Ericiolacerta

Last updated

Ericiolacerta
Temporal range: Early Triassic
~251–249  Ma
Ꞓ
O
S
D
C
P
T
J
K
Pg
N
↓
Ericiolacerta BW.jpg
Ericiolacerta parva
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Clade:† Therocephalia
Family:† Ericiolacertidae
Genus:† Ericiolacerta
Watson, 1931
Species:
†E. parva
Binomial name
†Ericiolacerta parva
Watson, 1931
Ericiolacerta EriciolacertaDB.jpg
Ericiolacerta

Ericiolacerta is an extinct genus of small therocephalian therapsids from the early Triassic of South Africa and Antarctica. [1] [2] Ericiolacerta, meaning "hedgehog lizard" (from the Latin ericius, "hedgehon" and lacerta, "lizard"), [3] was named by D.M.S. Watson in 1931. [1] The species E. parva is known from the holotype specimen which consists of a nearly complete skeleton found in the Lystrosaurus Assemblage Zone within the Katberg Formation of the Beaufort Group in South Africa, [1] [3] and from a partial jaw found in the Lower Triassic Fremouw Formation in Antarctica. [2] Ericiolacerta was around 20 centimetres (7.9 in) in length, with long limbs and relatively small teeth. [1] It probably ate insects and other small invertebrates. The therocephalians – therapsids with mammal-like heads – were abundant in Permian times, but only a few made it into the Triassic. Ericiolacerta was one of those. It is possible that they gave rise to the cynodonts, the only therapsid group to survive into post-Triassic times. Cynodonts gave rise to mammals.

Contents

Discovery

The Ericiolacerta holotype specimen Ericiolacerta parva was discovered in 1931 in the Katberg Formation of the Beaufort Group near Harrismith, Free State in South Africa and described by Professor David Meredith Seares Watson in an article for the Zoological Society of London. [1] [3] It was discovered by A. W. Putterill within a cornerstone block of limestone from the shales of the Lystrosaurus Assemblage Zone, placing it between ~251-249 Ma during the early Triassic. [1] The specimen consisted of a nearly complete skeleton with a slightly crushed skull. Watson described it as being closely related to the Therocephalian Scaloposaurus based on their skull morphology but as a new member of the family Scaloposauridae founded by Broom in 1914 based on differences in its dentition and jaw structure. [1] This classification was later changed as this family was invalidated and many of its members were moved into the superfamily Baurioidea. [4]

Another specimen was discovered in 1971 in the Lower Triassic Fremouw Formation of the Transantarctic Mountains in Antarctica near the McGregor and Shackleton glaciers and described in 1981 by Edwin H. Colbert and James W. Kitching. [2] They described an associated mandibular ramus and pterygoids, and the hindlimbs of an Ericiolacerta parva specimen based on similarities in jaw structure, dentition, and foot structure to the Watson specimen from Africa. [2] This diagnosis was later revised in Huttenlocker & Sidor (2012), in which the hind limbs were reevaluated as belonging to an indeterminate Eutherocephalian, and the mandibular ramus and pterygoids were confirmed as likely belonging to Ericiolacerta parva. [5] The discovery of this species and others such as Lystrosaurus within both the African Lystrosaurus zone and the Antarctic Fremouw Formation lends more evidence to the fact that these continents were previously congruent as presented in Elliot et al. (1970). [2] [6] [7]

Description

Ericiolacerta parva was described as a small, fossilized reptile preserved extremely well, despite the skull being partially crushed before it was buried, resulting in distortion of the occipital, otic, and mandibular bones, as well as the loss of part of the premaxillae and zygoma. The specimen is also missing twelve vertebrae from its midsection, but besides these the skeleton is completely preserved. [1] The curled position of the skeleton is similar to that assumed by many small mammals when they die, and the displacement of the bones was determined to be as a result of the movement and rotting of still-attached skin. The cause of the fractured skull was attributed to a larger animal likely stepping on the body. [1] The specimen's total length from snout to the hind end of the pelvis was measured to be 17 centimetres (6.7 in). [1] It was notable for the small size and irregularity of its teeth, the reduction/lack of canine teeth, the large size of its head and pectoral girdle compared to its relatively small pelvic girdle, and its long, slender limbs. [1] By comparison, the Antarctic mandible from 1981 was described as being from a larger Ericiolacerta parva specimen, but maintained the small tooth size, irregularity, and reduced canines seen in the dentition of the African specimen. [2] Both specimens demonstrate a slender dentary with a smooth, rounded ventral margin, which was determined by Huttenlocker & Sidor (2012) to be a compelling apomorphy in diagnosing the species. [2] [5] The presence of a tuber calcis on the posterior side of the calcaneum in the specimen was revised as a poor character in assigning Ericiolacertaparva and was used to reevaluate the hindlimbs of the Antarctic specimen as belonging to an indeterminate Eutherocephalian. [5]

