Heterohyus

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Heterohyus
Skeleton of heterohyus

Skeleton of heterohyus

Temporal occurrence
Eocene
50.7 to 33.9 million years
Locations
Systematics
Tetrapoda (land vertebrates)
Mammals (mammalia)
Higher mammals (Eutheria)
Apatotheria
Apatemyidae
Heterohyus
Scientific name
Heterohyus
Gervais , 1848

Heterohyus is an extinct genus of insectivore-like mammals that wascommonin present-day Europe from the Lower to the Upper Eocene 51 to 34 million years ago. They are small animals with characteristically enlarged front teeth and two elongated fingers. Due to the combination of features, there are similarities to today's fingertip from Madagascar and the striped pouches from New Guinea . Like these, Heterohyus probablylivedin trees and gnawed bark with its front teeth while its long fingers digged for insects in crevices and cavities. Heterohyus fossilshave been found in the central and western areas of the continent. Usually only parts of the skull and teeth are present, some well-preserved skeletons are documented from the Messel pit . The genus was first described scientifically in the middle of the 19th century, but its exact systematic position remained unclear for a long time. Today it is placed among the Apatotheria , which may be more closely related to the rodents and the Euarchonta . Several species are distinguished within the genus.

description

Heterohyus was a small representative of the mammals. Individual complete skeletons of small members of the genus have a head-trunk length of 11.5 to 13.6 cm and a tail length of 15 to 17.4 cm. In terms of body size, these roughly correspond to today's dormouse . With reference to the available skull material, the largest forms of Heterohyus are likely to have been about five times as large. The skull itself was about 38 mm long in the small Heterohyus species. In comparison with the rather delicate skeleton structure, it was massive. The high and short middle jawbone also made it look rather dull. The anterior border of the orbit was above the first molar , it was open to the rear and therefore had only a weakly developed supraorbital process . The infraorbital foramen was slightly recessed compared to the anterior orbital margin above the first and second molars. The pre-eye pit took a similar position in Apatemys , Carcinella and Sinclairella . Numerous other foramina opened in the snout area, especially in the area around the incisors . The zygomatic arch was massive and strongly curved. There was a small pit below the front arch attachment, which is also found in other apatemyids such as Sinclairella . There were also numerous foramina in the back of the skull. Similar formations have been reported by Apatemys and Sinclairella . On the parietal bone rose a strong crest , as it is also documented by Carcinella . In Sinclairella, on the other hand, there were two parasagittal ridges, while in Stehlinella neither of the two features occurred.

The lower jaw was about 22 mm long and the crown process 12.5 mm high. The symphysis in the front area was not fused. The two halves of the lower jaw opened forward in the alveoli of the massive lower incisor, the root of which reached to the last molar. In contrast to today's rodents, which also have powerful incisors, this did not determine the contour of the lower jaw. The mental foramen had its opening below the second molar. The ascending branch started at an angle of 130 to 140 ° to the occlusal plane and was thus flatter than in Sinclairella's . The anterior margin of the masseteric fossa emerged as sharply delineated. There was a distinct angular process at the posterior end of the lower jaw.

