''Titanokorys'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of extinct

hurdiid Hurdiidae (synonymous with the previously named Peytoiidae) is an extinct cosmopolitan distribution, cosmopolitan Family (biology), family of radiodonts, a group of Crown group#Stem groups, stem-group marine arthropods, which lived during the Pal ...

(peytoiid)

radiodont Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and were used for a variety ...

(a grouping of primitive

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s which lived during the early

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

) that lived during the

Miaolingian The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about to million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is prec ...

epoch of the middle

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

. It is the largest member of its family from the Cambrian, with an estimated body length of around long, making it one of the largest animals of the time. It bears a resemblance to the related, and contemporary, genus ''

Cambroraster ''Cambroraster'' is an extinct monotypic genus of hurdiid radiodont, dating to the middle Cambrian, and represented by the single formally described species ''Cambroraster falcatus''. Hundreds of specimens were found in the Burgess Shale, and ...

''. Fossils of ''T. gainesi'' were first found within the Marble Canyon locality of the

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fos ...

in 2018, however the fossils were not named until 2021 because they were assumed to be giant specimens of ''Cambroraster''. The taxon is one of several genera of radiodonts known from the Burgess Shale, with some of the others being ''Cambroraster'', ''

Anomalocaris ''Anomalocaris'' (from Ancient Greek , meaning "unlike", and , meaning "shrimp", with the intended meaning "unlike other shrimp") is an extinct genus of radiodont, an order of early-diverging stem-group marine arthropods. It is best known fro ...

'', ''

Peytoia ''Peytoia'' is a genus of hurdiid radiodont, an early diverging order of stem-group arthropods, that lived in the Cambrian period, containing two species, ''Peytoia nathorsti'' from the Miaolingian of Canada and '' Peytoia infercambriensis'' fr ...

'', and ''

Hurdia ''Hurdia'' is an extinct genus of Hurdiidae, hurdiid radiodont that lived 505 million years ago during the Cambrian Period. Fossils have been found in North America, China, and the Czech Republic. Taxonomic history ''Hurdia'' was named in 1912 ...

''. ''Titanokorys'' is distinguished from other Burgess Shale radiodonts because of its large anterior

sclerite A sclerite (Greek language, Greek , ', meaning "hardness, hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instea ...

(head covering carapace, or H-element) and a pair of spines on the anteroventral sides. Based on the shape of its appendages, ''Titanokorys'' is speculated to have used them to sift through the sand looking for prey. It is believed to have fed by using its anterior sclerite to scoop up

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s from the

sea floor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

. Then it would use the endites on its frontal appendages (long grasping structures that all radiodonts possessed) to trap the prey item so it could start consuming it. Because of its size, ''Titanokorys'' was one of the dominant predators of the Burgess Shale and one of the largest animals in its

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

. However, it is a relatively rare faunal component, suggesting that the Burgess Shale represented the edge of this radiodonts geographic range.

Etymology and history of research

The genus name refers to the Titans of

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

in combination with the ancient Greek ''κόρυς'' (''korys'' = "helmet") and alludes to the unusual size of the central carapace element. The species name "gainesi" honors the American

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

Robert R. Gaines, who was instrumental in the discovery of new fossil deposits in the

in 2012. The first description of the genus and type species was made in 2021 by Jean-Bernard Caron and Joseph Moysiuk. This study was based on twelve specimens that came from the Marble Canyon area of Tokumm Creek in the northern part of

Kootenay National Park Kootenay National Park is a national park of Canada in southeastern British Columbia. The park consists of of the Canadian Rockies, including parts of the Kootenay and Park mountain ranges, the Kootenay River and the entirety of the Vermili ...

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

. All previously known specimens are kept at the

Royal Ontario Museum The Royal Ontario Museum (ROM) is a museum of art, world culture and natural history in Toronto, Ontario, Canada. It is one of the largest museums in North America and the largest in Canada. It attracts more than one million visitors every year ...

