''Daidal'' (named after a spirit in

Takelma The Takelma (also Dagelma) are a Native American people who originally lived in the Rogue Valley of interior southwestern Oregon. Most of their villages were sited along the Rogue River. The name ''Takelma'' means "(Those) Along the River". Hi ...

mythology) is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

mantis shrimp Mantis shrimp, or stomatopods, are carnivorous marine crustaceans of the order Stomatopoda (). Stomatopods branched off from other members of the class Malacostraca around 340 million years ago. Mantis shrimp typically grow to around in length ...

that lived during the Carboniferous period. It is the only genus in the family Daidalidae. Three species are currently placed within the genus. Fossils of the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

, ''D. acanthocercus'', have been found in the

Bear Gulch Limestone The Bear Gulch Limestone is a limestone-rich geological lens in central Montana, renowned for the quality of its late Mississippian-aged fossils. It is exposed over a number of outcrops northeast of the Big Snowy Mountains, and is often considere ...

Montana Montana () is a U.S. state, state in the Mountain states, Mountain West List of regions of the United States#Census Bureau-designated regions and divisions, division of the Western United States. It is bordered by Idaho to the west, North ...

. A second species, ''D. pattoni'', is known from the

Lower Limestone Formation The Clackmannan Group is the name given to a suite of rocks of late Dinantian and Namurian age laid down during the Carboniferous period in the Midland Valley of Scotland. Description The Group comprises a lower unit of coarse sandstones, ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to th ...

, and the third species, ''D. schoellmanni'', was discovered in

Westphalia Westphalia (; german: Westfalen ; nds, Westfalen ) is a region of northwestern Germany and one of the three historic parts of the state of North Rhine-Westphalia. It has an area of and 7.9 million inhabitants. The territory of the regi ...

, Germany. The genus has been proposed to be

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

, with ''D. pattoni'' possibly being an earlier diverging lineage, though more specimens and research are needed to confirm this.

Taxonomic history

Fossilized remains of ''Daidal'' were first described almost a century before the

was named. In 1908,

Ben Peach Benjamin Neeve Peach (6 September 1842 – 29 January 1926) was a British geologist. Life Peach was born at Gorran Haven in Cornwall on 6 September 1842 to Jemima Mabson and Charles William Peach, an amateur British naturalist and geologi ...

studied several

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

fossils from the Carboniferous deposits in

, and erected the species ''

Perimecturus ''Perimecturus'' is an extinct genus of mantis shrimp that lived during the Early Carboniferous period in what is now Scotland and the United States. The first known specimens were collected near the River Esk, Dumfries and Galloway, River Esk in ...

pattoni'' based on a single specimen (G 1887.25.1059) collected from the Top Hosie Limestone of the

near

East Kilbride East Kilbride (; gd, Cille Bhrìghde an Ear ) is the largest town in South Lanarkshire in Scotland and the country's sixth-largest locality by population. It was also designated Scotland's first new town on 6 May 1947. The area lies on a raise ...

, believing it belonged in the genus ''Perimecturus''. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honors Andrew Patton, manager of the Calderwood Cement Works, who collected this fossil. Clark (1989) would report on additional material of this species and move it into the genus ''

Tyrannophontes ''Tyrannophontes'' is an extinct genus of mantis shrimp that lived during the late Carboniferous period in what is now the Mazon Creek fossil beds of Illinois. It is the only genus in the family Tyrannophontidae. The type species, ''T. theridion' ...

'' as ''Tyrannophontes pattoni'', though Lothar Schöllman placed it back into ''Perimecturus'' in 2004. Jenner ''et al.'' (1998) analysed numerous

stomatopod Mantis shrimp, or stomatopods, are carnivorous marine crustaceans of the order Stomatopoda (). Stomatopods branched off from other members of the class Malacostraca around 340 million years ago. Mantis shrimp typically grow to around in length ...

specimens from the

. They recognized that some of these specimens, formerly thought to represent ''

Bairdops ''Bairdops'' is an extinct genus of mantis shrimp that lived during the Early Carboniferous period in what is now Scotland and the United States. Two named species are currently assigned to it. The type species, ''B. elegans'', has been collected ...

beargulchensis'' or ''

'' ''theridion'', represent a new species which they named ''Tyrannophontes acanthocercus''. The specimen CM 34453 was selected as the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

of this species. The specific name is combined from the Greek ''akanthos'' (meaning "thorn") and ''kerkos'' (meaning "tail"), in reference to the spines on the

telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ...

. Lothar Schöllman studied the remains of another stomatopod species collected from Hagen-Vorhalle,

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

, and in 2004 he concluded they were mostly similar to '' Gorgonophontes'', assigning them to ''Gorgonophontes'' cf. ''fraiponti''. Other authors before him had tentatively assigned the specimens to ''Perimecturus'' or ''Tyrannophontes''. In 2007,

Frederick Schram Frederick Robert Schram (born August 11, 1943, in Chicago, Illinois) is an American palaeontologist and carcinologist. He received his B.S. in biology from Loyola University Chicago in 1965, and a Ph.D. on palaeozoology from the University of Ch ...

conducted a study revising the classification of

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

s. He found that the fossils assigned to ''Tyrannophontes acanthocercus'' differed significantly from the holotype of ''Tyrannophontes'', and that the species should be placed in a separate genus. The genus ''Daidal'' was thus erected, with ''T. acanthocercus'' (now renamed ''Daidal acanthocercus'') as the

. The generic name references a spirit in

mythology of the same name. Schram also found ''Perimecturus pattoni'' to be similar to ''D. acanthocercus'' in features of the

pleon The decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various g ...

and telson, therefore reclassifying it as a second species of ''Daidal'' now named ''Daidal pattoni''. In addition, the German remains assigned to ''Gorgonophontes'' cf. ''fraiponti'' were also discovered by Schram to be similar to specimens of ''Daidal'', so the species ''Daidal schoellmanni'' was erected based on them. The specific name honors Lothar Schöllman for his earlier work on this species.