The bit of Heteryus was reduced in number of teeth and dental formula was: . Compared to the older Apatemyids, the number of premolars had decreased; the first and third premolar teeth were missing. The latter still occurred with more primitive representatives like Labidolemur . A canine tooth was generally not developed in the Apatemyids. The most noticeable peculiarity in the dentition of Heterohyus and other Apatemyids can be found in the massive and large incisors. The upper two pairs of teeth therefore also gave rise to the high design of the middle jaw bone, which supported it completely. The inner upper had a semicircular curvature, it tapered to a point and had a small additional cusp on the back of the tooth. The outer incisor was less curved. In the lower jaw, the single incisor stood obliquely forward ( procumbent ) and curved regularly over its entire length. The upper incisors were completely covered with tooth enamel , which was clearly thinned on the back, while the lower incisors only had enamel on the front. In the upper dentition a short diastema separated the anterior from the posterior dentition. Additional gaps between the premolar teeth, as can still be observed in Labidolemur or Apatemys , were missing in Heterohyus , so that the rear row of teeth was closed. The anterior lower premolar, which was greatly enlarged and had an elongated and laterally narrowed tooth crown, which created a long cutting edge, is striking. Despite its size, it only had one root. The posterior lower premolar, on the other hand, was small and pin-like; it did not reach the level of the occlusal plane. In principle, its crown did not protrude above that of the anterior premolar, as has also been documented for Apatemys and Carcinella . The upper molars were characterized by four main cusps (para- and metaconus on the cheek, proto- and hypoconus on the tongue side). The paraconus towered over the metaconus in height, next to these two main cusps on the cheek side a smaller side cusp rose with the parastyle. With regard to the hypoconus on the tongue side, there were variations within the genus Heterohyus , as some species were more pronounced and others less pronounced. Hypoconus was also present in Apatemys , Labidolemur, and Sinclairella , but was absent in Carcinella . As a result, the four-humped occlusal surface pattern of the upper molars can be evaluated as a sign of phylogenetically younger forms. The lower molars also had four main cusps (protoconid, metaconid, paraconid and hypoconid). Here the individual representatives showed greater variations with regard to the paraconide.

The first two cervical vertebrae, 13 thoracic, 6 lumbar, 2 sacrum and 34 to 35 caudal vertebrae have been handed down from the spine. The tail was very long and exceeded the rest of the body in its extension. The size of the caudal vertebrae decreased continuously towards the rear, so that the tail became more and more slender. There were clear transverse processes on the foremost about a dozen. The remaining caudal vertebrae were cylindrical in shape. The rib cage consisted of twelve or thirteen pairs of ribs. The front limb bones were relatively slender and long. The shoulder blade and sternum were connected by a relatively robust collarbone . The humerus was about 18 to 21 mm long and had no noticeable muscle marks, but a strong roughening stretched over about a third of the bone shaft. The ulna and spoke were not fused together. The radius was only slightly longer than the humerus at 21 mm, the ulna was significantly more extensive at 26 mm. The latter bone had a massive upper articular process ( olecranon ). The hind leg was longer and stronger than the front leg. At the pool is a long recorded ilium from. The femur was about 27 mm in length and was straight and elongated in shape. The shin became similarly long. It may have fused to the fibula at the base . The shafts of the two bones were completely free from each other.

The hands and feet were each constructed with five beams. The hand which, in addition to the enlarged incisors, provides the most striking peculiarities of the apatemyids is remarkable. Here the metacarpal bones and phalanges showed marked extensions on the second and third rays. The second and third metacarpus reached a length of 9.5 and 9.2 mm, respectively, while the one on the inner ray was only 5.8 mm long, the one on the outer one was only 4.5 mm long. The effect of the elongated middle fingers was increased by the stretching of the individual phalanges. The first phalanx in each case had a length of 8.5 mm on the second and third finger and was therefore almost as long as the corresponding metacarpal bone. The second phalanges measured 5.5 to 6.5 mm. They thus exceeded the respective phalanges of the other rays by around twice as long. The terminal phalanges on all five fingers, on the other hand, were comparatively short at 1.5 to 2 mm. They tapered towards the front and showed narrowing at the sides. In addition, each of them had a strong tendon hump at the base. As a further special feature of the second and third finger rays, it can be emphasized that the individual bone elements corresponding to one another had slightly different sizes from one another, but both rays had the same length overall. Compared to the highly specialized hand, the foot was built relatively originally and showed no stretching. The individual bones had a stronger structure than their counterparts on the hand. Rays II to IV were almost the same length, the length of the metatarsal bones varied between 10.3 and 11 mm, the first two phalanges were 5.5 and 3.7 mm long. The outer beam did not quite reach the dimensions of the three central beams, the inner beam was significantly shorter. The terminal phalanges of the toes resembled those of the hand.

