.; Eberth, D.A.; Scheetz, R.D.; Greenhalgh, B.W.; Stadtman, K.L. (2009). Taphonomy of debris-flow hosted dinosaur bonebeds at Dalton Wells, Utah (Lower Cretaceous, Cedar Mountain Formation, USA). Palaeogeography, Palaeoclimatology, Palaeoecology, 280: 1–22.

Eberth, D.A.; Britt, B.B.; Scheetz, R.; Stadtman, K.L.; Brinkman, D.B. (2006). Dalton Wells: geology and significance of debris-flow-hosted dinosaur bonebeds in the Cedar Mountain Formation (Lower Cretaceous) of eastern Utah, USA. Palaeogeography, Palaeoclimatology, Palaeoecology, 236: 217–245.

Raven, T.J.; Barrett, P.M.; Sherwin, J. (2023). The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora). Journal of Systematic Palaeontology, 21(1): 2205433. doi:10.1080/14772019.2023.2205433.

Arbour, V.M.; Burns, M.E.; Currie, P.J. (2011). A review of pelvic shield morphology in ankylosaurs (Dinosauria: Ornithischia). Journal of Paleontology, 85(2): 298–302.

Britt, B.B.; Scheetz, R.D.; Whiting, M.F.; Wilhite, D.R. (2017). Moabosaurus utahensis, n. gen., n. sp., a new sauropod from the Early Cretaceous (Aptian) of North America. Contributions from the Museum of Paleontology, University of Michigan, 32(11): 189–243.

Last updated: March 7, 2026

Overview

Name and Etymology

Taxonomic Status

One-Line Summary

Overview

Name and Etymology

Taxonomic Status

One-Line Summary

Age, Stratigraphy, and Depositional Environment

Age Range

Formation and Lithology

Depositional Environment and Paleoclimate

Specimens and Diagnostic Characters

Holotype and Key Specimens

Diagnostic Characters

Specimen Limitations

Morphology and Function

Body Shape and Size

Skull and Dentition

Limbs and Postcranial Skeleton

Armor (Osteoderms and Spikes)

Defense and Intraspecific Competition

Diet and Ecology

Diet

Ecological Role

Social Behavior

Distribution and Paleogeography

Fossil Localities

Paleogeography

Phylogeny and Taxonomic Debate

Phylogenetic Analyses

Alternative Hypotheses and Ongoing Debate

Reconstruction and Uncertainty

Established, Likely, and Hypothetical

Popular Media vs. Scientific Consensus

Comparative Table: Related and Contemporary Taxa

Data Tables

Specimen Summary

Size and Mass Estimates

Fun Facts

FAQ

📚References

Gallery