Description

''Daidal'' is an

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

of moderate size, with the type species ''D. acanthocercus'' reaching a body length of . Each

antennule Antennae ( antenna), sometimes referred to as "feelers", are paired appendages used for sensing in arthropods. Antennae are connected to the first one or two segments of the arthropod head. They vary widely in form but are always made of one o ...

has three

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

e of around equal length. The

mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

are large and heavily

sclerotised Sclerotin is a component of the cuticle of various Arthropoda, most familiarly insects. It is formed by cross-linking members of particular classes of protein molecules, a biochemical process called sclerotization, a form of tanning in which qu ...

, located around three fifths the length 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 und ...

from the posterior edge of the carapace. The carapace is only slightly longer than it is tall, enveloping the front of the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the ...

(apart from its underside), with a subtriangular shape in side view and subrectangular shape in top view. The top of the carapace extends towards the front margin of the fifth thorax segment, while wing-like extensions on its sides extend to the front margins of the sixth thorax segment, and a furrow stretches along the carapace margins. Daidal

The second to fifth thorax segments each possess a pair of

maxilliped An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including ant ...

s (appendages which function as mouthparts), which are similar in shape and size. These are enlarged and served as

raptorial The term ''raptorial'' implies much the same as ''predatory'' but most often refers to modifications of an arthropod's foreleg that make it function for the grasping of prey while it is consumed, where the gripping surfaces are formed from the o ...

appendages for catching prey. The propodi (penultimate segment) of the maxillipeds are large and subrectangular, with two parallel rows of spines: a row of moveable large spines on the outer side and a row of small spines on the inner side. The dactyli (final segment) of the maxillipeds are thin and blade-like, curving towards the body. The

is around a third longer than the

cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''ceph ...

, with each segment being slightly larger than the one in front of it. The segments are non-overlapping and have rounded corners, with furrows and ridges on the margins. The

pleopod The decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various ...

s are heavily sclerotized, with the terminal segment being greatly enlarged. In ''D. acanthocercus'' and ''D. schoellmanni'' the

tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

s are undecorated, whereas those of ''D. pattoni'' have rippled decoration. The segment of the

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

closest to the body has two backwards-pointing spines. Paired

keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in B ...

s are present on the subrectangular and tapering

, as are four movable spines on the margins of its underside.

Classification

The species now assigned to ''Daidal'' have been placed in various other

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...

in the past, and thus have also been positioned in different

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

. ''D. acanthocercus'' was initially described as a species of ''

,'' while ''D. pattoni'' was first named as a species of ''

'', and therefore were assigned to the families Tyrannophontidae and Perimecturidae respectively. The specimens of ''D. schoellmanni'' were at one point associated with the genus '' Gorgonophontes'' and by extension the family Gorgonophontidae.

was the first to recognize these species as members of the genus he named ''Daidal'' in 2007, and erected the family Daidalidae for this genus. The family belongs to the suborder Archaeostomatopodea and is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

, with ''Daidal'' being the type and only genus. Smith ''et al.'' (2023) conducted a

phylogenetic analysis In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that pro ...

to determine the relations between fossil mantis shrimps, which recovered the genus ''Daidal'' to be

. While ''D. acanthocercus'' and ''D. schoellmanni'' were recovered as sister taxa, these two species were also recovered to be more closely related to ''Gorgonophontes'' than to the earlier-diverging ''D. pattoni''. However, it was noted that this result may be due to a lack of data on the

thoracic The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

appendages of ''D. pattoni''. The results of the analysis are displayed in the

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

below:

Palaeobiology

Based on the diet of other

s and the fact that it has enlarged

appendages, ''Daidal'' is believed to have been a

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

. In extant

unipeltata Mantis shrimp, or stomatopods, are carnivorous marine crustaceans of the order Stomatopoda (). Stomatopods branched off from other members of the class Malacostraca around 340 million years ago. Mantis shrimp typically grow to around in length, ...

n mantis shrimps, the raptorial appendages (the second pair of

thoracopod 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, plur ...

s) have a specialized joint associated with a set of muscles to form a click-joint mechanism, allowing the appendages to rapidly extend and capture prey. However, ''Daidal'' probably lacked this mechanism, instead having raptorial appendages that more closely resemble the smaller, third to fifth thoracopods of unipeltatans used to manipulate prey after capture. It has thus been suggested by Jenner ''et al.'' (1998) that basal

s like ''Daidal'' were opportunistic

scavenger Scavengers are animals that consume 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 herbivorous feeding b ...

s which primarily handled dead food. On the other hand, Haug & Haug (2021) theorized that early mantis shrimps were

benthopelagic The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer o ...

predator Predation is a biological interaction where 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 ...

s, swimming above the seabed while they hunted, possibly by grabbing their prey from above. This was supported by the appendage morphology in '' Tyrannosculda'', ''

'' and '' Gorgonophontes'', showing these early forms could not attack prey from the seabed. This method of hunting is also observed in the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. Th ...

e of extant mantis shrimps, and studying them may help increase our understanding of early stomatopod ecology.

References

{{Taxonbar, from=Q123409912 Carboniferous animals of North America Carboniferous arthropods of Europe Stomatopoda Fossil taxa described in 2007 Prehistoric crustacean genera Prehistoric mantis shrimps