Fossil finds

Remains of Heterohyus are spread across large areas of Europe . In general, however, they are rather rare and are mostly limited to individual teeth or dentures, so that the animals can be seen as a rare element of fauna. The earliest occurrence is marked by some molars from Cuis and Grauves in France, which date to the Lower Eocene . The most recent records of Heterohyus , however, include those from the transition from the Middle to the Upper Eocene, for example the finds from the Creechbarrow limestone formation in the Hampshire Basin in England or from the phosphorite deposits near Quercy in southern France. The first site includes more than a dozen teeth plus a lower jaw fragment, the latter is also made up of tooth material from a wide variety of sites, the oldest of which was presented at the end of the 19th century. The ten tooth remains from Sossís in northeastern Spain should come from roughly the same time horizon. With a position in the Upper Eocene somewhat younger, individual tooth finds from the Headon Hill Formation are also located in the Hampshire Basin.

An important complex of finds is from Egerkingen in Switzerland, which contains a wide variety of lower and upper jaw fragments as well as individual teeth and belongs to the Middle Eocene. The remains have been noticed since the second half of the 19th century. Something similar can be said of Bouxwiller in the north-eastern French department of Bas-Rhin , which contained the type material of the genus. A few specimens, including a left lower jaw fragment with a preserved incisor and the row of rear teeth from the third premolar to the last molar , which are a good 15 mm long, came to light from the middle to upper coal of the Geiseltal in Saxony-Anhalt. The earliest find was discovered here during research excavations in the 1920s. The most important finds so far have been found in the Messel Pit in Hesse. At least four largely complete skeletons come from here, all of which have been preserved in the lateral position and in some cases still show the contours of the former soft tissue cover. The first find was made by a private collector in 1973, but it was only later recognized as belonging to Heterohyus . The other three skeletons came to light during regular excavations in the 1980s and 1990s. All skeletons represent young animals due to the bone sutures that have not grown together . The good preservation of the Messel skeletons with hardly any disarticulation is possibly due to fat-hardening processes during the carcass embedding in a moist environment.

Paleobiology

Biological functions

Comparison of the finger bones of some apatemyids with those of some recent mammals

The well-preserved skeletons from the Messel mine allow, at least for the smaller representatives of the genus Heterohyus, an insight into the way of life. In connection with other excellently preserved remains of related forms, for example from Apatemys from the Fossil Butte Member of the Green River Formation or from Labidolemur from the Willwood Formation , both located in the US state of Wyoming , this gives a very detailed look at the Biology of the Apatemyidae. All in all, Heterohyus is a relatively gracefully built animal, whose smaller members reached the size of today's dormouse . For the genus, as for other members of the family, the combination of the enlarged and protruding incisors and the elongated phalanx is striking. A comparable combination of characteristics is now found in the finger animal ( Daubentonia ), a primate species in Madagascar , and in the striped buccaneers ( Dactylopsila ) from New Guinea , which results in a clear convergent development. In both genera, the animals use their long fingers to dig insects and their larvae out of crevices and cracks in the tree bark, while the animals gnaw to expand the cavities with the large incisors. A comparable way of life can be assumed for heterohyus . The gnawing use of the incisors is supported in the principally high skull and the projecting zygomatic arches, which means that there are sufficiently large attachment points for the masticatory muscles. The enamel covering only individual areas of the incisors had the effect that the tips of the teeth were repeatedly sharpened during use. However, there are deviations from the finger animal and the striped pouches in the further appearance of the teeth. In the case of the finger animals, there is a larger tooth gap on the lower incisor (as well as on the upper one), whereas in the striped pouches there are several very small pre-grinding teeth. In contrast, in the case of heterohyus, the large anterior premolar with the long cutting edge connects directly to the incisor in the lower dentition. Furthermore, the upper front dentition in the striped pouches consists of three incisors, of which only the first is greatly enlarged, the others are flat and low. When the bite is closed, these two lie on the lower large incisor and are ground flat by this. The teeth behind it in the striped pouches, a canine and several premolars, are not in contact with the lower incisor. This different set of teeth may have resulted in differences in the details of the diet. The numerous foramina in the snout area, which indicate the presence of vibrissae, can also be interpreted in connection with the intake or procurement of food or as an indication of movable lips . The greatly shortened terminal phalanges of the fingers of Heterohyus can be used well as barbs when poking in tree holes or for fishing out insects. The robust tendon hump at the base of the phalanx can serve as an indication of this. Striking differences, however, result from the position of the extended fingers. While the third and fourth rays are elongated in the case of the auger and the striped pouches, the second and third rays of the Heterohyus show these characteristics. The slightly modified anatomy of the two elongated fingers in Heterohyus can be interpreted to mean that they were not used at the same time or that they had a slightly modified function or possibly acted against each other. It remains unclear whether the very great representatives of Heterohyus followed a comparable way of life. Too little fossil material has survived here. A similar problem arises with the extinct relative of the finger animal, the comparatively extremely large Daubentonia robusta . Today's finger animals are also significantly larger than the smaller members of Heterohyus and feed on seeds and fruits in addition to wood-boring insects. The large heterohyus forms may have opened up additional other food sources.