(ROM) in the Department of Invertebrate Paleontology (ROMIP). Before the animal was named, researchers often nicknamed it the "

mothership A mother ship, mothership or mother-ship is a large vehicle that leads, serves, or carries other smaller vehicles. A mother ship may be a maritime ship, aircraft, or spacecraft. Examples include bomber aircraft, bombers converted to carry exp ...

" or " spaceship" in reference to its massive frontal sclerite (H-element) resembling a starship.

Description

Fossils of ''Titanokorys'' are known from the Burgess Shale, a famous

Lagerstätte A Fossil-Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that preserves an exceptionally high amount of palaeontological information. ''Konzentrat-Lagerstätten'' preserv ...

from

dating to around 508 million years ago. Only disarticulated head

s, frontal appendages and oral cone (radiodont mouthpart that somewhat resembled a camera aperture) have been discovered. Due to the limited discovery, little is known about the oral cone of ''Titanokorys'', but the tooth plates have smooth surfaces like most other hurdiids. Based on the largest sclerite (measured about ) and ratio inferred from the closely related ''Cambroraster'', the complete animal was estimated to be about long. ''Titanokorys'' is readily dintinguised from other radiodonts by the frontal sclerite with a trifurcate anterior region and lateral sclerites ( P-elements). The frontal appendages are almost indistinguishable from those of ''Cambroraster, w''hich have short podomeres with 5 long endites, each associated with a row of long, densely-packed auxiliary spines. These appendages suggest a specialized “ sweep feeding” behaviour that would allow the radiodont to catch and eat both

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale betwe ...

and

macroscopic The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It is the opposite of microscopic. Overview When applied to physical phenome ...

food. ''Titanokorys'' lived alongside other Burgess Shale radiodonts, such as ''

'', ''

'', and ''

''. The fact that so many large

predatory Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

radiodonts lived together suggests that Cambrian

communities A community is a Level of analysis, social unit (a group of people) with a shared socially-significant characteristic, such as place (geography), place, set of Norm (social), norms, culture, religion, values, Convention (norm), customs, or Ide ...

at the time were very diverse and could hold many large macro-predators.

Comparison to ''Cambroraster''

File:20210516 Radiodonta head sclerites Cambroraster falcatus.png, Head sclerite of ''C. falcatus'' File:20210909 Radiodonta head sclerites Titanokorys gainesi.png, Head sclerite of ''T. gainesi'' File:20191229 Radiodonta frontal appendage Cambroraster falcatus.png, The grasping appendage of ''C. falcatus'' File:20210909 Radiodonta frontal appendage Titanokorys gainesi.png, The grasping appendage of ''T. gainesi'' File:Video animation of Cambroraster.webm, A video reconstruction of ''C. falcatus'' File:Titanokorys reconstruction video.webm, A video of a hypothetical reconstruction of ''T. gainesi'' based on ''Cambroraster'' Living alongside ''Titanokorys'' was a similar-looking hurdiid radiodont called ''Cambroraster''. This closely related genus is so similar to ''Titanokorys'' that the latter was originally thought to have been a giant specimen of the former genus and not a distinct taxon. The main difference between them is size, with ''Cambroraster'' reaching in length, while ''Titanokorys'' possibly reached a length of around . Another difference is the shape of the sclerite, with ''Cambroraster'' having a

horseshoe A horseshoe is a product designed to protect a horse hoof from wear. Shoes are attached on the palmar surface (ground side) of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toenail, altho ...

shaped sclerite that was in width for the largest specimen. On the other hand, Titanokorys had a more pointed, larger head sclerite which reached in length. The grasping appendages of the two genera are almost identical, though the secondary spines on the appendages of ''Titanokorys'' are longer than, and possibly not terminally hooked, as the ones seen in ''Cambroraster''.

Classification

''Titanokorys'' is a radiodont belonging to the family

Hurdiidae Hurdiidae (synonymous with the previously named Peytoiidae) is an extinct cosmopolitan distribution, cosmopolitan Family (biology), family of radiodonts, a group of Crown group#Stem groups, stem-group marine arthropods, which lived during the Pal ...