Paleobiology

As a member of the Therocephalia sub-order within the Theriodont group, Ericiolacerta would have had much more in common with the cynodonts which gave rise to mammals than with other Theriodonts such as Gorgonopsids. Some evidence has suggested Therocephalia may represent a polyphyletic group with some species being more closely related to cynodonts than others, and a uniting clade called Eutheriodontia has been proposed. [8] Most modern studies, however, consider Therocephalia to be a monophyletic group. Ericiolacerta shared many traits common in more basal Theriodonts as well as in mammals. Their small size similar to cynodonts may imply a burrowing lifestyle, and unlike other Therocephalians they possessed a secondary palate which may have aided in breathing while eating or in endothermy. [9] [10] The skull also possessed wide, slender zygomatic arches and postorbitals which failed to connect with the zygoma, all features also present in more derived cynodonts which likely aided in muscle attachment for chewing. [9] Conversely, unlike other Theriodonts Ericiolacerta did not possess a free upstanding coronoid process on the dentary which would also have aided in connecting muscle fibers. [9] It also did not experience the reduction of the lumbar ribs seen in members of Cynodontia, which is hypothesized to have evolved to increase their aerobic capacity. This would suggest that like other basal Theriodonts Ericiolacerta did not possess a transverse diaphragm. [1] [11] The holotype fossil described by Watson had its sternum only partially exposed, making determining if Ericiolacerta had evolved the segmented sternebrae seen in some Gorgonopsians difficult. [1] [12] This synapomorphy has been linked to evolutionary developments in locomotion and respiration towards the "mammalian-type" condition. [12] This, combined with the long length of its limbs relative to its size implies Ericiolacerta had a more sprawling stance and reptilian gait than more derived cynodonts. [1] Little holes in the snout area of the skull suggest that perhaps the snout had developed sense organs, like whiskers. A palate in the roof of the mouth separated the breathing passage from the eating area. This suggests an efficient eating mechanism that may indicate a warm-blooded lifestyle.

Paleoenvironment

Ericiolacerta parva appears in the Lystrosaurus Biozone in South Africa, as well as the lower Fremouw in Antarctica during the Triassic. [7] The Antarctic environment during the Triassic in the Fremouw Formation has been reconstructed containing dense forested areas located along riverbanks and floodplains. These forests contained a dense layer of Dicroidium leaflitter and existed as far south as ~70-75°. [13] Analysis of fossilized trees and plant matter by Cúneo et al. (2003) determined that Antarctica experienced very favorable seasons of plant growth and described evidence of a cooling climate during the Late Triassic which the Antarctic ecosystem would be the first to respond to due to its high latitude. These conditions created an environment that was ripe for speciation, resulting in an explosion of diversity in the region. [13] Studies of species such as Ericiolacerta which have been found in both the Karoo Basin of South Africa and the Fremouw Formation in Antarctica have determined that several species first appeared in Antarctica before later appearing in South Africa, providing evidence towards Antarctica being a hotspot for speciation. [8] [7] In the early Triassic, African flora was rich. The vegetation was used as shelter and food for numerous insects Ericiolacerta fed on. [14]

Classification

Ericiolacerta belongs to the order Therocephalia within the clade Eutherocephalia, and placed in the superfamily Baurioidea in the Ericiolacertidae family. [15] [4] It was initially classified within the now-obsolete group Scaloposauria which is now considered to likely represent juvenile forms of various therocephalians, at which point Ericiolacerta was reclassified within Baurioidea. [4] Below is a cladogram of Baurioidea adapted from Huttenlocker (2009) and Huttenlocker & Sidor (2012). [16] [5]

Baurioidea  

Ictidosuchus

Ictidosuchops

Ictidosuchoides

Regisaurus

Scaloposaurus

Lycideops

Tetracynodon

Ericiolacerta

Bauriidae

See also

Related Research Articles

<span class="mw-page-title-main">Therapsid</span> Clade of tetrapods including mammals

A therapsid is a member of the clade Therapsida which is a major group of eupelycosaurian synapsids that includes mammals and their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, as opposed to the sprawling posture of many reptiles and salamanders.