Heterohyus skeleton from the Messel Pit with preserved soft tissue outline

Some skeletons from Messel show the former outline of the body and the fur covered by bacterial traces ( bacteriography ). The traces are close to the skeleton. The entire torso was probably covered with longer hair. Thicker, possibly bristle-like hairs appeared only on the neck. The tail is noticeable, the tip of which has a thick tuft of hair in one specimen, which attaches between the 27th (ventral side) and 32nd (back side) caudal vertebra and takes up around 15% of the tail length. Individual hairs are around 15 mm long. The rest of the tail was probably only sparsely covered with fur, as some individual hairprints show. Striking tail tufts are occupied by numerous tree-living or jumping mammals and often serve as a control organ in locomotion. These include primates such as the tarsius or Senegal Bushbaby or under the tree shrews , the spring-tailed tree shrews , all nimble tree Springer and -kletterer. In addition, individual rodents such as the South African jumping hare or the horse jumpers as ground-dwelling jumpers or the dormouse tails or brush prickles as tree climbers also show a comparable tail end. In contrast to many of the recent jumping mammals, however , Heterohyus does not have any adaptations to such a way of life, since the hind limbs are only moderately elongated. However, the presumed diet implies a tree-climbing life. However, only a few skeletal adaptations can be found for this. For example , it is currently unknown whether the tail functioned as a grasping organ . The rear caudal vertebrae do not lose length abruptly, which is the case, for example, with primate tails. In contrast, in numerous opossum rats with prehensile tails, the caudal vertebrae shorten more continuously towards the rear. In contrast, the well-developed collarbone allowed the arms to rotate freely. The short and high claws of the hind foot, in turn, were well suited to clinging to the tree bark. The wide articular surfaces on the tarsal bones made the foot very rotatable. However, the lower end of the fused bones of the lower leg (tibia and fibula) may again restrict this flexibility to a certain extent. The parallel rays of the foot in turn point to a corridor in which the foot touched down across its entire width.

Ecological implications

The strong specialization of Heterohyus with a tree-dwelling way of life and a diet of wood-boring or wood-living insects makes it probable that the genus and possibly also other representatives of the Apatemyids occupied the ecological niche of today's woodpeckers . With regard to the current distribution of the finger animal and the striped pouches, it should be noted that neither Madagascar nor New Guinea were colonized by the woodpeckers and that these mammals are therefore being replaced on the two islands. The woodpeckers developed in the course of the Neogene , the appearance of the Apatemyids in the Palaeogene and the lack of fossil records of the birds from the Messel Pit, the Geiseltal and other sites of that time support this view.

