Yarala

Yarala
Temporal occurrence
Upper Oligocene to Middle Miocene
~ 24 to ~ 12 million years
Locations
Australia Kangaroo Well ( Northern Territory ) Riversleigh ( Queensland ) Bullock Creek (Northern Territory)
Systematics
Marsupials (Marsupialia) Australidelphia Nasal pouch (Peramelemorphia) Yaraloidea Yaralidae Yarala
Scientific name of the  superfamily
Yaraloidea
Muirhead , 2000
Scientific name of the  family
Yaralidae
Muirhead, 2000
Scientific name of the  genus
Yarala
Muirhead & Filan , 1995
species
Yarala burchfieldi Muirhead & Filan , 1995 Yarala kida Schwartz , 2006

Yarala is an extinct genus of nasal sacs (Peramelemorphia). Yarala is the only known genus within the monotypic family of the Yaralidae and the superfamily of the Yaraloidea . Fossil finds come from the Upper Oligocene of the Kangaroo Well site ( Northern Territory , Australia ), the Lower Miocene of the Riversleigh fossil deposit in Queensland (Australia) and the Middle Miocene of Bullock Creek (Northern Territory).

Research history and etymology

In 1995, Jeanette Muirhead and Susan L. Filan described a fossil type of nasal sac as Yarala burchfieldi on the basis of several individual teeth, lower jaws and some skull fragments from the freshwater limestone of the "Upper Site" discovery site within the Riversleigh fossil deposit . Five years later, Muirhead supplemented the original diagnosis by analyzing a nearly complete skull from the same site. At the same time, she established a separate family Yaralidae for the genus Yarala in a separate superfamily Yaraloidea.

The genus name Yarala is derived from the word “ yarala ” (“root of the tree”) of the Aboriginal language Waanyi and refers to the original characteristics of the genus. The Artzusatz " burchfieldi " honors Geoffrey Burchfield , a science journalist of the Australian Broadcasting Corporation and council member of the Riversleigh Society.

In 2006 Leah RS Schwartz described similar finds from the somewhat older Kangaroo Well site in the Northern Territory as an independent species Yarala kida . The additional species " kida " ("father") is borrowed from the language of the Mudbra and also refers to the primeval character of the genus.

In 2016 there was another discovery report of some single teeth from the somewhat younger Bullock Creek fossil deposit in the Northern Territory. However, the fossil record was insufficient for an assignment at the species level and was identified as Yarala sp. indet. ("Species indeterminata" = "undefined species").

species

• Yarala burchfieldi Muirhead & Filan , 1995: The type species lived in the Lower Miocene and belonged to the Upper Side local fauna or the local camel sputum fauna of the Riversleigh fossil deposit.
• Yarala kida Schwartz , 2006: This species lived in the late Oligocene as a representative of the local Kangaroo Well fauna in what is now the Northern Territory.
• Yarala sp. indet. Schwartz , 2016: An undetermined species from the Middle Miocene from the Bullock Creek fossil deposit in the Northern Territory.

features

The type species Yarala burchfieldi was smaller than all recent nasal sacs with a skull length of about 30 mm and an estimated average body mass of about 65 g . The body size should have corresponded to that of the recent broad-footed pouch mice .

In addition to some features of the dentition, Yarala burchfieldi is characterized by the Y-shaped forked cheekbones at the contact with the upper jawbone and the continuously narrow nasal bones as a representative of Peramelemorphia. In contrast, Yarala burchfieldi lacks some characteristic features ( synapomorphies ) that are common to all other nasal sacs . The muzzle is comparatively short and the suture between the premaxillary and nasal bone seems to be shorter than that between the nasal bone and maxillary . The nasal bones extend posteriorly beyond the anterior edge of the eye sockets . Helical and squamosal are not in direct contact with each other, but are a large wing of the sphenoid in contact with the parietal bone separated. The infraorbital foramen lies dorsal to the third upper premolar P ³ and not between P ³ and the first upper molar M ¹ , as in all other nasal sacs. The foramen ovale lies between the wing of the sphenoid bone and the temporal bone , but is not accompanied by secondary foramina in this position.

Dentition

Yarala burchfieldi , like all nasal sacs, has a polyprotodontic dentition, which means that there are more than two incisors in the lower jaw . The third under incisor I ₃ shows a two-lobed crown , also typical of nasal sacs .

Further synapomorphies are particularly evident in the morphology of the upper and lower molars. The preparacrista of the first upper molar M ¹ , a ridge that emanates from the paraconus, the anterior and buccal main cusp of the chewing surface , runs posterolabially and ends at the second stylar cusp B. Stylar cusps are a series of secondary cusps of the chewing surface that extend Rise buccally from the main body of the molar from a platform-like extension (“stylar shelf”) of the cingulum (a protruding bead made of tooth enamel). The postparacrista emanating from the paraconus and the premetacrista emanating from the metaconus, the posterior and buccal main cusps of the occlusal surface, unite to form the labial centrocrista, whereby the postparacrista and premetacrista enclose a relatively narrow angle compared to the predatory bag-like .

