Eurotamandua

Eurotamandua joresi, fossil in the Senckenberg Research Institute

Germany ( Messel, Geisel )

Eurotamandua is an extinct genus from the order of Pholidota, which also includes the extant pangolins ( Manidae ) belong. The first fossil was found in 1974 in the Messel Pit near Darmstadt and firstdescribed seven years later scientifically. Other finds are known from the Geisel. All discovered remains are assigned to the Middle Eocene and are thus around 47 million years old. After the describer believes that it was a representative of the extinct giant anteaters ( Vermilingua ), which Eurotamandua would be the oldest known fossil of this animal group, which is otherwise only found in South America. Renewed studies on the phylogeny make but a closer relationship with the pangolins likely. Characteristics of Eurotamandua are tubular and toothless snout and the typical construction of the forelimbs with an extended middle finger.

Description

Eurotamandua reached on the basis of a complete skeleton discovery a total length of about 86 cm, about 36 cm which was attributable to the tail. Overall, it was a bulky and powerful animal with numerous adjustments to a specialized lifestyle. The skull was 8.8 cm long and was relatively small in comparison to the body. In the side view he had a smooth forehead line, the skull profile fell slightly only in the area of the rostrum. The rostrum was also extended tubular and thus resembled today's pangolins and anteaters. The elongated nose measured 3.7 cm and thus took about 42 % of the total skull length a. The margins showed a curved design, while the rear end clearly projected into the frontal bone. Below the nasal bone sat directly on the central jaw bone, which was extremely short with 0.8 cm in length. The upper jaw was not part of the orbital rim. Notwithstanding today's pangolins and anteaters of the zygomatic arch was fully formed but poorly developed. The mandible was 6.5 cm long and had the form of a long, narrow clip. The symphysis showed in the side view, a slight broadening and a slight downward curve. Lack of alveoli in the maxilla and mandible indicate that Eurotamandua was completely edentulous.

The postcranial skeleton is well known, the number and the exact appearance of the vertebrae but surely only for the rear body section. So was the spine of well 7 cervical, at least 9 breast, 4 lumbar, 5 sacral, and 24 caudal vertebrae. On the good traditional tail spine had only the front vortex functioning vertebral arches and wide transverse processes, the rear were cylindrical and simple. The length of the vortex took back continuously, from 1.8 cm length in the anterior caudal region to 0.8 cm in length in the back. The front and hind limbs were formed about the same length and strong. The humerus measure be up to 7 cm and had a short, sturdy construction. Radius and ulna were not interconnected. Additionally, possessed the cubit, which reached up to 8.5 cm in length, with a 2.4 cm right extended upper joint ( olecranon ). The femur was up to 8 cm long and was also robust. The third trochanter, typical of pangolins and anteaters, took about 30 % of the lateral bone shaft, but was not particularly prominent. Even the tibia and fibula were free, both distinguished themselves by just running diaphysis. The former bone had a length of 7, the latter of 6.1 cm in length. Front and hind feet showed five rays of the forefoot, however, was significantly greater. Striking appeared while the midstream (III ) of the hand, which was significantly extended, especially at the Endphalange whose length was 2.7 cm. The significantly convex curvature of the distal phalanges indicates that they were originally equipped with powerful claws, their attachment is indicated by a distinct groove on the side of the phalanges.

Fossil finds

The most important fossil of Eurotamandua, a complete, lying on its side skeleton of a nearly full-grown animal, according to statements by Kenneth D. Rose one of the most beautiful and vexing of Messel fossils ( "one of the most beautiful and the most annoying of the Messel fossil " ), was already in 1974 by Gerhard Jores in the northern part of the Messel Pit, the so -called Long slope in the grid squares F 6/7, have been found. It is extraordinarily well preserved, but individual Disartikulationen found in the front body portion of the spine and the upper portion of the front limbs. The preparation was carried out in the following part, by the discoverer himself more finds come from the lower coal of the Geisel valley near Halle in Saxony- Anhalt. These include isolated remnants of the right forelimb with the humerus and the ulna. Both sites belong to the Middle Eocene ( lokalstratigraphisch in the section lutetium dated) and are about 47 million years old.