Systematics

Possible relationship of the Apatemyidae according to Silcox et al. 2010
  Euarchontoglires  


 Glires


  Apatemyidae  

 Jepsenella


   

 Labidolemur


   

 Apatemys


   

 Carcinella


   

 Heterohyus


   

 Sinclairella








   


 Scandentia


   

 Dermoptera



   

 Primates




Template: Klade / Maintenance / Style

Heterohyus is a genus of the extinct family of Apatemyidae . The representatives of this group are mostly small, insectivore-like mammals, which have been found fossil in today's North America and Europe . In North America, they first appeared in the Paleocene , their last appearance there in the Oligocene . Evidence from Europe is mainly from the Eocene , the animals then disappeared with the onset of the Grande Coupure . Most of the Apatemyidae finds are limited to teeth and dentition remains. The characteristic features of these are the noticeably enlarged and curved incisors, as well as the relatively small molars. The family relationships of the Apatemyidae were unexplained for a long time and are difficult to assess even from today's perspective. Particularly at the beginning of the 20th century, integration into primates or insectivores was often favored. The special position of Apatemyidae expressed William Berryman Scott and Glenn Lowell Jepsen in 1936 with the establishment of the higher taxon of Apatotheria , whose only member they are. Later it could also be anatomically proven that the Apatemyidae do not belong to the primates. Furthermore , there are some similarities to the insectivores, but these mainly concern the more recent forms, for example in the development of the incisors and in individual skull features, while larger deviations are recognizable to the fossil representatives. According to phylogenetic studies from 2010, the Apatemyidae can possibly be assigned to the group of Euarchontoglires . Due to the few defining common anatomical features of the Euarchontoglires - these were defined in 2001 on the basis of genetic similarities - neither the possibility of a closer connection to the Glires (rodents and rabbits) nor to the Euarchonta (primates, pointed squirrels and giant gliders) can be found here be excluded. Within the Apatemyidae, Heterohyus is a more developed representative. The closest relatives can be found in the European form Carcinella from the Upper Eocene and in the North American representative Sinclairella , which still occurred in the late Oligocene.

The following types of heterohyus are recognized:

Different sub-genera are separated within the genus Heterohyus , for example Gervaisyus , which includes the species H. pygmaeus , or Chardinyus with the species H. nanus . The distinction is made on the basis of the expression of certain features on the molars, such as the presence or absence of certain cusps such as the paraconid.

Research history

Paul Gervais
Holotype lower jaw fragment from Bouxwiller, described by Paul Gervais in 1848

The first scientific description of Heterohyus was made in 1848 by Paul Gervais in his work Zoologie et paleontologie françaises . Gervais presented a lower jaw fragment from Bouxwiller in the north-eastern French department of Bas-Rhin and assumed that Heterohyus was related to the wild boar and assumed an omnivorous way of life. He identified Heterohyus armatus as a species . The illustration of the lower jaw that Gervais had published in his first description was reused only a little later by Henri Marie Ducrotay de Blainville . However, he referred him to Arctomys , a modern synonym for the generic name Marmota the marmots . In the second edition of his work Zoologie et paleontologie françaises from 1859, Gervais rejected this assessment of de Blainville and therefore moved Heterohyus back to the pigs. At the same time he established an independent tribe with the "Heteromyines" , which is not recognized. Max Schlosser came to a completely different assessment at the end of the 1880s. Although he included Heterohyax in his very extensive, today not recognized group of Pseudolemuridae, he saw in the form an artifact that was composed of several other genera of different primate forms such as Adapis or Caenopithecus and others.

In the same period as Schlosser, 1890, Henri Filhol analyzed fossil remains from the phosphorite deposits of Quercy in southern France and introduced a species called Necrosorex quercyi based on the remains of the mandible . He suspected the very small form to be related to the shrews , which explains the scientific generic name. In the same year, Ludwig Rütimeyer named Calamodon europaeus using individual teeth fragments from Egerkingen and assigned this very large form to the Taeniodonta , an extinct group of insectivore-like mammals. Hans Georg Stehlin then recognized similarities to Heterohyus during his processing of the Egerkingen finds in 1916 , but set up a new form with the genus Amphichiromys . At the same time he established another representative, Heterochiromys and the species Heterochiromys gracilis from the same site, which is significantly smaller than Amphichiromys europaeus . For both genera and species, Stehlin saw a closer connection to today's finger animals and thus to the group of primates . He also moved Filhol's Necrosorex into the same family , in which he also emphasized the similarities with Heterohyus . All three genera are now considered synonymous with Heterohyus .

