Swift-like Apodiform Birds from the Early Eocene London Clay of Walton-on-the-Naze in Essex, southern England.

The modern Avian Order Apodiformes includes the Swifts, Apodidae, Treeswifts, Hemiprocnidae, and Hummingbirds, Trochilidae. The morphological distinctness of this group of highly specialised fliers has made determining how they are related to other Bird groups difficult, although modern phylogenetic techniques have revealed that they are the sister group to the Owlet-Nightjars, Aegotheliformes. Although a number of fossil Apodiformes are known, with the oldest coming from the Early Eocene London Clay of southern England, the early history of the group is not well understood, as, in common with most Birds, the skeletons of Apodiformes tend to be small and delicate, not lending themselves to preservation, so that most fossils assigned are of isolated, and often fragmentary, bones.

The earliest known members of the group are Primapus lacki, which is known from a nearly-complete humerus from the London Clay at Bognor Regis in West Sussex, and the distal portion of a second humerus from the Isle of Sheppy in Kent, and Eocypselus vincenti, which was described from associated wing and pectoral girdle bones from Walton-on-the-Naze in Essex, with partial skeletons assigned to the same species described from the early Eocene Fur Formation  in Denmark. A second species of Eocypselus, Eocypselus rowei, has been described from the Early Eocene Green River Formation of Wyoming.

The classification of these early Apodiform Birds remains unclear. Primapus lacki has been assigned to the Aegialornithidae, an extinct group which also includes four species from the Middle Eocene-Early Oligocene Quercy fissure fillings of France, and which may be stem group Apodiformes or more closely related to Swifts than other members of the group. Eocypselus vincenti is sometimes considered to be an early member of the Hemiprocnidae, but more usually to an Apodiform stem group, the Eocypselidae.

In a paper published in the journal Ibis on 22 March 2024, Gerald Mayr of the Ornithological Section of the Senckenberg Research Institute and Natural History Museum Frankfurt, and Andrew Kitchener of the Department of Natural Sciences at National Museums Scotland, and the School of Geosciences at the University of Edinburgh, describe multiple new skeletons of Apodiform Birds from the Early Eocene London Clay at Walton-on-the-Naze in Essex, from the collection of the late Michael Daniels, an Edinburgh resident and amateur palaeontologist who passed away in 2021, leaving his collection to National Museums Scotland. From this material they describe three new species of Eocypselus, as well as new specimens of Eocypselus vincenti and Primapus lacki, which add significantly to our understanding of these Birds.

The first new species described is Eocypselus geminus, where 'geminus' means 'twin' in reference to the fact that this species closely resembles Eocypselus vincenti. It is described from a partial disarticulated skeleton, specimen NMS.Z.2021.40.116, which comprises a partial rostrum and mandible, the axis,  a furcula (wishbone) broken into three pieces, the right scapula, the right coracoid in a piece of matrix, a partial sternum, a partial left humerus, the left radius, the proximal portion of the right radius, the right phalanx proximalis  digiti majoris,  both carpometacarpi, fragments of the pelvis, a right tarsometatarsus lacking its proximal end, a few pedal phalanges and the anungual phalanx. A second specimen is also referred to this species, NMS.Z.2021.40.117, which comprises the left coracoid, the omal extremity of the right coracoid, the left humerus, the proximal portion of the right humerus, the left ulna, and the proximal portion of the right ulna. A mediolaterally narrow premaxilla found associated with this specimen belongs to a different, non-Apodiform species.

Eocypselus geminus from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Mayr & Kitchiner (2024).

While Eocypselus geminus resembles Eocypselus vincenti closely, the two species can be distinguished on the basis that the processus procoracoideus of the coracoid projects less strongly towards the processus acrocoracoideus in Eocypselus geminus than in Eocypselus vincenti, the furcula of Eocypselus geminus has wider omal sections of the scapi clavicularum than that of Eocypselus vincenti, and the humerus of Eocypselus geminus, which has a stouter shaft and a dorsoventrally wider distal end than that of Eocypselus vincenti.

The second new species described is named Eocypselus paulomajor, where 'paulomajor' is intended to mean 'somewhat larger' in Latin, in reference to the size of the species, which is larger than Eocypselus vincenti. This species is described from a single specimen, NMS.Z.2021.40.118, which comprises a partial furcula, a left coracoid, and a left ulna.

Eocypselus paulomajor from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Mayr & Kitchiner (2024).

The third new species described is named Eocypselus grandissimus, where 'grandissimus' means 'the largest' in reference to the fact that this specimen is larger than all other members of the genus. It is described from a single specimen, NMS.Z.2021.40.119, which comprises a few vertebrae, both coracoids, both scapulae, the cranial portion of the sternum, the distal end of the right humerus, the proximal end of the left humerus, a partial left carpometacarpus, the distal end of the left femur, and one pedal phalanx. A distal left humerus associated with the specimen belongs to a non-Apodiform species.

Eocypselus grandissimus from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Mayr & Kitchiner (2024).

A number of further specimens are referred to Eocypselus, but not to any particular species. All are of similar size to Eocypselus geminus and Eocypselus vincenti, but cannot be confidently be assigned to either species, and may potentially represent additional, undescribed, species. although without further, more complete, specimens to refer to, it would be impossible to be certain of this.

A new specimen of Primapus lacki is also described. This specimen, NMS.Z.2021.40.133, comprises the furcula, the right coracoid, the left and right humeri lacking distal ends, the left radius, a partial right carpometacarpus, and a single pedal phalanx.