<span class="mw-page-title-main">Cynodont</span> Clade of therapsids

Cynodonts are eutheriodont therapsids belonging to the clade Cynodontia that first appeared in the Late Permian, and extensively diversified after the Permian–Triassic extinction event. Cynodonts occupied a variety of ecological niches, both as carnivores and as herbivores. Mammals are cynodonts, as are their extinct ancestors and close relatives (Mammaliaformes), having evolved from advanced probainognathian cynodonts during the Late Triassic. All other cynodont lines went extinct, with the last known non-mammaliaform cynodont group, the Tritylodontidae, having its youngest records in the Early Cretaceous.

<i>Lystrosaurus</i> Genus of Late Permian and Early Triassic dicynodont therapsids

Lystrosaurus is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs. It lived in what is now Antarctica, India, China, Mongolia, European Russia and South Africa. Four to six species are currently recognized, although from the 1930s to 1970s the number of species was thought to be much higher. They ranged in size from that of a small dog to 8 feet long.

<span class="mw-page-title-main">Therocephalia</span> Extinct order of therapsids

Therocephalia is an extinct clade of eutheriodont therapsids from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. This relationship takes evidence in a variety of skeletal features.

<span class="mw-page-title-main">Theriodontia</span> Clade of therapsids

The theriodonts are a major group of therapsids which appeared during the Middle Permian and which includes the gorgonopsians and the eutheriodonts, itself including the therocephalians and the cynodonts.

<i>Euchambersia</i> Extinct genus of therapsid from Late Permian South Africa

Euchambersia is an extinct genus of therocephalian therapsids that lived during the Late Permian in what is now South Africa and China. The genus contains two species. The type species E. mirabilis was named by paleontologist Robert Broom in 1931 from a skull missing the lower jaw. A second skull, belonging to a probably immature individual, was later described. In 2022, a second species, E. liuyudongi, was named by Jun Liu and Fernando Abdala from a well-preserved skull. It is a member of the family Akidnognathidae, which historically has also been referred by as the synonymous Euchambersiidae.

<i>Moschorhinus</i> Genus of synapsid from late Permian and early Triassic South Africa

Moschorhinus is an extinct genus of therocephalian in the family Akidnognathidae with only one species: M. kitchingi. It was a carnivorous synapsid which has been found in the Late Permian to Early Triassic of the South African Karoo Supergroup. It was a large carnivore, reaching 1.5 m (4.9 ft) in total body length with the largest skull comparable to that of a lion in size. It had a broad, blunt snout which bore long, straight canines. It appears to have replaced the gorgonopsids ecologically, and hunted much like a big cat. While most abundant in the Late Permian, it survived a little after the Permian Extinction, though these Triassic individuals had stunted growth.

<i>Theriognathus</i> Extinct genus of therapsids from late Permian South Africa and Tanzania

Theriognathus is an extinct genus of therocephalian therapsid belonging to the family Whaitsiidae, known from fossils from South Africa, Zambia, and Tanzania. Theriognathus has been dated as existing during the Late Permian. Although Theriognathus means mammal jaw, the lower jaw is actually made up of several bones as seen in modern reptiles, in contrast to mammals. Theriognathus displayed many different reptilian and mammalian characteristics. For example, Theriognathus had canine teeth like mammals, and a secondary palate, multiple bones in the mandible, and a typical reptilian jaw joint, all characteristics of reptiles. It is speculated that Theriognathus was either carnivorous or omnivorous based on its teeth, and was suited to hunting small prey in undergrowth. This synapsid adopted a sleek profile of a mammalian predator, with a narrow snout and around 1 meter long. Theriognathus is represented by 56 specimens in the fossil record.

<i>Regisaurus</i> Genus of therapsids from the Early Triassic of South Africa

Regisaurus is an extinct genus of small carnivorous therocephalian. It is known from a single described species, the type species Regisaurus jacobi, from the Early Triassic Lystrosaurus Assemblage Zone of South Africa, although at least one undescribed species is also known.

<i>Glanosuchus</i> Extinct genus of therapsids

Glanosuchus is a genus of scylacosaurid therocephalian from the Late Permian of South Africa. The type species G. macrops was named by Robert Broom in 1904. Glanosuchus had a middle ear structure that was intermediate between that of early therapsids and mammals. Ridges in the nasal cavity of Glanosuchus suggest it had an at least partially endothermic metabolism similar to modern mammals.

Promoschorhynchus is a genus of akidnognathid therocephalians from the Late Permian and Early Triassic of South Africa. Unlike many other therapsids, Promoschorhynchus survived the Permian-Triassic extinction event.