In the period that followed, the generic name Heterohyus became increasingly popular. With H. nanus , Teilhard de Chardin described the most frequently documented form in 1922. It is not only known from Quercy, where the evidence comes from, but has also been reported from Spain and England, among others. In addition, all of the skeletons found in the Messel Pit are provisionally assigned to her. The species H. heufelderi received its scientific description in 1930 from Florian Heller based on a lower jaw branch from the Geiseltal . However, some authors classify them as identical to H. gracilis from Egerkingen. The medium-sized form H. morinionensis is based on around a dozen teeth from the Creechbarrow limestone formation and was scientifically introduced in 1986 by Jerry J. Hooker . It is very similar to H. quercyi . In 1975 Bernard Sigé named H. sudrei from Robiac in France. Fifteen years later, H. pygmaeus, another very small form from Quercy, based on a few teeth, followed.

literature

  • Daniela C. Kalthoff, Wighart von Koenigswald and Cornelia Kurz: A new specimen of Heterohyus nanus (Apatemyidae, Mammalia) from the Eocene of Messel (Germany) with unusual soft-part preservation. Courier Forschungsinstitut Senckenberg 252, 2004, pp. 1–12
  • Wighart von Koenigswald, Gregg F. Gunnell, Thomas Lehmann, Kenneth D. Rose and Irina Ruf: Four original, but highly specialized mammals. In: Stephan SK Schaal, Krister T. Smith and Jörg Habersetzer (eds.): Messel - A fossil tropical ecosystem. Senckenberg-Buch 79, Stuttgart, 2018, pp. 223-233

