16-845: The Waitemata Group is an Early Miocene geologic group that is exposed in and around the Auckland Region of New Zealand, between the Whangarei Harbour in the North and the Raglan Harbour in the South. The Group is predominantly composed of deep water sandstone and mudstone ( flysch ). The sandstone dominated units form the cliffs around the Waitemata Harbour and rare more resistant conglomerates underlie some of Auckland's prominent ridges. The Waitemata Group
32-652: A bathyal submarine fan . The Meremere Subgroup is finer grained and represents a bathyal submarine fan and basin floor facies . The Waitemata Group is overlain by the volcanic and volcaniclastic Waitakere Group. The Group was once thought to extend from the Oligocene to the Early Miocene, however it is now confined exclusively to the Early Miocene. In the shallow water Kawau Subgroup at least 84 taxa have been identified, half of which were molluscs , however, corals and brachiopods were also found. The environment
48-449: A species of Amphicyon . Fossils of juvenile Agnotherium , Ischyrocyon , and Magericyon all show an unusual type of tooth eruption in which there is a vulnerable stage at about two or three years of age where the subadult animal has no functional molar or carnassial teeth, the only functional cheek teeth being several milk premolars. This period was suggested to be "presumably short" but would have made it very difficult for
64-483: Is recommended that building should be avoided near them. Landslides are commonly caused by bedding plan failure in weathered Waitemata Group sedimentary rock. This is particularly the case when bedding dips towards the prominent coastal cliffs formed by the group's sandstones. Early Miocene The Early Miocene (also known as Lower Miocene ) is a sub-epoch of the Miocene Epoch made up of two stages :
80-515: The Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was preceded by the Oligocene epoch. As the climate started to get cooler, the landscape started to change. New mammals evolved to replace the extinct animals of the Oligocene epoch. The first members of the hyena and weasel family started to evolve to replace
96-589: The Miocene epoch, but recent research suggests a possible North American origin from the miacids Miacis cognitus and M. australis (now renamed as the genera Gustafsonia and Angelarctocyon , respectively). As these are of North American origin, but appear to be early amphicyonids, it may be that the Amphicyonidae actually originates in North America. Other New World amphicyonids include
112-410: The bear-dog 's larger brain, sharper teeth and longer legs built for longer chases helped it to overcome its prey. This geochronology article is a stub . You can help Misplaced Pages by expanding it . Bear-dog † Amphicyoninae † Daphoeninae † Haplocyoninae † Temnocyoninae † Thaumastocyoninae Amphicyonidae is an extinct family of terrestrial carnivorans belonging to
128-679: The suborder Caniformia . They first appeared in North America in the middle Eocene (around 45 mya), spread to Europe by the late Eocene (35 mya), and further spread to Asia and Africa by the early Miocene (23 mya). They had largely disappeared worldwide by the late Miocene (5 mya), with the latest recorded species at the end of the Miocene in Africa. They were among the first carnivorans to evolve large body size. Amphicyonids are colloquially referred to as " bear-dogs ". The family
144-519: The Canidae, which are hypercarnivores or mesocarnivores . There is often some confusion with the similar looking (and similarly named) "dog-bears", a more derived group of caniforms that is sometimes classified as a family ( Hemicyonidae ), but is more often considered a primitive subfamily of ursids ( Hemicyoninae ). It has long been uncertain where amphicyonids originated. It was thought that they may have crossed from Europe to North America during
160-760: The early Miocene ( Otaian ) and range in thickness from 10 to 45 m. These basal lithologies are varied and different from the overlying flyish basin. They overly the Te Kuiti Group sediments and the Mesozoic basement. This subgroup includes the Papakura Limestone, Tipakuri Sandstone Formation and the Cape Rodney Formation ( greywacke conglomerate and breccia). The Warkworth Subgroup is up to 1000m of inter-bedded sandstone and mudstone formed from turbidity currents . These accumulated in
176-438: The extinct Hyaenodon , entelodonts and bear-dogs . The chalicotheres survived the Oligocene epoch. A new genus of entelodont called Daeodon evolved in order to adapt to the new habitats and hunt the new prey animals of the Early Miocene epoch; it quickly became the top predator of North America . But it became extinct due to competition from Amphicyon , a newcomer from Eurasia . Amphicyon bested Daeodon because
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#1732783840454192-482: The oldest known amphicyonid, Daphoenus (37–16 Mya). Amphicyonids began to decline in the late Miocene, and disappeared by the end of the epoch. The exact reasons for this are unclear. The most recent known amphicyonid remains are teeth known from the Dhok Pathan horizon, northern Pakistan , dating to 7.4-5.3 mya. The species is classically named Arctamphicyon lydekkeri , which may actually be synonymous with
208-475: The origin of both bears and dogs. Amphicyonids ranged in size from as small as 5 kg (11 lb) and as large as 100 to 773 kg (220 to 1,704 lb) and evolved from wolf-like to bear-like body forms. Early amphicyonids, such as Daphoenodon , possessed a digitigrade posture and locomotion (walking on their toes), while many of the later and larger species were plantigrade or semiplantigrade. The amphicyonids were obligate carnivores , unlike
224-678: Was deposited within fault controlled basins. These were bounded to the North and South by up faulted Mesozoic basement sedimentary rocks and volcanic rocks to the East and West. The sedimentary source for the Group's sandstone is a mix of these basement sediments of the Waipapa Terrane and the mostly intermediate volcanic rocks. The maximum water depth of the Waitemata Group basin was 2,000 m. The basal strata (Kawau Subgroup) are from
240-562: Was erected by Haeckel in 1866 (also attributed to Trouessart 1885). Their exact position has long been disputed. Some early paleontologists defined them as members of the family Canidae , but the modern consensus is that they form their own family. Some researchers have defined it as the sister clade to ursids ( bears ), based on morphological analysis of the ear region. However, cladistic analysis and reclassification of several species of early carnivore as amphicyonids has strongly suggested that they may be basal caniforms, from lineages older than
256-496: Was inferred to be a rocky shore. Nereites trace fossils are common throughout the deeper water sequence. The Waitemata Group formed during the emplacement of the Northland Allochthon and is sometimes inter-bedded with it. The Allochthon continued to move South during deposition and some areas of the Waitemata Group are therefore extensively deformed. The Waitemata Group forms steep rapidly eroding cliffs and it
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