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Lydekkerinidae és un família extinta de temnospòndils que van viure al començament del període Triàsic en el que avui és Sud-àfrica, Groenlàndia, Rússia, Austràlia, Tasmània, l'Índia i l'Antàrtida.
Lydekkerinidae és un família extinta de temnospòndils que van viure al començament del període Triàsic en el que avui és Sud-àfrica, Groenlàndia, Rússia, Austràlia, Tasmània, l'Índia i l'Antàrtida.
Lydekkerinidae is a family of stereospondyl temnospondyls that lived in the Early Triassic period. During this time period, lydekkerinids were widely distributed, with putative remains reported from Russia, Greenland, India, South Africa, Madagascar, Australia, and Antarctica.[1][2][3][4][5][6] In contrast to most other stereospondyls, lydekkerinids were relatively small-bodied (most with skulls less than 10 cm in length). The type genus is Lydekkerina, the namesake of the family and the best-known lydekkerinid.
The identification of features shared among lydekkerinids (synapomorphies) necessarily varies depending on which taxa are considered to belong to this group (see further in next section). In the most expansive concept, the family includes the eponymous Lydekkerina (and junior synonyms like 'Broomulus' and 'Limnoiketes'), Eolydekkerina from South Africa, Deltacephalus from Madagascar, Luzocephalus from Russia and Greenland (which includes the 'Aquiloniferus' of Bjerring (1999),[7] which is largely refuted by other workers), Chomatobatrachus from Australia, and indeterminate records from Antarctica and India ('Indobenthosuchus' and 'Cryobatrachus'). However, most previous workers have not considered all of these taxa to be true lydekkerinds;[4] in particular, the affinities of non-South African taxa have been challenged.
For example, Schoch & Milner (2000) considered all nominal lydekkerinids to belong to this family and listed featured like longitudinally oval, unpaired anterior palatal openings, with a pointed posterior end; and a broad and laterally extensive postorbital and prefrontal as synapomorphies.[3] Jeannot et al. (2006) considered most nominal lydekkerinids to indeed be lydekkerinids except for Deltacephalus and the indeterminate records.[4] They list features like a step-shaped contact between the nasal and prefrontal; indentation of anterolateral margin of interpterygoid vacuity; and a straight cheek margin when viewed in occipital view as synapomorphies. Conversely, Hewison (2007) did not consider Chomatobatrachus or Luzocephalus to be lydekkerinids and therefore listed a different set of features, such as palatine lacking denticles, but having an elongated postero-mesial process extending behind the most anterior ectopterygoid tooth; ectopterygoid lacking denticles; and septomaxillary with an ornamented roofing portion and an unornamented, plate- like intranarial portion.[8] Many of Hewison's features (of which there are more than two dozen) are not synapomorphies but rather are part of a unique combination of features or are symplesiomorphies, and they are not mutually exclusive with the autapomorphies of other workers.
Most recently, it has also been suggested that another small-bodied Early Triassic clade, Lapillopsidae, might nest within Lydekkerinidae, rendering the latter paraphyletic.[9] If so, this would introduce further uncertainty regarding diagnostic features of Lydekkerinidae.
Lydekkerinids are usually classified as basal stereospondyls. Schoch and Milner (2000) placed them in the clade Rhytidostea along with brachyopoids and rhytidosteids,[3] but this broader grouping is not widely employed today given the higher nesting position of brachyopoids and the uncertain position and monophyly of rhytidosteids.[10][11][12][13] Lydekkerinidae was also sometimes historically placed within the largely defunct Rhinesuchoidea[14][15] or within the still valid Capitosauroidea or Capitosauria,[2] but this too has not been supported by more recent work. Most phylogenetic studies that sampled only certain nominal lydekkerinids within a larger temnospondyl sample have found lydekkerinids to be paraphyletic or polyphyletic.[16][12][13][17][9] Furthermore, no complete phylogenetic analysis of all nominal lydekkerinids that would support monophyly in at least a restricted framework has been formally published.[18] Luzocephalus, which would be the largest of the lydekkerinids with a skull length over 15 cm,[19] has often been found to be more closely related to a family called Trematosauridae, such as in the study by Yates and Warren (2000). Chomatobatrachus has also been frequently dissociated from other nominal lydekkerinids.[2][8] Below is a cladogram from Yates and Warren (2000) showing the polyphyly:[10]
Stereospondyli Capitosauria TrematosauriaThe phylogenetic analysis of Damiani (2001) resulted in a monophyletic Lydekkerinidae, although it was only weakly supported and included what is now recognized as the small-bodied Early Triassic capitosaur Edingerella madagascariensis. Below is a cladogram from that analysis:[20]
Stereospondyli Rhinesuchidae Lydekkerinidae"Parotosuchus" madagascarensis
Eolydekkerina magna, of the early Triassic of South Africa
Lyddekerina huxleyi, of the early Triassic of South Africa and Australia
Cryobatrachus kitchingi, of the early Triassic of Antarctica
Lydekkerinidae is a family of stereospondyl temnospondyls that lived in the Early Triassic period. During this time period, lydekkerinids were widely distributed, with putative remains reported from Russia, Greenland, India, South Africa, Madagascar, Australia, and Antarctica. In contrast to most other stereospondyls, lydekkerinids were relatively small-bodied (most with skulls less than 10 cm in length). The type genus is Lydekkerina, the namesake of the family and the best-known lydekkerinid.