Individual evidence

  1. ↑ a b c d e f g h i Wighart von Koenigswald: The paleobiology of the Apatemyids (Insectivora sl) and the interpretation of the skeletal finds of Heterohyus nanus from the Miotteleocene by Messel near Darmstadt. Palaeontographica Division A, 210 (1-3), 1990, pp. 41-77
  2. ↑ a b c d e f g h Daniela C. Kalthoff, Wighart von Koenigswald and Cornelia Kurz: A new specimen of Heterohyus nanus (Apatemyidae, Mammalia) from the Eocene of Messel (Germany) with unusual soft-part preservation. Courier Forschungsinstitut Senckenberg 252, 2004, pp. 1–12
  3. ↑ a b c d e Wighart von Koenigswald, Gregg F. Gunnell, Thomas Lehmann, Kenneth D. Rose and Irina Ruf: Four original, but highly specialized mammals. In: Stephan SK Schaal, Krister T. Smith and Jörg Habersetzer (eds.): Messel - a fossil tropical ecosystem. Senckenberg-Buch 79, Stuttgart, 2018, pp. 223-233
  4. ↑ a b Wighart von Koenigswald, Kenneth D. Rose, Lance Grande and Robert D. Martin: First apatemyid skeleton from the Lower Eocene Fossil Butte Member, Wyoming (USA), compared to the European apatemyid from Messel, Germany. Palaeontographica Department A 272, 2005, pp. 149-169
  5. ↑ a b c d Wighart von Koenigswald, Irina Ruf and Philip D. Gingerich: Cranial morphology of a new apatemyid, Carcinella sigei n. Gen. N. Sp. (Mammalia, Apatotheria) from the Late Eocene of Southern France. Palaeontographica Department A 288, 2009, pp. 53-91
  6. ↑ a b c Malcolm C. McKenna: Primitive Paleocene and Eocene Apatemyidae (Mammalia, Insectivora) and the Primate-Insectivore Boundary. American Museum Novitates 2160, 1963, pp. 1-39
  7. ^ Philip D. Gingerich and Kenneth D. Rose: Studies on the Paleocene and Early Eocene Apatemyidae (Mammalia, Insectivora). I. Dentition of Clarkforkian Labidolemur kayi. Contributions from the Museum of Paleontology, The University of Michigan 26 (4), 1982, pp. 49-55
  8. ^ Philip D. Gingerich: Studies on the Paleocene and Early Eocene Apatemyidae (Mammalia, Insectivora). II. Labidolemur and Apatemys from the Early Wasatchian of the Clark's Fork Basin, Wyoming. Contributions from the Museum of Paleontology, The University of Michigan 26 (4), 1982, pp. 57-69
  9. ↑ Nicholas J. Czaplewski and Gary S. Morgan: A late-surviving apatemyid (Mammalia: Apatotheria) from the latest Oligocene of Florida, USA. PeerJ 3, 2015, p. E1509; doi: 10.7717 / peerj.1509
  10. ^ A b D. E. Russell, M. Godinot, P. Louis and DE Savage: Apatotheria (Mammalia) de l'Éocèn inférieur de France et de Belgique. Bulletin du Muséum national d'histore naturelle 4e, ser C: 1, 1979, pp. 203–243 ( [1] )
  11. ↑ a b c d J. J. Hooker: Mammals from the Bartonian (Middle / Late Eocene) of the Hampshire Basin, southern England. Bulletin of the British Museum (Natural History) 39 (4), 1986, pp. 191–478 (pp. 327–336)
  12. ^ A b Henri Filhol: Description d'un nouveau genre d'insectivore. Bulletin de la Société philomathique de Paris 8 (1–2), 1890, pp. 174–175 ( [2] )
  13. ↑ a b c Jean Sudre, Bernard Sigé, Jean albert Remy, Bernard Marandat, Jean-Louis Hartenberger, Marc Dodinot and Jean Yves Crochet: Une faune du niveau d'Egerkingen (MP 14; Bartonia Inférieur) dans les phosphorites du Quercy (Sud de la France). Palaeovertebrata 20 (1), 1990, pp. 1-32
  14. ↑ E. Maitre, M. Hugueney, JG Astruc, J.-Y. Crochet, G. Escarguel, M. Godinot, S. Legendre, B. Marandat, C. Mourer-Chauvierế, J.-C. Rage, JA Rếmy, R. Simon-Coinçon, J. Sudre, P. Valette and B. Sigế: Huit nouvelles faunes éocènes et oligocènes des phosphorites du Quercy. In: B. Sigế and T. Pelissie (eds.): 30 Millions d'annees de biodiversite dynamique dans le paleokarst du Quercy. Strata 13, 2006, pp. 113-127
  15. ↑ as SiGe and M. Hugueney: Les micromammifères of gisements à phosphates du Quercy (SW France). In: B. Sigế and T. Pelissie (eds.): 30 Millions d'annees de biodiversite dynamique dans le paleokarst du Quercy. Strata 13, 2006, pp. 207-227
  16. ↑ a b c Bernard Sigé: Les mammifères insectivores des nouvelles collections de Sossís et sites associés (Éocène Superieur, Espagne). Geobios30 (1), 1997, pp. 91-113
  17. ↑ Katerina Vasileiadou, Jerry J. Hooker and Margaret E. Collinson: Paleocommunity reconstruction and accumulation of micromammalian remains (Late Eocene, Southern England). Palaios 24, 2009, pp. 553-567