Rhigosaurus glacialis is a species of therocephalian therapsid. Its fossilized remains have been found in the Fremouw Formation of Antarctica. Part of a juvenile skull was found near Mount Kenyon, Antarctica. The holotype of the partial skull shows evidence of promiment upper and lower canine teeth.

<i>Kombuisia</i> Extinct genus of dicynodonts

Kombuisia is a genus of dicynodont from Early to Middle Triassic of South Africa and Antarctica. Two species were described for the genus: Kombuisia frerensis (type) and Kombuisia antarctica.

<span class="mw-page-title-main">Akidnognathidae</span> Extinct family of therapsids

Akidnognathidae is an extinct family of therocephalian therapsids from the Late Permian and Early Triassic of South Africa, Russia and China. The family includes many large-bodied therocephalians that were probably carnivorous, including Moschorhinus and Olivierosuchus. One akidnognathid, Euchambersia, may even have been venomous. Akidnognathids have robust skulls with a pair of large caniniform teeth in their upper jaws. The family is morphologically intermediate between the more basal therocephalian group Scylacosauridae and the more derived group Baurioidea.

<span class="mw-page-title-main">Scylacosauridae</span> Extinct family of therapsids

Scylacosauridae is an extinct family of therocephalian therapsids. Scylacosaurids lived during the Permian period and were among the most basal therocephalians. The family was named by South African paleontologist Robert Broom in 1903. Scylacosaurids have long snouts and unusual saber-like canine teeth.

<span class="mw-page-title-main">Baurioidea</span> Extinct superfamily of therapsids

Baurioidea is a superfamily of therocephalian therapsids. It includes advanced therocephalians such as Regisaurus and Bauria. The superfamily was named by South African paleontologist Robert Broom in 1911. Bauriamorpha, named by D. M. S. Watson and Alfred Romer in 1956, is a junior synonym of Baurioidea.

<span class="mw-page-title-main">Bauriidae</span> Extinct family of therapsids

Bauriidae is an extinct family of therocephalian therapsids. Bauriids were the latest-surviving group of therocephalians after the Permian–Triassic extinction event, going extinct in the Middle Triassic. They are among the most advanced eutherocephalians and possess several mammal-like features such as a secondary palate and wide postcanine teeth at the back of the jaws. Unlike other therocephalians, bauriids were herbivorous. They were also smaller than earlier members of the group. Two subfamilies are classified within Bauriidae: Nothogomphodontinae and Bauriinae.

<i>Blattoidealestes</i> Extinct genus of therapsid from Middle-Permian South Africa

Blattoidealestes is an extinct genus of therocephalian therapsid from the Middle Permian of South Africa. The type species Blattoidealestes gracilis was named by South African paleontologist Lieuwe Dirk Boonstra from the Tapinocephalus Assemblage Zone in 1954. Dating back to the Middle Permian, Blattoidealestes is one of the oldest therocephalians. It is similar in appearance to the small therocephalian Perplexisaurus from Russia, and may be closely related.

Homodontosaurus is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species Homodontosaurus kitchingi was named by South African paleontologist Robert Broom in 1949. Broom based his description on a small skull found in the Cistecephalus Assemblage Zone near Graaff-Reinet. The skull is very small, at about 55 millimetres (2.2 in) long and 20 millimetres (0.79 in) wide. Homodontosaurus has large eye sockets and an elongated snout. The lower jaw is long, thin, and curved. Numerous small teeth line the upper jaw and are long, pointed, and round in cross-section.