A cingulid is absent posteriorly in all lower molars. The hypoconulid, a minor hump at the posterior end of the talonid (a deeper lying area of ​​the chewing surface of the lower molars) is low and indistinct. He is lingual positioned almost directly behind the Entoconid and overlaps the anterior Cingulid the next lower molar. A corresponding recess in the cingulid, as it can be found in most of the predatory baggers, is missing in Yarala as in all other nasal sacs. The oblique cristid of the talonid starting from the hypoconid ends at the trigonid, the raised main body of the lower molars, from M ₁ to M ₄ in an increasingly lingual position.

In addition to these nosebuck-typical features, the teeth of Yarala burchfieldi also show features that cannot be assigned to any of the recent nosebuck families. The upper canine C ¹ is greatly elongated and exceeds the crown height of the molars by about four times. A fully formed centrocrista is present on all upper molars. A stunted metaconulus is present on M ³ , while on the anterior molars M ¹ and M ² the postprotocrista runs straight and is connected to the lingual base of the metaconus. The oblique cristid ends labially from an indentation in the metacristid at the lower molars M ₁ and M ₂ and directly at the base of this indentation at M ₃ .

The molars of Yarala kida show essentially the same characteristics as those of Yarala burchfieldi . The stylar cusp B is positioned somewhat more anteriorly than in Yarala burchfieldi and is connected to the preparation acrista in the upper molars M ² and M ³ at the anterolabial corner of the stylar shelf. The lower molars have a strong preentocristide that combines with the postmetacristide to form a kind of “wall” on the border with the talonid. In addition, the entoconid is more blade-shaped and not pointed, as with Yarala burchfieldi .

Systematics

Systematic position of Yarala
Peramelemorphia   Yaralidae  Yarala †     Galadi †     Bulungu †  Crown group  Madju †      Peramelidae  Perameles     Perameles bowensis  †     Isoodon  Peroryctidae  Echymipera     Echymipera clara     Rhynchomeles     Microperoryctes     Peroryctes      Thylacomyidae  Macrotis  Chaeropodidae  Chaeropus  †
simplified after Travouillon & Phillips (2018)

Yarala burchfieldi was determined in the first description simply as a nasal bag of uncertain systematic position (" incertae sedis "). In 2000, Muirhead placed the genus Yarala in its own family Yaralidae and superfamily Yaraloidea, which they compared to all other fossil and recent representatives of the nasal pods known at the time.

Between 2010 and 2014 there were finds of several other fossil nasal pouches from the late Oligocene to the Middle Miocene, which could also not be assigned to the crown group of Peramelemorphia. The finds were grouped into two new genera ( Galadi and Bulungu ) and again characterized as Peramelemorphia "incertae sedis".

Yamila Gurovich and co-authors pointed out in 2014 that the genera Yarala , Galadi and Bulungu show some common features, but they consistently rated these as plesiomorphies . The authors therefore considered it possible that the three genera represent representatives of a paraphyletic parent group and not necessarily form their own clade . For the same reasons, the authors also questioned the validity of the higher taxa Yaralidae and Yaraloidea.

In 2018, Kenny J. Travouillon and Matthew J. Phillips published a phylogenetic analysis of peramelemorphia in which molecular genetic data of recent are combined with morphological features of recent and fossil nasal aspirates. The analysis shows Yarala , Galadi and Bulungu as representatives of a paraphyletic trunk group, with Yarala being the furthest away from the crown group. The genus Madju , which existed almost at the same time, is shown as a crown group representative at the base of a common clade from Peramelidae and Peroryctidae .

The analysis also provided indications that the Peroryctidae, next to the Peramelidae, the Thylacomyidae and the Chaeropodidae , which only became extinct in the 20th century , are to be rated as the fourth independent family within the crown group of the nasal sacs.

Paleecology

Based on the small body size and the morphology of the teeth, Yarala assumes a predominantly or exclusively insectivorous diet. In contrast, recent nasal aspirators have a largely omnivorous diet . Yarala probably occupied an ecological niche comparable to that of the small-stature representatives of the recent predatory pouches , such as the Queensland broad-footed pouch ( Antechinus godmani ) or the black-tailed New Guinea pouch ( Murexia melanurus ).

The freshwater carbonates from the Riversleigh fossil site were deposited in lakes and caves in a karst area . The localities of Yarala burchfieldi can be (the earlier breakdown by Archer = "System B" "B Faunenzone" et al. , 1989) associate within the fossil deposit, for a rain forest habitats is assumed to be habitat.

The ulta limestone of the Kangaroo Well local fauna, however, was deposited in a fluvial system. It can be called Calcret and allows some conclusions about the habitat of Yarala kida . The sedimentology and paleontology of the Ulta Limestone suggest a temperate but relatively dry climate with an annual mean temperature of 14–20 ° C and an average annual rainfall of probably less than 600 mm. These conditions are not suitable for forests with a largely closed canopy, so that a more open habitat than a habitat for Yarala kida can be assumed.