Paleobiology

Overall, this is at Eurotamandua a powerful animal. The preservation of the forefoot can present allow any interpretation of the movement, it is both a plantigrade gait possible as well as a folding of the claws on the palm, as it is known in the pangolins and anteaters. The strong reduction of the outermost finger beam ( V ), the latter makes quite probable. The hind feet, however, were focused on a sole transition. The long, slim tail with a short front section consisting of more differentiated vertebrae was most likely not as supporting or grasping organ. The structure of the skull with the tubular snout and toothless bite, but also the extended claw of the middle finger can be a strong specialization in social insects such as ants and termites close ( Myrmecophagie ), similar to the in today's pangolins and similarly for the anteaters of case. The sharp claws of the forefoot, especially of the middle toe served to break up the Insektenbaue. The Messel Fossil leaves due to its good quality in addition to the very detailed study of skeletal elements, including measurements of stomach contents to. In the stomach data could be found by Chitinhäuten, but lacking typical head capsules or teeth structures. This outweighed quergeschuppte Cuticulen, some of which are highly folded and resemble the abdomens of today's termites, however, is not possible an unambiguous assignment as termites or ants residues. In addition, a greater proportion of wood structures found in an unspecified to be determined, cemented matrix, which are comparable with the nesting materials today termites tree with pieces of wood in the hardened saliva. These plant remains are known as " by-catch " of the food intake of Eurotamandua conceive that occurred well as in modern pangolins and anteaters with a long, sticky tongue. In addition are from the stomach contents from numerous grains of sand. Today's pangolins and anteaters often swallow sand to crush the swallowed chewed because of the edentulous jaw food in the stomach.

Systematics and history of research

Eurotamandua an anteater?

Eurotamandua was first described scientifically in 1981 by Gerhard Storch using the full skeleton from Messel ( copy number SMF Me 80/24 ). In his first description Stork Eurotamandua referred to as a generic anteater ( Vermilingua ) and in a more precise relationship with the Great Anteater ( Myrmecophaga ) and the Tamanduas ( Aardvark ), which represent the family of Myrmecophagidae. Here, the scientific genus name Eurotamandua takes into account both the assumed close relationship to the Tamanduas as well as the location of the fossil finds in Europe. As reasons for the close relationship with the anteaters included the then recognized training xenarthrischer joints ( secondary joints or Xenarthrale ) to the articular processes ( zygapophyses ) the posterior thoracic and anterior lumbar vertebrae, one of the central features of the Xenarthra and thus the anteaters, but also pulled down symphysis of the mandible and the expression of the front limbs, additionally indicated the typical training of hearing as well as the special, greatly prolonged backward construction of the palate. General was the body similar to that of native to South America Tamanduas that specialize as less as compared to the other anteaters known and both on the ground and in trees live. Other similarities were also noted to the pangolins, which largely were just as primitive features.

According to his first description Eurotamandua the oldest known ant-eater would have been at all and the only one who had ever been discovered outside of America with an age of 47 million years ago at the time. The anteaters include a highly specialized group within the Xenarthra ( Xenarthra ). The phylogenetic relationship of the Xenarthra has not always been clarified in the past. Originally, this together with the aardvarks ( Orycteropodidae ) and pangolins ( Manidae ) in 1798 were directed by Georges Cuvier in the order of Toothless ( Edentata ). Although the concept of Edentata was doubted in the second half of the 19th century and removed much of the early 20th century, but led some researchers until well into the 1990s both the pangolins (within the Pholidota as parent group ) and the Xenarthra as the core components of the Edentata, so among other things, in the first description of Eurotamandua.

