Spicomellus afer: A surprisingly well-armoured Ankylosaur from the Middle Jurassic of Morocco.

The Ankylosaurs were a group of heavily-armoured, short-limbed, wide-bodied, Ornithischian Dinosaurs, best known from Late Cretaceous deposits in Eurasia and North America. Although the group is known to have existed by the Middle Jurassic, remains from this period are limited to a jawbone and a few teeth from two sites in England, and it has been speculated that earlier members of the group may have lacked the heavy armour of the Late Cretaceous species. This is not unreasonable, the Late Cretaceous saw the emergence of a range of new predators, including novel groups of Theropod Dinosaurs and Crocodilians, and the first large predatory Mammals and Snakes, leading to the evolution of novel defence strategies in many herbivorous groups. 

Although well known from the Laurasian Continents, Ankylosaurs were for a long time thought to be absent from Gondwana. However, in 1986 this was changed by the discovery of Antarctopelta oliveroi, from the Late Cretaceous of Antarctica, the first known Dinosaur from that continent. This was followed in 1989 by the discovery of Kunbarrasaurus ieversi, a small Ankylosaur from the Early Cretaceous of Australia. The subsequent discovery of Stegouros elengassen from the Late Cretaceous of southern Chile and Patagopelta cristata from the Late Cretaceous of Argentina confirmed that Ankylosaurs were present, if uncommon, across Gondwana in the Cretaceous, and it was speculated that these Dinosaurs were members of a single clade, the Parankylosauria, which had split from its Laurasian cousins early in the history of the group, and developed a range of distinctive traits, including a distinctive tail weapon formed from five pairs of robust osteoderms, fused together to form a flat, fan-like weapon called a 'macuahuitl', in reference to a traditional weapon from Mesoamerica, made from a series of obsidian blades mounted on a wooden club, giving a sword-like appearance. 

Spicomellus afer was first described in 2021 from a single rib-fragment with fused spikes from Morocco. The fossil appeared to have clear Ankylosaurian affinities, and, importantly, came from the Middle Jurassic, apparently confirming the hypothesis of an early-branching clade of Ankylosaurs reaching Gondwana and diversifying there.

In a paper published in the journal Nature on 27 August 2025, Susannah Maidment of the Fossil Reptiles, Amphibians and Birds Section a the Natural History Museum, and the School of Geography, Earth and Environmental Sciences at the University of Birmingham, Driss Ouarhache, Kawtar Ech-charay, Ahmed Oussou, Khadija Boumir, and Abdessalam El Khanchou of the GERA Laboratory at Sidi Mohamed Ben Abdellah University, Alison Park of Emanya Fossil Preparation and Conservation, Luke Meade, also of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, Cary Woodruff of the Phillip and Patricia Frost Museum of Science, and the Museum of the Rockies, Simon Wills and Mike Smith, also of the Fossil Reptiles, Amphibians and Birds Section a the Natural History Museum, Paul Barrett, again of the Fossil Reptiles, Amphibians and Birds Section a the Natural History Museum, and of the Evolutionary Studies Institute at the University of the Witwatersrand, and Richard Butler, once again of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, describe a new partial skeleton of Spicomellus afer, enabling a more complete reconstruction of the species and a re-interpretation of the history of the Ankylosauria. 

The new material comprises a left quadrate, two cervical, two dorsal, four sacral and four free caudal vertebrae, two handle vertebrae, six dorsal ribs with spikes fused to their dorsal surfaces, both scapulocoracoids, ilia and pubes, the right ischium, two metatarsals, an elaborate cervical half ring bearing extremely long spikes, a sacral shield bearing small and large spikes, numerous plates, large and small spikes of various morphologies, and several compound osteoderms comprising combinations of small and large spikes. These suggest an unusually well-armoured Animal, even compared to other Ankylosaurs, casting doubt upon the prevailing idea that heavy armour developed in the group in the Late Cretaceous as a result of increased predation pressures. 