. Hurdiids can be distinguished from other radiodonts by the rake-like frontal appendages which each bore a single row of elongated

endite The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, : ...

s with only anterior auxiliary spines, alongside the combination of enlarged head sclerites and tetraradial mouthparts (oral cone). ''Titanokorys'' was found to form a derived

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

with '' Cordaticaris'', ''

'' and possibly also '' Zhenghecaris''. While '' Stanleycaris'' and ''

Schinderhannes Johannes Bückler ( 177821 November 1803; ) was a German outlaw who orchestrated one of the most famous crime sprees in German history. He has been nicknamed Schinderhannes and Schinnerhannes () in German and John the Scorcher, John the Flayer ...

'' were found as the most basal hurdiids.Phylogenetic placement of ''Titanokorys'', preformed by Moysiuk and Caron (2025).

Ecology

Like many other hurdiid radiodonts, ''Titanokorys'' was most likely a nektobenthic animal that swam slowly above the seabed and sifted through sediments. It is presumed that the animal dug up the sediment with its huge protruding carapace and guided the prey into its mouth, with the frontal appendages forming a cage-like structure. Since fossils may be preserved together alongside ''Cambroraster'', it is presumed that ''Titanokorys'' lived in the same areas as ''Cambroraster''. ''Titanokorys'' is a relatively rare find at Marble Canyon, because of this it is thought that this fossil site possibly occurred near the edge of the species range in life. Due to the depth of the Marble canyon site In comparison to the Cathedral Escarpment, ''Titanokorys'', and the contemporary fauna most likely inhabited a

mesopelagic The mesopelagic zone (Greek language, Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light ...

environment. Recent studies have also found evidence of brine pools in the area, suggesting that these formations would've been present in some areas of the

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

environment. Based on differences in size, ''Titanokorys'' probably escaped competition with ''Cambroraster'' by hunting larger prey, thereby exploiting a different

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

s. Aside from ''Cambroraster'', other creatures lived alongside ''T. gainesi''. The

fauna Fauna (: faunae or faunas) is all of the animal life present in a particular region or time. The corresponding terms for plants and fungi are ''flora'' and '' funga'', respectively. Flora, fauna, funga and other forms of life are collectively ...

in the region included the basal hurdiid ''

Mosura fentoni ''Mosura fentoni'' () is an extinct species of hurdiid radiodont from the Cambrian Burgess Shale in British Columbia, Canada. ''F. fentoni'' is the monotypic taxon, only species in the genus ''Mosura'', and is known from sixty specimens collecte ...

'', hymenocarine arthropods such as '' Tokummia'' and '' Balhuticaris'', the primitive

chordate A chordate ( ) is a bilaterian animal belonging to the phylum Chordata ( ). All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics ( synapomorphies) that distinguish them from ot ...

Metaspriggina ''Metaspriggina'' is a genus of chordate initially known from two specimens in the Middle Cambrian Burgess Shale and 44 specimens found in 2012 at the Marble Canyon bed in Kootenay National Park. Whilst named after the Ediacaran organi ...

'', and the isoxyid arthropod ''

Surusicaris ''Surusicaris'' is an extinct genus of bivalved arthropod, known from the Cambrian Burgess Shale of British Columbia, Canada. It is considered to be closely related to ''Isoxys,'' and like it has spined grasping frontal appendages. Description ...

''. Like all stem and total group arthropods, ''Titanokorys'' had to shed its outer skin to grow larger. This is evidenced by the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen (ROMIP 65415) which probably represents a collection of molted remains.'''' Sometimes, fossils of these

exuvia In biology, exuviae are the remains of an exoskeleton and related structures that are left after ecdysozoans (including insects, crustaceans and arachnids) have molted. The exuviae of an animal can be important to biologists as they can often b ...

are found alongside numerous specimens of the agnostid arthropod genus ''

Peronopsis ''Peronopsis'' (meaning "broach-like" or possibly "boot-like") is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America. Etymology The subgenus ''Svenax'' is a contrac ...

'' in the immediate vicinity or directly on the exuvia. Why the arthropods were on the exuvia is unclear, but they could have been eating from the molting residues or grazed on a possible

biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...

that was growing on it.

References