Individual evidence

1. ↑ ^{a b c d e f g h i} J. Muirhead & SL Filan: Yarala burchfieldi, a plesiomorphic bandicoot (Marsupialia, Peramelemorphia) from Oligo-Miocene deposits of Riversleigh, northwestern Queensland. In: Journal of Paleontology , Volume 69, Number 1, 1995, pp. 127-134, doi : 10.1017 / S0022336000026986 .
2. ↑ ^{a b c} J. Long, M. Archer, T. Flannery & S. Hand: Prehistoric Mammals of Australia and New Guinea - One Hundred Million Years of Evolution . Johns Hopkins University Press, Baltimore / London, 2002, ISBN 0-8018-7223-5 , pp. 73ff, ( reading sample ).
3. ↑ ^{a b c d e f g h i j k} J. Muirhead: Yaraloidea (Marsupialia, Peramelemorphia), a new superfamily of marsupial and a description and analysis of the cranium of the Miocene Yarala burchfieldi. In: Journal of Paleontology , Volume 74, Number 3, 2000, pp. 512-523, ( digitized ).
4. ↑ ^{a b c} LRS Schwartz: A new species of bandicoot from the Oligocene of northern Australia and implications of bandicoots for correlating Australian Tertiary mammal faunas. In: Palaeontology , Volume 49, Number 5, 2006, pp. 991-998, doi : 10.1111 / j.1475-4983.2006.00584.x .
5. ↑ ^{a b} LRS Schwartz: A revised faunal list and geological setting for Bullock Creek, a Camfieldian site from the Northern Territory of Australia. In: Memoirs of Museum Victoria , Volume 74, 2016, pp. 263–290, ( digitized version ).
6. ↑ ^{a b c d} Y. Gurovich, KJ Travouillon, RMD Beck, J. Muirhead & M. Archer: Biogeographical implications of a new mouse-sized fossil bandicoot (Marsupialia: Peramelemorphia) occupying a dasyurid-like ecological niche across Australia. In: Journal of Systematic Palaeontology , Volume 12, Number 3, 2014, pp. 265-290, ( digitized ).
7. ↑ ^{a b} PS Ungar: Teeth: A Very Short Introduction. Oxford University Press, Gosport, 2014, ISBN 978-0-19-967059-8 , pp. 12ff, ( excerpt ).
8. ↑ St. Wroe: A Reexamination of Proposed Morphology-Based Synapomorphies for the Families of Dasyuromorphia (Marsupialia). I. Dasyuridae. In: Journal of Mammalian Evolution , Volume 4, Number 1, 1997, pp. 19-52, ( digitized version ).
9. ↑ ^{a b c} KJ Travouillon & MJ Phillips: Total evidence analysis of the phylogenetic relationships of bandicoots and bilbies (Marsupialia: Peramelemorphia): reassessment of two species and description of a new species. In: Zootaxa , Volume 4378, Number 2, 2018, pp. 224-256, ( digitized ).
10. ↑ KJ Travouillon, Y. Gurovich, RMD Beck & J. Muirhead: An exceptionally well-preserved short-snouted bandicoot (Marsupialia; Peramelemorphia) from Riversleigh's Oligo-Miocene deposits, northwestern Queensland, Australia. In: Journal of Vertebrate Paleontology , Volume 30, Number 5, 2010, pp. 1528-1546, ( digitized ).
11. Jump up ↑ KJ Travouillon, Y. Gurovich, M. Archer, SJ Hand & J. Muirhead: The genus Galadi: three new bandicoots (Marsupialia, Peramelemorphia) from Riversleigh's Miocene deposits, northwestern Queensland, Australia. In: Journal of Vertebrate Paleontology , Volume 33, Number 1, 2013, pp. 153-168, ( digitized ).
12. ↑ M. Archer, H. Godthelp, SJ Hand & D. Megirian: Fossil Mammals of Riversleigh, Northwestern Queensland: Preliminary Overview of Biostratigraphy, Correlation and Environmental Change. In: Australian Zoologist , Volume 25, Number 2, 1989, pp. 29-65, ( digitized ).
13. ↑ KJ Travouillon, S. Legendre, M. Archer & SJ Hand: Palaeoecological analyzes of Riversleigh's Oligo-Miocene sites: Implications for Oligo-Miocene climate change in Australia. In: Palaeogeography, Palaeoclimatology, Palaeoecology , Volume 276, 2009, pp. 24-37, ( digitized version ).
14. ^ D. Megirian, P. Murray, L. Schwartz & C. von der Borch: Late Oligocene Kangaroo Well Local Fauna from the Ulta Limestone (new name), and climate of the Miocene oscillation across central Australia. In: Australian Journal of Earth Sciences , Volume 51, 2004, pp. 701-741, ( digitized ).

Remarks

1. ↑ Morphological features of the lower molars are generally identified with the ending "-id". A main cusp ("conus") of the upper molars is accordingly called a "conid", a secondary cusp ("conulus") as a "conulid", a ridge ("crista") as a "cristid" and the "cingulum" as a "cingulid" .