A life reconstruction of Spicomellus afer. (a), (b) A life reconstruction of Spicomellus afer  showing hypothetical positions of armour in dorsal (a) and right lateral (b)  views. (c) USMBA 19: a blade-like spine that is 43 cm long. (d) USMBA 70:  a compound osteoderm with large, oval base. The long spike is 35 cm long. (e) USMBA 12: part of the left ilium bearing a fused sacral shield, which includes  a large iliac spike lying dorsal to the acetabulum. The height of the spike, as  preserved, is 24 cm. (f) USMBA 14: cervical half-ring. The length of the longest spike is 87 cm. (g) USMBA 30: a slender, rounded spike that is 10 cm long. (h) USMBA 12: a portion of the left ilium bearing a fused sacral shield ornamented by small, rounded spikes. (i) USMBA 37: a slender, rounded spike that is 30 cm long. (j) USMBA 12: a large spike with a robust, expanded base plate. The spike is 23 cm long. The specimen was found in association with the iliac spike (e). (k) USMBA 26: a plate, probably from the pectoral region based on comparisons  with other Ankylosaurs. The plate is 24 cm in length. (l) USMBA 25: a compound osteoderm with spikes, one of which is broken. The better-preserved spike appears to have been the more slender of the two and is 34.5 cm long. (m) USMBA 17: a blade-like spine with an expanded base that is 27 cm long. (n) USMBA 63: a three-spiked osteoderm with a broken basal plate. The height of the middle spike is 3.5 cm. Matt Dempsey in Maidment et al. (2025).

The deposits from which the skeleton was recovered come from the Bathonian stage, making them between 168.2 and 165.3 million years old, making Spicomellus afer equal in age to the oldest known Ankylosaur fossils, a scattering of isolated from the Bathonian White Limestone of England, and close to the predicted split between the Ankylosauria and the Stegosauria. 

A phylogenetic analysis carried out by Maidment et al. was unable to recover the Parankylosauria as a distinct clade of Gondwanan Ankylosaurs. The Chilean Stegouros elengassen was found to be the sister species to all other Anylosaurs, apparently representing an early-diverging, and otherwise lost, lineage, while other members of the proposed Parankylosauria were scattered throughout the Ankylosauria as a whole, with their formerly apparent similarities being a result of convergent evolution.

A simplified time-calibrated strict reduced consensus tree showing  the putative phylogenetic position of Spicomellus afer. Note that the timescale for the  Middle Jurassic has been expanded so that branching patterns can be clearly  seen. Taxa in grey are from the Northern Hemisphere; those in black are from the  Southern Hemisphere. Green text denotes clades. Abbreviations: Aal, Aalenian; Alb, Albian; Apt, Aptian;  Baj, Bajocian; Barr, Barremian; Bath, Bathonian; Berr, Berriasian; Call, Callovian;  Cam, Campanian; Cen, Cenomanian; Con, Coniacian; Haut, Hauterivian;  Hett, Hettangian; Kimm, Kimmeridgian; Maas, Maastrichtian; Oxf, Oxfordian;  Plien, Pliensbachian; Sant, Santonian; Sine, Sinemurian; Tith, Tithonian;  Toar, Toarcian; Tur, Turonian; Vala, Valanginian. Maidment et al. (2025).

Based upon this, Maidment et al. conclude that heavy and extensive armour first appeared in Ankylosaurs in the Middle Jurassic, and was apparently a defining feature of the group from the outset. The further speculate that this may have been a result of sexual selection rather than predation pressure, something which could drive the rapid development of an anatomy distinct from that of their closest relatives. Under this scenario, the widespread appearance of heavily armoured Ankylosaurs in the Late Cretaceous might represent not the adaptation of a less well armoured group to a high predation environment, but rather the advantageous pre-adaptation of the group to such an environment, enabling the Ankylosaurs to flourish at the expense of less well-armoured rival groups.

Armour of Spicomellus afer. Richard Butler, Kawtar Ech-charay, Ahmed Oussou and Alison Park for scale (and the scale bar on the table is 8 cm long). Maidment et al. (2025).

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Vectipelta barretti: A new species of Ankylosaurian Dinosaur from the Early Cretaceous of the Isle of Wight.

The Ankylosaurs are Ornithischian Dinosaurs noted for their broad body, short limbs and extensive covering of dermal armour on the head, body and tail. They are a diverse group, found on all continents, but reaching their greatest diversity on the continents of the former Laurasian landmass, i.e. North America, Europe, and Asia. They split from their sister group, the Stegosaurs, in the Early or early Middle Jurassic, but appear to have remained a minor component of most ecosystems until the Early Cretaceous, when they underwent a significant radiation, remaining a significant member of the herbevore community until their demise in the End Cretaceous extinction. 

