''Balhuticaris'' 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 ...

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

bivalved (referring to the carapace) hymenocarine

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 ...

that lived in the

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 ...

aged

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 what is now

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 ...

around 506 million years ago. This extremely multisegmented (with over 100 segments) arthropod is the largest member of the group, and it was even one of the largest animals of the Cambrian, with individuals reaching lengths of 245 mm (9 in). Fossils of this animal suggests that gigantism occurred in more groups of

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 ...

a than had been previously thought. It also presents the possibility that bivalved arthropods were very diverse, and filled in a lot of

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. The hymenocarines were an order of primitive mandibulates, the arthropod group that includes

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

myriapods Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversifi ...

and their relatives, that lived throughout the Cambrian period. This group was extremely diverse and attained a wide variety of ecological niches and body plans. Several dozen species are known from deposits of Cambrian, and ranged in size from smaller species like ''

Fibulacaris nereidis ''Fibulacaris'' is a monotypic genus of fossil arthropod known only by one species, ''Fibulacaris nereidis'', discovered from the Cambrian Burgess Shale of Canada. It was characterized by a bivalved carapace with an inverted rostrum, sandwiching ...

'' reaching a length of long, to larger ones like ''B. voltae''.

Discovery and Etymology

This arthropod was described in 2022 based on 11 specimens found in the Burgess Shale between 2014 and 2018, more specifically in the

Marble canyon Marble Canyon is the section of the Colorado River canyon in northern Arizona from Lee's Ferry to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. Lee's Ferry is a common launching point for riv ...

locality. By 2020, scientists realized that these fossils represented a new species. Because of how they were preserved the fossils were found two dimensional in several

carbonaceous Carbonaceous refers to something relating to, containing, or composed of carbon. It is a descriptor used for the attribute of any substance rich in carbon. Particularly, ''carbonaceous hydrocarbons'' are very unsaturated, high- molecular-weight h ...

films. 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 and several others are nearly or fully complete with possible

neural In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes t ...

and other

soft tissue Soft tissue connective tissue, connects and surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, Adipose tissue, fat, fibrous tissue, Lymphatic vessel, lymph and blood vessels, fasciae, and synovial membranes.� ...

s having been preserved. ''Balhuticaris'' is named after Balhūt, a giant

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

from

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

cosmography The term cosmography has two distinct meanings: traditionally it has been the protoscience of mapping the general features of the cosmos, heaven and Earth; more recently, it has been used to describe the ongoing effort to determine the large-sca ...

, as well as the Latin ''caris'' ("crab"). The specific epithet ''voltae'' is derived from the Catalan ''volta'', meaning vault, referring to the shape of the

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

when seen from the front.

Description

''Balhuticaris'' was the largest bivalved arthropod in the

fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, beating the previous holders of this title ''

Nereocaris ''Nereocaris'' is an extinct genus of bivalved hymenocarine arthropod that lived in the Cambrian aged Burgess Shale in what is now British Columbia around 506 million years ago. Two species are known. History and nomenclature The holotype an ...

exilis'' and ''

Tuzoia ''Tuzoia'' (from Mount Tuzo, a mountain in the Canadian Rockies) is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments from what is now North America, Australia, China, Europe and Siberia. The lar ...

.'' This animal's body was very long, and had extreme segmentation compared to other Cambrian arthropods, with over 100 distinct segments. In total this creature had about 110 pairs of

biramous 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, ...

limbs, the most of any Cambrian-aged arthropod. Covering the head of this creature was a large

that resembles an

arch An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but stru ...

or other curved structure. This structure only covers the frontmost part of this arthropod but it does extend ventrally beyond its appendages.

Classification

In several studies performed, ''Balhuticaris'' was found to be a member of the Hymenocarina. More specifically it was found to be most closely related to the genus ''

Odaraia ''Odaraia'' is an extinct genus of bivalved Hymenocarina, hymenocarine arthropod with a single known species ''Odaraia alata'', found in the Middle Cambrian Burgess Shale in British Columbia, Canada. History of research and taxonomy The genus a ...

'' and its relatives. Although they are normally regarded as

pancrustacea Pancrustacea is the clade that comprises all crustaceans and all hexapods (insects and relatives). This grouping is contrary to the Atelocerata hypothesis, in which Hexapoda and Myriapoda are sister taxa, and Crustacea are only more distantl ...

ns, this study found the Hymenocarina to occupy a more basal branch of the mandibulates. This cladogram shows the position of ''B. voltae'' in relation to other arthropods by López ''et al.'',

2022 The year began with another wave in the COVID-19 pandemic, with SARS-CoV-2 Omicron variant, Omicron spreading rapidly and becoming the dominant variant of the SARS-CoV-2 virus worldwide. Tracking a decrease in cases and deaths, 2022 saw ...

. Cladogram of

Hymenocarina Hymenocarina is an Order (biology), order of extinct marine arthropods known from the Cambrian. They possess bivalved carapaces, typically with exposed posteriors. Members of the group are morphologically diverse and had a variety of ecologies, i ...

, following Izquierdo-López and Caron, (2024), which recovered ''Balhuticaris'' within Odaraiidae:

Lifestyle

This hymenocarine most likely engaged in a fast-paced

nekton Nekton or necton (from the ) is any aquatic organism that can actively and persistently propel itself through a water column (i.e. swimming) without touching the bottom. Nektons generally have powerful tails and appendages (e.g. fins, pleopods, ...

ic (free swimming) lifestyle. Its large size means that it was safe from most of the other predatory

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 ...

of its environment. Many features of the fossils evidence a free swimming,

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

lifestyle. Examples being the presence of a tripartite

caudal ramus The caudal ramus (plural: ''caudal rami'') is a characteristic feature of primitive crustaceans. Located on the anal somite (telson segment), the caudal ramus is a pair of appendage An appendage (or outgrowth) is an external body part or nat ...