Lydekkerinidae es un familia extinta de temnospóndilos que vivieron a comienzos del período Triásico en lo que hoy es Sudáfrica, Groenlandia, Rusia, Australia, Tasmania, la India y la Antártida. El género tipo es Lydekkerina, que le da su nombre a la familia y es también el mejor conocido entre los lydekkerínidos.
Los lydekkerínidos tiene una distintiva combinación de características. Sus sinapomorfias, o rasgos únicos, incluyen un contacto entre el hueso nasal y el hueso prefrontal en forma de escalón, márgenes laterales interdentados de las cavidades interpterigoides (dos grandes agujeros en el paladar), y márgenes rectos en la mejilla cuando el cráneo es visto desde detrás. Otras características incluyen un hueso frontal que no toca el borde de las órbitas oculares y crestas en el hueso pterigoides. Surcos sensores (canales que corrían a lo largo de la superficie del cráneo) que están presentes en muchos temnospóndilos son apenas visibles en los cráneos de los lydekkerínidos. El surco infraorbital, un canal que corre bajo los ojos y las fosas nasales, tiene una distintiva curva a lo largo de su longitud. Pequeñas protuberancias denominadas dentículos cubren la mayor parte del paladar.[1]
Los lydekkerínidos son clasificados usualmente como estereospóndilos basales. Schoch y Milner (2000) los situaron en el clado Rhytidostea junto con los braquiopoides y los ritidostéidos.[2] Algunos estudios filogenéticos de los lydekkerínidos han encontrado que son polifiléticos. Estos estudios incluyen a los taxones lydekkerínidos tradicionales Lydekkerina y Luzocephalus, y a veces a Deltacephalus. Se ha encontrado que Luzocephalus está más cercanamente relacionado con una familia llamada Trematosauridae, mientras que Lydekkerina permanece en una posición basal entre los estereospóndilos. Yates y Warren (2000) encontraron que Lydekkerina es un miembro basal del clado de estereospóndilos Capitosauria, mientras que Luzocephalus cae en el clado Trematosauria. A continuación un cladograma basado en Yates y Warren (2000) mostrando la polifilia:[3]
Stereospondyli Capitosauria TrematosauriaEl análisis filogenético de Damiani (2001) da como resultado un clado Lydekkerinidae monofilético, aunque con un débil soporte. A continuación un cladograma basado en ese análisis:[4]
Stereospondyli Rhinesuchidae Lydekkerinidae"Parotosuchus" madagascarensis
Les Lydekkerinidae (lydekkerinidés en français) forment une famille éteinte d’amphibiens temnospondyles qui vivaient durant la période du Trias.
Pendant le Trias, les lydekkerinidés ont eu une distribution globale. Ils étaient de petite taille avec des têtes en forme de coin, à peu près triangulaires. Des fossiles ont été trouvés en Russie, au Groenland, en Inde, en Afrique du Sud, à Madagascar et en Australie. Le genre type est Lydekkerina, l'homonyme de la famille est le lydekkerinidé le plus connu.
Selon Paleobiology Database (26 avril 2021)[1] :
Les Lydekkerinidae (lydekkerinidés en français) forment une famille éteinte d’amphibiens temnospondyles qui vivaient durant la période du Trias.
Pendant le Trias, les lydekkerinidés ont eu une distribution globale. Ils étaient de petite taille avec des têtes en forme de coin, à peu près triangulaires. Des fossiles ont été trouvés en Russie, au Groenland, en Inde, en Afrique du Sud, à Madagascar et en Australie. Le genre type est Lydekkerina, l'homonyme de la famille est le lydekkerinidé le plus connu.
I lydekkerinidi (Lydekkerinidae) sono una famiglia di anfibi estinti, appartenenti ai temnospondili. Vissero esclusivamente nel Triassico inferiore (250-245 milioni di anni fa), ma i loro resti sono stati rinvenuti in varie parti del mondo: Sudafrica, Antartide, Groenlandia, India, Russia, Australia e Tasmania.
Il corpo di questi animali era piuttosto allungato e robusto, con zampe corte poste ai lati del corpo. Come per molti temnospondili, il cranio era allungato e appiattito, simile a quello dei coccodrilli; rispetto ai loro antenati del Permiano, i lydekkerinidi possedevano caratteristiche più evolute. Lo sviluppo di questa famiglia ha avuto luogo all'inizio del Triassico inferiore; le prime forme erano piuttosto simili agli esemplari giovanili dei rinesuchidi. Tra i generi più noti di lydekkerinidi, da ricordare Eolydekkerina e Lydekkerina del Sudafrica, Cryobatrachus dell'Antartide e Chomatobatrachus dell'Australia. Le forme più piccole, con caratteristiche giovanili anche allo stadio adulto (pedomorfosi) provengono da zone dove predominavano animali terrestri, mentre le specie più grandi provengono da terreni in cui sono stati rinvenuti resti di anfibi.
I lydekkerinidi (Lydekkerinidae) sono una famiglia di anfibi estinti, appartenenti ai temnospondili. Vissero esclusivamente nel Triassico inferiore (250-245 milioni di anni fa), ma i loro resti sono stati rinvenuti in varie parti del mondo: Sudafrica, Antartide, Groenlandia, India, Russia, Australia e Tasmania.