Lycideops is an extinct genus of therocephalians from the Late Permian of South Africa. The type species is Lycideops longiceps, named in 1931 by South African paleontologist Robert Broom. Fossils of Lycideops come from the Dicynodon Assemblage Zone of the Beaufort Group. Lycideops is a member of the family Lycideopidae. Like other lycideopids, Lycideops has a long snout.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Watson, D.M.S. (1931). "On the skeleton of a bauriamorph reptile". Proceedings of the Zoological Society of London. 101 (3): 1163–1205. doi:10.1111/j.1096-3642.1931.tb01056.x.
  2. 1 2 3 4 5 6 7 Colbert, Edwin H.; Kitching, James W. (1981). "Scaloposaurian reptiles from the Triassic of Antarctica". American Museum Novitates (2709): 1–22.
  3. 1 2 3 "Ericiolacerta". Paleofile. Retrieved 5 April 2022.
  4. 1 2 3 Kemp, T. S. (1986-09-02). "The skeleton of a baurioid therocephalian therapsid from the Lower Triassic (LystrosaurusZone) of South Africa". Journal of Vertebrate Paleontology. 6 (3): 215–232. doi:10.1080/02724634.1986.10011617. ISSN   0272-4634.
  5. 1 2 3 4 Huttenlocker, Adam K.; Sidor, Christian A. (March 2012). "Taxonomic Revision of Therocephalians (Therapsida: Theriodontia) from the Lower Triassic of Antarctica". American Museum Novitates (3738): 1–19. doi:10.1206/3738.2. ISSN   0003-0082. S2CID   55745212.
  6. ↑ Elliot, D. H.; Colbert, E. H.; Breed, W. J.; Jensen, J. A.; Powell, J. S. (1970-09-18). "Triassic Tetrapods from Antarctica: Evidence for Continental Drift". Science. 169 (3951): 1197–1201. doi:10.1126/science.169.3951.1197. ISSN   0036-8075. PMID   17815934. S2CID   10995542.
  7. 1 2 3 Sidor, Christian A.; Damiani, Ross; Hammer, William R. (2008-09-12). "A new Triassic temnospondyl from Antarctica and a review of Fremouw Formation biostratigraphy". Journal of Vertebrate Paleontology. 28 (3): 656–663. doi:10.1671/0272-4634(2008)28[656:anttfa]2.0.co;2. ISSN   0272-4634. S2CID   131582010.
  8. 1 2 Abdala, Fernando; Rubidge, Bruce S.; van den Heever, Juri (2008-07-15). "The oldest therocephalians (Therapsida, Eutheriodontia) and the early diversification of Therapsida". Palaeontology. 51 (4): 1011–1024. doi: 10.1111/j.1475-4983.2008.00784.x . ISSN   0031-0239.
  9. 1 2 3 Watson, D.M.S.; Romer, A.S. (1956). "A classification of therapsid reptiles". Bulletin of the Museum of Comparative Zoology. 114 (2): 37–89.
  10. ↑ Damiani, Ross; Modesto, Sean; Yates, Adam; Neveling, Johann (2003-08-22). "Earliest evidence of cynodont burrowing". Proceedings of the Royal Society of London. Series B: Biological Sciences. 270 (1525): 1747–1751. doi:10.1098/rspb.2003.2427. ISSN   0962-8452. PMC   1691433 . PMID   12965004.
  11. ↑ Hillenius, Willem J.; Ruben, John A. (2004-07-26). "The Evolution of Endothermy in Terrestrial Vertebrates: Who? When? Why?". Physiological and Biochemical Zoology. 77 (6): 1019–1042. doi:10.1086/425185. ISSN   1522-2152. PMID   15674773. S2CID   29300018.
  12. 1 2 Bendel, Eva-Maria; Kammerer, Christian F.; Luo, Zhe-Xi; Smith, Roger M. H.; Fröbisch, Jörg (2022-08-05). "The earliest segmental sternum in a Permian synapsid and its implications for the evolution of mammalian locomotion and ventilation". Scientific Reports. 12 (1): 13472. doi:10.1038/s41598-022-17492-6. ISSN   2045-2322. PMC   9356055 . PMID   35931742.
  13. 1 2 Cúneo, N.Rubén; Taylor, Edith L.; Taylor, Thomas N.; Krings, Michael (September 2003). "In situ fossil forest from the upper Fremouw Formation (Triassic) of Antarctica: paleoenvironmental setting and paleoclimate analysis". Palaeogeography, Palaeoclimatology, Palaeoecology. 197 (3–4): 239–261. doi:10.1016/s0031-0182(03)00468-1. ISSN   0031-0182.
  14. ↑ The Complete Guide to Dinosaurs and Prehistoric Reptiles, Chris McNab and prof. Michael Benton, Marshall Editions, London 2006.
  15. ↑ Watson, D. M. S. (September 1931). "55. On the Skeleton of a Bauriamorph Reptile". Proceedings of the Zoological Society of London. 101 (3): 1163–1205. doi:10.1111/j.1096-3642.1931.tb01056.x. ISSN   0370-2774.
  16. ↑ HUTTENLOCKER, ADAM (December 2009). "An investigation into the cladistic relationships and monophyly of therocephalian therapsids (Amniota: Synapsida)". Zoological Journal of the Linnean Society. 157 (4): 865–891. doi: 10.1111/j.1096-3642.2009.00538.x . ISSN   0024-4082.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.