, a feature only found in hymenocarines, and that the carapace goes ventrally beyond the legs, which would have heavily impaired this arthropods ability to crawl on the

ocean 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 ...

. Its eyes also have a similar shape seen in modern pelagic crustaceans. What this arthropod ate has been a difficult question to answer due to the lack of

cephalic A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...

appendages in the fossils. Modern day arthropods of a similar size like

lobster Lobsters are Malacostraca, malacostracans Decapoda, decapod crustaceans of the family (biology), family Nephropidae or its Synonym (taxonomy), synonym Homaridae. They have long bodies with muscular tails and live in crevices or burrows on th ...

stomatopod Mantis shrimp are carnivorous marine crustaceans of the order Stomatopoda (). Stomatopods branched off from other members of the class Malacostraca around 400 million years ago, with more than 520 extant species of mantis shrimp known. All li ...

s, and

giant isopod A giant isopod is any of the almost 20 species of large isopods in the genus ''Bathynomus''. They are abundant in the cold, deep waters of the Atlantic, Pacific, and Indian Oceans.Lowry, J. K. and Dempsey, K. (2006). ''The giant deep-sea scaveng ...

s are mainly

scavenger Scavengers are animals that consume Corpse decomposition, dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a he ...

s or predators. ''B. voltae'' however does not possess features that would suggest this, like chelate limbs and gnathobases.

Suspension Suspension or suspended may refer to: Science and engineering * Car suspension * Cell suspension or suspension culture, in biology * Guarded suspension, a software design pattern in concurrent programming suspending a method call and the calling ...

and deposit feeding can also be readily ruled out due to lack of features needed for these lifestyles in ''B. voltae''. Currently it is thought to have suctioned in prey in water currents through a ventral groove. The animal probably swam while it fed, similar to

leptostraca Leptostraca (from the Greek words for ''thin'' and ''shell'') is an order of small, marine crustaceans. Its members, including the well-studied '' Nebalia'', occur throughout the world's oceans and are usually considered to be filter-feeders. It ...

n and

anostraca Anostraca is one of the four orders of crustaceans in the class Branchiopoda; its members are referred to as fairy shrimp. They live in vernal pools and hypersaline lakes across the world, and they have even been found in deserts, ice-covered m ...

n crustaceans. It is possible that this animal swam in an upside down, or in an inverted position. This is not unheard of, as many other free-swimming arthropods like anostracans, pelagic

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

s like the Telephinids,

xiphosura Xiphosura (; , in reference to its sword-like telson) is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Horseshoe crab, Limulidae). They fir ...

ns, and other odaraiid hymenocarines, like ''Odaraia'' and '' Fibulacaris'' swam in inverted positions.

Paleoecology

The Burgess Shale is a middle Cambrian aged

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 ...

that lies in

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

. This site was the first of its kind to have been discovered and provided great insights into the soft bodied

of 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 ...

. Dozens of creatures have been preserved at this site including

lobopodia Lobopodians are members of the informal group Lobopodia (), or the formally erected phylum Lobopoda Cavalier-Smith (1998). They are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as ...

ns,

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

and total-group Arthropoda,

worms The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

, 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 ...

echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...

sponges Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and ar ...

, as well as other animal groups. This animal was one of the largest of its time, with only the giant

radiodonts 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 ...

like ''

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 ...

'' surpassing it in size. More specifically, this animal was found in

Marble Canyon Marble Canyon is the section of the Colorado River canyon in northern Arizona from Lee's Ferry to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. Lee's Ferry is a common launching point for riv ...

. This Lagerstätte produced new taxa including other hymenocarines like ''

Tokummia ''Tokummia'' is a genus of fossil hymenocarine arthropod, known only by one species, ''Tokummia'' ''katalepsis'', from the middle Cambrian (508 million years old) Burgess Shale as found in a quarry in Marble Canyon in Canada. Etymology The ge ...

'', '' Fibulacaris'' and '' Pakucaris'', large

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 ...

radiodonts like ''

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 ...

'' and ''

Titanokorys ''Titanokorys'' is a genus of extinct hurdiid (peytoiid) radiodont (a grouping of primitive stem arthropods which lived during the early Paleozoic) that lived during the Miaolingian epoch of the middle Cambrian. It is the largest member of its ...

'', as well as other arthropods like the megacheiran genus ''

Yawunik ''Yawunik'' is an extinct genus of Cambrian megacheiran ("Great appendage" arthropod) known from the Burgess Shale in Canada ( Marble Canyon locality). The type species has been named ''Yawunik kootenayi'' after the Kootenay, both a geographic ...

'', the isoxyid genus ''

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 ...

'', and the basal

chelicerate The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks ...

'' Mollisonia plenovenatrix''. Worms have also been found at this site, like the annelid ''

Kootenayscolex ''Kootenayscolex'' is the extinct genus of annelid resembling a bristle worm, found in Burgess Shale, British Columbia. It appears to have been an aquatic worm with about 56 chaetae (bristles) on each of up to 25 segments, serving to propel it th ...

''. Well-preserved specimens of primitive chordate ''

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 ...

'' are also known from there.

References