Hornerstown Formation
Encyclopedia
The Hornerstown Formation is a Paleogene
or latest Mesozoic
geologic formation. The age of these deposits have been controversial. While most fossils are of animals types known from the earliest Cenozoic
era, several fossils of otherwise exclusively Cretaceous
age have been found. These include remains of the shark Squalicorax
, the teleost fish Enchodus
, several species of ammonite
, and marine lizards referred to the genus Mosasaurus
. Some of these remains show signs of severe abrasion and erosion, however, implying that they are probably re-worked from older deposits. Most of these fossils are restricted to the lowest point in the formation, one rich in fossils and known as the Main Fossiliferous Layer, or MFL. Other explanations for the out-of-place fossils in the MFL is that they represent a time-averaged assemblage that built up and remained unburied during a time of low sediment deposition, or that they were stirred up from deeper in the sediment and deposited together during a tsunami
.
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
or latest Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
geologic formation. The age of these deposits have been controversial. While most fossils are of animals types known from the earliest Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
era, several fossils of otherwise exclusively Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
age have been found. These include remains of the shark Squalicorax
Squalicorax
Squalicorax is a genus of extinct lamniform shark known to have lived during the Cretaceous period. A fully articulated 1.9 m long fossil skeleton of Squalicorax has been found in Kansas, evidence of its presence in the Western Interior Seaway...
, the teleost fish Enchodus
Enchodus
Enchodus is an extinct genus of bony fish. It flourished during the Upper Cretaceous and was small to medium in size. One of the genus' most notable attributes are the large "fangs" at the front of the upper and lower jaws and on the palatine bones, leading to its misleading nickname among fossil...
, several species of ammonite
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
, and marine lizards referred to the genus Mosasaurus
Mosasaurus
Mosasaurus is a genus of mosasaur, carnivorous, aquatic lizards, somewhat resembling flippered crocodiles, with elongated heavy jaws. The genus existed during the Maastrichtian age of the Cretaceous period , around 70-65 millions years ago in the area of modern Western Europe and North America...
. Some of these remains show signs of severe abrasion and erosion, however, implying that they are probably re-worked from older deposits. Most of these fossils are restricted to the lowest point in the formation, one rich in fossils and known as the Main Fossiliferous Layer, or MFL. Other explanations for the out-of-place fossils in the MFL is that they represent a time-averaged assemblage that built up and remained unburied during a time of low sediment deposition, or that they were stirred up from deeper in the sediment and deposited together during a tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
.
Birds
| Bird Bird Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from... s of the Hornerstown Formation |
||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | |
Anatalavis Anatalavis Anatalavis is genus of prehistoric birds related to ducks and geese, perhaps in particular the Magpie-goose. The species Anatalavis rex - formerly placed in Telmatornis - is known from the Hornerstown Formation of New Jersey... |
A. rex. |
|||||
Graculavus Graculavus Graculavus is a prehistoric bird genus that was described by O. C. Marsh. Its remains were found in the Late Cretaceous Austin Chalk of Texas and Lance Formation , and the controversial Hornerstown Formation which straddles the Cretaceous–Paleocene boundary, possibly dating to the Danian stage... |
G. velox |
|||||
Laornis Laornis Laornis is a genus of a prehistoric neornithine birds, known only from Specimen YPM 820, a single tibiotarsus leg bone discovered in the late 19th century. Consequently the genus is monotypic, containing only the species Laornis edvardsianus. Regarding its scientific name, Laornis means "stone... |
L. edwardsianus |
|||||
Palaeotringa Palaeotringa Palaeotringa is a prehistoric bird genus that was discovered by O. C. Marsh during the bone wars. Its remains were found in the controversial Hornerstown Formation of New Jersey which straddles the Cretaceous-Paleocene boundary some 66 million years ago... |
P. littoralis |
|||||
P. vagans |
||||||
Telmatornis Telmatornis Telmatornis is a prehistoric bird genus of unclear affiliations. It apparently lived in the Late Cretaceous; its remains were found in the early Maastrichtian Navesink Formation of New Jersey. A single species is included today, Telmatornis priscus... |
T. priscus |
|||||
Tytthostonyx Tytthostonyx Tytthostonyx is a genus of prehistoric seabird. Found in the much-debated Hornerstown Formation which straddles the Cretaceous-Paleogene boundary 65 million years ago, this animal was apparently closely related to the ancestor of some modern birds, such as Procellariiformes and/or "Pelecaniformes"... |
T. glauconiticus |
|||||