  18. ^ A b Ludwig Rütimeyer: Overview of the Eocänen fauna of Egerkingen. Negotiations of the Natural Research Society in Basel 9, 1893, pp. 331–362 ( [3] )
  19. ↑ a b Hans Georg Stehlin: The mammals of the Swiss Eocaens. Critical catalog of materials. Treatises of the Swiss Paleontological Society 56, 1916, pp. 1209–1556 (pp. 1434–1508)
  20. ^ A b Paul Gervais: Zoologie et paleontologie françaises (animaux vertébres). Paris, 1848–1852, Tome 1. , p. 163 ( [4] ), Tome 2. , unnumbered ( [5] )
  21. ↑ a b Florian Heller: The mammal fauna of the Middle Eocene lignite in the Geiseltal near Halle a. See the yearbook of the Hallesches Verband for research into Central German mineral resources and their exploitation 9, 1930, pp. 13–41
  22. ↑ Wighart von Koenigswald: Apatemyid skeletons from the Middle Eocene by Messel and their paleobiological statement. Carolinea 45, 1987, pp. 31-35
  23. ↑ Achim H. Schwermannm, M. Wuttke and JA Schultz: Virtopsy of the controlled decomposition of a dormouse Eliomys quercinus as a tool to analyze the taphonomy of Heterohyus nanus from Messel (Eocene, Germany). Palaeobiology and Palaeoenvironments 92, 2012, pp. 29-43
  24. ↑ a b c Mary T. Silcox, Jonathan I. Bloch, Doug M. Boyer and Peter Houde: Cranial anatomy of Paleocene and Eocene Labidolemur kayi (Mammalia: Apatotheria), and the relationships of the Apatemyidae to other mammals. Zoological Journal of the Linnean Society 160, 2010, pp. 773-825
  25. ↑ a b c d Wighart von Koenigswald, Kenneth D. Rose, Lance Grande and Robert D. Martin: The way of life of Eocene mammals (Pantolestidae and Apatemyidae) from Messel (Europe) compared to new skeletal finds from the Fossil Butte Member of Wyoming (North America ). Geological Yearbook Hessen 132, 2005, pp. 43–54
  26. ^ A b Wighart von Koenigswald and HP Schierning: The ecological niche of an extinct group of mammals, the early Tertiary apatemyids. Nature 326, 1987, pp. 595-597
  27. ^ William Diller Matthew: The Carnivora and Insectivora of the Bridger Basin, Middle Eocene. Memoirs of the American Museum of Natural History 9 (4), 1909, pp. 291-576 (pp. 543-549)
  28. ↑ Glenn L. Jepsen: A revision of the American Apatemyidae and the description of a new genus, Sinclairella, from the White River Oligocene of South Dakota. Proceedings of the American Philosophical Society 74 (4), 1934, pp. 287-305
  29. ^ William Berryman Scott and Glenn Lowell Jepsen: The Mammalian Fauna of the White River Oligocene: Part I. Insectivora and Carnivora. Transactions of the American Philosophical Society, New Series 28 (1), 1936, pp. 1-153
  30. ↑ Johannes Hürzeler: About the European Apatemyids. Eclogae Geologicae Helvetiae 42, 1949, p. 485 ( [6] )
  31. ↑ Kenneth D. Rose: The beginning of the age of mammals. Johns Hopkins University Press, Baltimore, 2006, pp. 1-431 (pp. 103-105)
  32. ↑ William J. Murphy, Eduardo Eizirik, Stephen J. O'Brien, Ole Madsen, Mark Scally, Christophe J. Douady, Emma Teeling, Oliver A. Ryder, Michael J. Stanhope, Wilfried W. de Jong and Mark S. Springer : Resolution of the Early Placental Mammal Radiation Using Bayesian Phylogenetics. Science 294, 2001, pp. 2348-2351
  33. ^ Henri Marie Ducrotay de Blainville: Ostéographie ou description iconographique comparée du squelette et du systeme dentaire des mammiferes recents et fossiles. Paris, 1839–1864, unnumbered ( [7] )
  34. ^ Paul Gervais: Zoologie et paleontologie françaises (animaux vertébres). Paris, 1859, pp. 201–201 ( [8] ), Atlas Plate 35 ( [9] )
  35. ↑ Max Schlosser: The monkeys, lemurs, chiropters, insectivors, Marsupials, Creodonts and carnivores of the European Tertiary and their relationships to their living and fossil relatives outside of Europe. Vienna, 1888–1890, pp. 1–492 (pp. 451–452) ( [10] )
  36. ↑ Leigh van Valen: New Paleocene Insectivores and Insectivore classification. Bulletin of the American Museum of Natural History 135, 1967, pp. 217-284
  37. ↑ Malcolm C. McKenna and Susan K. Bell: Classification of mammals above the species level. Columbia University Press, New York, 1997, pp. 1-631 (pp. 212-213)

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