Biogeographic controversy

The Xenarthra are now spread to the Americas. Its origin lies in the Paleocene of South America, but maybe he goes back to the Late Cretaceous. Only from the middle Pliocene with the emergence of a land bridge at the Isthmus of Panama reached some representatives also Central and North America. Originally from Europe, Asia and Africa described fossil taxa of the Xenarthra proved in retrospect to other groups belonging, about to shed lizards or pangolins and their relatives. To justify the presence Eurotamanduas in Europe and its relationship to the anteaters, different paleogeographic observations were used. As an alternative, was the immigration across North America, but a more favored place with the over Africa, which had separated out in the Upper Cretaceous million years ago, around 80 to 100 of South America. In the same time, the emergence of the early mammalian groups including the Xenarthra dated, which Eurotamandua could have stemmed from a very early line of anteaters. This should then have inhabited parts of the African continent later, after which the ancestors of Eurotamandua have achieved in the late Cretaceous or early Tertiary of the Tethys Europe. Further phylogenetic studies based on morphological characters of extant and fossil taxa from 1998 supported this thesis partially and placed Eurotamandua to the base of the anteaters or alternatively involving the Pholidota on the basis of all edentates ( Pilosa ), the combined group of anteaters and sloths ( Folivora ). Analyzes of the same year, however, meant that although Eurotamandua excluded from the direct relationship of the Xenarthra, but was relegated to the newly created specially order Afredentata as its only member. In this case, an origin was considered by the Xenarthra animals than likely was just like a closer kinship assumed to Palaeanodonta. This extinct, once ground-dwelling animals are but in today's opinion the pangolins close.

Today's position

Euromanis

Eurotamandua

Eomanis

Necromanis

Patriomanidae

Manidae

Palaeanodonta

The view above the close relationship Eurotamanduas with the anteaters was viewed with skepticism in the 1990s. Some phylogenetic analyzes placed instead close a relationship with the Palaeanodonta. Molecular genetic analyzes during this time was also recognized that the shed and the animals are not further Xenarthra related. Thus, the Xenarthra form are as sister group against one of the four major main lines of higher mammals, the other three (collectively Epitheria ). Together with the predators ( Carnivora ) The pangolins ( order Pholidota ) form the parent taxon ferae, which constitutes a part of the main line of Laurasiatheria. The superficial similarities of pangolins and Xenarthra, but especially the anteaters - such as the tubular snout, toothless jaws, long, sticky tongue and the design of the front legs - go back on convergent developments that arose due to the similar lifestyles of the two groups of animals.

Re- anatomical studies of extant pangolins and their fossil relatives in 2009 have now shown that Eurotamandua is to provide in the order of Pholidota, however, was not an accurate family assignment. Reasons for the reassignment be with the misinterpretation of xenarthrischen joints - these were later found as a result of the restoration work - given the special structure of the front legs and the front legs and especially the different arrangement of the articular surfaces of the metacarpal and finger bones differ significantly in spite of the general similarities of the anteaters. The Pholidota together with the extinct Palaeanodonta which are known from the Paleogene of North America and Europe, the parent group of Pholidotamorpha. Within the Pholidota provide Eomanis and Euromanis the closest relatives of Eurotamandua represents; these two genera were found in the Messel pit, and stand together on the basis of the development of the pangolin relatives. You still have lots of original features which they have in common with the Palaeanodonta areas, including through a C-shaped designed means jaw bone, a small bone rib at the posterior end of the jaw and some special characteristics of the forelimb such as the extended end links of the front feet are. The appearance of the primitive representatives of Pholidota in Messel leads to the assumption that the entire group may be developed in Europe and later spread only after Asia and Africa. Partial Euromanis was known previously only on the basis of a skull -less skeleton and was originally described as Eomanis krebsi, as a young animal of Eurotamandua and therefore as identical to this one. This was however contradicted and pointed to marked differences especially on the hind legs. Currently, with Eurotamandua joresi only a valid type is known, which was first described by Gerhard Storch after the discoverer of Messel skeleton, Gerhard Jores, named in 1981.

Swell

• Norbert Micklich: The collection Behnke and the anteater " Eurotamandua joresi " - Outstanding fossil finds from the Messel Pit. Cultural Foundation of the Countries, Berlin 2001 ( Patrimonia 211, ISSN 0941-7036 ).