''Dendrerpeton'' (from , 'tree' and , 'creeping thing') 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 an

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 ...

group of

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order (biology), order of small to giant tetrapods—often considered Labyrinth ...

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

s. Its

fossil 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 preserve ...

s have been found primarily in the Joggins Formation of Eastern

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 ...

and in

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

. It lived during the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

and is said to be around 309–316 million years of age, corresponding to more specifically the

Westphalian (stage) The Westphalian is a regional stage or age in the regional stratigraphy of northwest Europe, with an age between roughly 315 and 307 Ma (million years ago). It is a subdivision of the Carboniferous System or Period and the regional Silesian Ser ...

age. Of terrestrial temnospondyl amphibians

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

, it represents the first stage. Although multiple

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

have been proposed, the species unanimously recognized is ''D. acadianum''. This species name comes from “Acadia” which is a historical name for the

Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

region as a French colony. It refers to the location of the coal field at which the fossil was found.

History and discovery

The majority of ''Dendrerpeton'' fossils that had been discovered were disarticulated due to the way in which they had formed. They are often associated with

lycopsid Lycopodiopsida is a class of vascular plants also known as lycopsids, lycopods, or lycophytes. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching stems bearing simple leaves ...

, ''

Sigillaria ''Sigillaria'' is a genus of extinct, spore-bearing, Lepidodendrales, arborescent lycophyte, known from the Carboniferous and Permian periods. It is related to the more famous ''Lepidodendron'', and more distantly to modern Isoetes, quillworts. ...

'', and ''

Calamites ''Calamites'' is a genus of Extinction, extinct arborescent (tree-like) horsetails to which the modern horsetails (genus ''Equisetum'') are closely related. Unlike their Herbaceous plant, herbaceous modern cousins, these plants were medium-size ...

'' tree stumps which decayed inside and became hollow, and are found in Parrsboro formation and the Joggins formation in

. There is also evidence for articulated specimens in

at the Jarrow Colliery. However, they were found to be enveloped by substance that had a very low pH. Although not all specimens were equally affected and some were well preserved, many were not because of this pH. In general, many of the fossils are found in the trunks of these trees or coal swamps. In 1861 one of the first skeleton of ''Dendrerpeton'' ''acadianum'' almost in its entirety was discovered by J.W. Dawson at the South of Joggins, Nova Scotia. It was part of the trunk of a tree, and likely this trunk in which the animal had been was about four feet deep. The skeleton however remained because the bark was preserved due to coal that was

bituminous Bitumen ( , ) is an immensely viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the m ...

. In 1998 came the first skeleton of ''Dendrerpeton'' ''acadianum'' that was nearly completely articulated, again from the Joggins of Nova Scotia. It was essentially undisturbed, and in this case was not associated with a tree but instead with a

boulder In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In ...

found at a beach. This specimen provided the opportunity for a deeper understanding of the skeleton of this taxon because of its three-dimensionality and the detail preserved.

Paleoenvironment and geology

Generally, the distribution of ''Dendrerpeton'' is rather concentrated in the region of

Nova Scotia, Canada Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

, more specifically many specimens were found in the Joggins formation. However, there are also fossils indicating the animals presence in Ireland. In Ireland the environment consisted heavily of coal swamps

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 ...

s which are found in the

. These coal swamps were also found in Nova Scotia, as well as cliffs along the coast. There often are erosions happening in this region with the many cliffs. Also present are

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

that drip downwards of the rocks which have been investigated, and the general climate is predicted to lean more humid, but there are times of shift to drier conditions. It has been predicted that the environment at the time could have undergone fires, which was discovered through the examination of fossil charcoal. This leads to one explanation for the abundance of fossils found within the tree stumps, speaking particularly here about ''Dendrerpeton.'' The occurrence of a fire may have caused them to seek shelter and protection by hiding away into the decayed hollow cores of the trees, as explained by Andrew Scott. However, it is also explained that rather than escaping to the trees by choice, they get trapped. This works particularly for terrestrial animals such as ''Dendrerpeton,'' however other taxa are also found and there is evidence of their survival within these stumps for some period of time, proven by the presence of coprolitic material preserved in the fossils.

Temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished wo ...

are said to be found from the

to the middle-Cretaceous, and ''Dendrerpeton'' considered to be of the earliest or base of the temnospondyls indicating its existence primarily during the

Description

The length of ''Dendrerpeton'' is approximately 35 cm in length according to the measurements done on the nearly fully articulated skeleton, keeping in mind that there was a short portion of the tail posteriorly missing. Additionally, had stated that the maximum length could be up to a

meter The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of ...

Skull and Skeleton

The length of the skull can range from 84 mm to 104 mm for midline length. to Through the analysis of the middle

ear In vertebrates, an ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear co ...

region of ''Dendrerpeton acadianum'', it could be determined that this

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

has a tympanic ear that is not there as a means of support for the palatoquadrate, but rather the positioning of the

stapes The ''stapes'' or stirrup is a bone in the middle ear of humans and other tetrapods which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the f ...

indicates that it is used for the movement of sound. This

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

demonstrates ''Dendrerpeton'' having a hearing system that mimics that of

anurans A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough skin texture due to ...

. This was contrary to what was previously thought, which was that it had a "squamosal embayment" rather than an

otic notch Otic notches are invaginations in the posterior margin of the skull roof, one behind each orbit. Otic notches are one of the features lost in the evolution of amniotes from their tetrapod ancestors. The notches have been interpreted as part of an ...

. However, an otic notch can now be considered a feature of this taxa. Also present are interpterygoid , and a pair of palatal tusks within the

vomer The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms ...

which lay medially to the internal naris. Palatal tusk pairs can also be found the ectopterygoid and the palatine. As for the lower jaw, if the animal catches prey it is able to get it to the denticulate

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

because compression of the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

s is not

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

along their length. The dentary of the lower jaw was found to be the biggest of all the mandibular parts. There also looked to be approximately 40–50 teeth found on each jaw side (in the upper jaw including both the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

and

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

), the marginal teeth. With these teeth ''Dendrerpeton'' can catch larger

prey 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 ki ...

, and was also found to feed on insects which was determined through examination of fossils and presence of insects in the

coal forest Coal forests were the vast swathes of freshwater swamp and riparian forests that covered much of the lands on Earth's tropical regions during the late Carboniferous ( Pennsylvanian) and Permian periods.Cleal, C. J. & Thomas, B. A. (2005). "Pala ...

s. The elements of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

which are on the surface and exposed have s all over. On the dorsal side of the skull and positioned more

posteriorly Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

there is a

foramen In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...

Post-cranial skeleton

Within the

vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...

it is noted that the intercentrum is smaller than the rhomboidal paired pleurocentra and the posterior centrum having a concave shape that will meet with the next intercentrum. The notochord was encompassed by a thickened wall formed by the intercentra. With examination it was also found that a long tail was not likely present in this animal. In regards to the

ribs The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great vessels ...

, they are generally short and

costal cartilage Costal cartilage, also known as rib cartilage, are bars of hyaline cartilage that serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax. Costal cartilage is only found at the anterior ends of the ribs, pr ...

appears to have once been present because of swelling that is found where the end of the shaft is.

Classification

''Dendrerpeton'' is the

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Dendrerpetondtidae which contains both '' Balanerpeton'' and ''Dendrerpeton''. It is part of the order

Temnospondyli Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished ...

. Although it is most commonly known for the species ''D. acadianum,'' there have also been other species names proposed. However, there seems to be discussion on whether any of them are valid enough to distinguish as a separate species of their own. An example of one of these species is ''Dendrerpeton oweni'', which Robert Carroll claimed had no particular distinguishable feature and looked to be simply ''Dendrerpeton acadianum'' but smaller because it is of younger age.