A number of Ankylosaurs have been described from the UK, from the Middle Jurassic onwards, although the group reach their maximum abundance in the UK in the Early Cretaceous Wealden Group of southern England. For a long time, all Ankylosaurs from the Wealden Group were referred to two species, Polacanthus foxii and Hylaeosaurus armatus, but this is now thought likely to hide considerable diversity, as the Wealden Group is thought to cover at least 8 million years of time, including all of the Barremian Stage and part of the Aptian.

Traditionally, all Ankylosaur material from the Isle of Wight was referred to Polacanthus foxii, but a recent study of Ankylosaur diversity within the Wealden Group, led by Thomas Raven of the Fossil Reptiles, Amphibians and Birds Section at the Natural History Museum, has suggested that this name should be restricted to the holotype specimen, NHMUKPV R175, and other specimens should be considered taxonomically uncertain until re-examined. One notable specimen examined in Raven et al.'s study was IWCMS 1996.153, known as the Spearpoint Ankylosaur, which was shown to be particularly different to the Polacanthus foxii holotype, and not likely to be closely related.

In a paper published in the Journal of Systematic Palaeontology on 15 June 2023, Stuart Pond, also of the Fossil Reptiles, Amphibians and Birds Section at the Natural History Museum, Sarah-Jane Strachan of the Department of Earth Sciences at University College London, Thomas Raven (again), Martin Simpson of Lansdowne on the Isle of Wight, Kirsty Morgan of Fayetteville in Arkansas, and Susannah Maidment, again of the Fossil Reptiles, Amphibians and Birds Section at the Natural History Museum, formally describe the Spearpoint Ankylosaur as the holotype of a new species.

The Wessex Group consists of a series of terrestrial, lacustrine, flu-vial and lagoonal deposits which outcrop in the Wessex Sub-basin of the Isle of Wight and the Weald Sub-basin of south-east England. On the Isle of Wight the group comprises two formations, the Wessex Formation, considered Barremian in age, and the Vectis Formation, thought to be late Barremian to early Aptian. The Wessex Formation is a sequence about 180 m thick, consisting of variegated mudstones and interbedded sandstones deposited as river channel, floodplain and point bar deposits by a high-sinuosity river system flowing west to east. The overlying Vectis Formation is thought to have been laid down in a shallow lagoon. The largest exposures of both formations are on the southwestern coast of the Isle of Wight, with smaller exposures at Yaverland on the south-east coast.

The Wessex Formation is thought to have been laid down in a Mediterranean climate, with distinctive dry and wet seasons, the latter associated with periodic flood events in which debris flows including large trees and Dinosaur remains were swept down from the (now lost) highlands from which the river descended, and were deposited on the flood plain. This formation is rich in fossils, producing numerous Plant (particularly Gymnosperms), Invertebrates, trace fossils, and a diverse Vertebrate assemblage, including Bony Fish, Turtles, Crocodilians, Pterosaurs and Dinosaurs.

The Spearpoint Ankylosaur was discovered within the Compton Chine to Steephill Cove Site of Special  Scientific Interest, about 50 m to the west of Chilton Chine. Chines on the Isle of Wight, are gullies which cut into the overlying chalk grassland by seasonal streams, and emerging from the cliffs as waterfalls. These features never erode down to beach level, as the cliffs are eroded backwards by the action of the sea faster than the chines are eroded downwards by the streams, and form a unique environment with their own distinctive flora and fauna, including many rare Plants and Insects.

In November 1993 fossil hunter Gavin Leng found several Ankylosaur vertebrae on beach, which he later donated to the Dinosaur Isle Museum. The following spring another fossil hunter Lin Spearpoint, discovered the remainder of the skeleton in the cliffs above, on land belonging to dairy farmer Richard Fisk. Fisk gave permission for Lin Spearpoint, Dick Spearpoint, and Martin Simpson, to excavate the skeleton, which was then prepared by Lin Spearpoint, housed at the University of Southampton, where it was the subject of several MSci, MRes and PhD projects, some of which were carried out by Stuart Pond, Sarah-Jane Strachan, and Kirsty Morgan, temporarily displayed at the SeaCity  Museum,  Southampton, and eventually acquired by the Dinosaur Isle Museum. 

Pond et al. formally describe the Spearpoint Ankylosaur as the holotype of a new species, Vectipelta barretti, where 'Vectipelta' means 'Vectis-shield' (Vectis was the name used by the Romans for the Isle of Wight), and 'barretti' honours Paul Barrett of the Natural History Museum, in recognition of his major and ongoing contributions to Dinosaurian Vertebrate palaeontology, and his importance to Stuart Pond, Thomas Raven and Susannah Maidment as a mentor, supervisor, colleague and friend.

Geological setting and stratigraphy. (A) Map of Isle of Wight with the extent of Wessex Sub-basin marked in orange, and the site of the Vectipelta barretti (IWCMS 1996.153 and IWCMS 2021.75) excavation indicated by the black arrow. (B) Schematic stratigraphical log of the outcrop between Sudmore Point and Ship Ledge showing the approximate stratigraphical location of Vectipelta barretti (IWCMS 1996.153 and IWCMS 2021.75). Pond et al. (2023).

The new species is described from two specimens, both believed to have come from the same individual and therefore treated as one. WCMS1996.153 comprises portions of four cervical vertebrae and six  free dorsal vertebrae discovered on the foreshore by Gavin Leng in 1993, while IWCMS 2021.75 comprises five fused dorsal vertebrae, forming the sacral rod, fragments of several dorsal ribs, a fused sacrum made up of four and a half fused vertebrae, thirteen caudal vertebrae, and fragments of four more, the proximal part of the left scapula, the proximal and distal ends of the left humerus, a possible ulna fragment, multiple pieces of the iliosacral block, including parts both the left and right ilia, both pubes, fused to the anteromedial margins of the acetabula, a more-or-less complete left ischium, some possible fibula fragments, and second metatarsal, the sacral shield, a large number of osteoderms, and three recurved spines. Specimen IWCMS 2021.75 was found lying on its back, with its (missing) head pointing towards the cliff face, leading to the assumption that the cervical and upper dorsal vertebrae of WCMS1996.153 came from the same individual. Pond et al, note that several years prior to the discovery of WCMS1996.153, a beach-rolled Ankylosaur braincase was found at the same location by fossil hunter David Cooper, and acquired by the University of Cambridge's Sedgwick Museum, and a partial femur and posterior part of an ilium were found nearby by David Richards in the 1990s and donated to the Natural History Museum. These specimens may also relate to the Spearpoint Ankylosaur, but all are heavily eroded, making it impossible to assess them with any confidence, so they were excluded from the study.

Holotype material of Vectipelta barretti, IWCMS 1996.153 and IWCMS 2021.75 in (A) dorsal view; (B) left lateral view; (C) dorsal view of the osteoderms only; (D) complete skeletal reconstruction, in left lateral view. Scale baris 1m. Pond et al. (2023).

The recurved spines of the Spearpoint Ankylosaur are notable, as NHMUKPV R175, the holotype of Polacanthus foxii, lacks any such structure, supporting the idea that the two are quite different Animals. Some spines assigned to Polacanthus sp. have been described from Early Cretaceous of Soria, Spain, but these are also unlikely to derive from that genus. Recurved spines are known in a wide range of Ankylosaurs, including the other Wealden Group species, Hylaeosaurus armatus, but the form of the Spearpoint Ankylosaur's spines is different to any of these, supporting the idea that it should be described as a new species.

Vectipelta barretti, IWCMS 2021.75. Examples of recurved spines. Orientation presumed: (A)–(C) proximal; (D)–(F) distal; (G)–(I) left lateral; (J)–(L) right lateral; (M)–(O) anterior; (P)–(R) posterior. Scale bar is 10 cm. Pond et al. (2023).

Understanding the diversity of Early Cretaceous Ankylosaurs is not just important because we are interested in Dinosaurs; it has implications for our understanding of Mesozoic ecosystems and geology as a whole. The Jurassic is believed to have ended with a mass extinction event, although the nature of this is poorly understood. Terrestrial deposits with good fossil preservation are rare from the Early Cretaceous, leading to the apparent emergence of a quite new ecosystem in the Middle Cretaceous. However, the clustering of multiple specimens from diverse groups under a few poorly constrained species names in Early Cretaceous deposits, as has happened with Wealden Ankylosaurs (and, it has also been suggested, Iguanodontids), could be hiding a more gradual faunal turnover during this interval.

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