Primapus lacki from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Mayr & Kitchiner (2024).

Mayr and Kitchiner consider the Aegialornithidae and Eocypselidae to be stem-group Apodiform Birds, forming sister taxa to the crown group Apodiformes. Primapus lacki represents the earliest representative of the Aegialornithidae, a group which persisted at least 19 million years, into the Early Oligocene. In contrast, the Eocypselidae are known only from Early Eocene deposits, and appear to have been a short-lived group. The crown group Apodiformes are unknown in the Early Eocene, with the earliest known example being Scaniacypselus szarskii, thought to be an early Swift, from the Middle Eocene Messel Shale of Germany. 

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Residents evacuated from their homes after landslide on the Isle of Sheppey.

Around 20 households have been evacuated following a landslide on the north coast of the Isle of Sheppey, on the north coast of Kent in southeast England, on Monday 1 June 2020. The event, a slump on an exposure of London Clay in the cliffs, is about fifteen metres wide and about two metres deep, and partially undermined one house, with the clear potential to extend further, leading the Kent Fire and Rescue Service to order the evacuation of twenty homes, with a further thirteen warned that they could be asked to leave if the slip spread further.

Aerial view of a landslide that partially undermined a house on the north coast of the Isle of Sheppey on Monday 1 June 2020. Kent Fire and Rescue Service.

Photographs of the landslide show excessive water pooled within the slumped material, this is fairly typical of landslides, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. However, the north Kent coastal area has been suffering a prolonged bout of dry weather, making such an explanation for the event unlikely. Reports in the local press state that cracks were first seen on the cliffs on Friday 29 May, probably a result of dry cracking of the clay, and that locals had responded by pouring water onto the affected area in the hope of improving the cliffs cohesion, something which had reportedly worked in the past, but which seems highly likely to have triggered the landslip.

Wider angle view of the 1 June 2020 Sheppey landslip. SWNS.

The north coast of the Isle of Sheppey is popular with fossil collectors due to the large number of Eocene fossils it produces. The London Clay outcrops directly on the coast here, and as this is a poorly consolidated, soft sediment, it is easily eroded by the action of the sea, revealing large numbers of highly fossiliferous phosphate nodules, noted for the high quality plant macrofossils (particularly Mangrove Plants) and marine invertebrates (particularly articulated Decapod Crustaceans) that they produce. Unfortunately the same sediment makes conditions at the site extremely treacherous, as the clay readily absorbs large volumes of water, turning into a highly sticky mud that can cause cliff failures in the area, exposing new fossil material, but which can also  trap the unwary, as the weight of a human footfall is sufficient to squeeze the water out of the mud beneath the foot, creating a vacuum that prevents the foot from being lifted again.

A fossil Shark's tooth from the London Clay on the north coast of the Isle of Sheppey. UK Fossils.

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Two teenaged girls rescued from soft mud at popular English fossil hunting site.

Two teenaged girls were rescues by teams from Kent Fire and Rescue and the Whitstable RNLI after becoming trapped in soft mud at Warden Point on the Isle of Sheppey (off the north coast of Kent in the Thames Estuary) on Saturday 2014. Initial attempts to by the Fire Service to reach the girls from land were hampered by the incoming tide, leading to a crew from the Lifeboat Institution to be called. The girls were reported to be suffering from mild hypothermia when rescued, but otherwise unhurt.

The two girls trapped in soft mud at warden point on 13 December 2014. Whitstable RNLI.

Warden Point is popular with fossil collectors due to the large number of Eocene fossils it produces. The London Clay outcrops directly on the coast here, and as this is a poorly consolidated, soft sediment, it is easily eroded by the action of the sea, revealing large numbers of highly fossiliferous phosphate nodules, noted for the high quality plant macrofossils (particularly Mangrove Plants) and marine invertebrates (particularly articulated Decapod Crustaceans) that they produce. Unfortunately the same sediment makes conditions at the site extremely treacherous, as the clay readily absorbs large volumes of water, turning into a highly sticky mud that an trap the unwary, as the weight of a human footfall is sufficient to squeeze the water out of the mud beneath the foot, creating a vacuum that prevents the foot from being lifted again.

An articulated Eocene Lobster, Hoploparia sp., from a phosphate nodule collected at Warden Point on the Isle of Sheppey. Discovering Fossils.

Weather conditions across much of the UK have been extremely wet for the past few days, driven by a storm system the popular press have dubbed the ‘Weather Bomb’, driven by warm weather over the Atlantic Ocean, which has brought with it an area of very low pressure, leading to a storm surge that has brought high tides to coastal areas, and very high rainfall levels. The low pressure above oceanic storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall.

The two girls trapped in soft mud at warden point on 13 December 2014. Whitstable RNLI.

his can cause additional flooding on land, as well as landslides, which are are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. The extent to which this has happened at Warden Point this weekend is unclear, but photographs from the Whitstable RNLI appear to show signs of recent slumping, and the mud produced by recent slumps is particularly dangerous.

Satellite image showing the typical extent of slumping on the foreshore at Warden Point. Google Maps.

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Rockfall at Penarth Cliffs.

A large section of cliff at Penarth in the Vale of Glamorgan, roughly 8.4 km southwest of Cardiff, has collapsed onto the foreshore. The incident happened at about 12.40 pm British Summertime (about 11.40 am...

German man receives third degree burns after trousers set on fire by 'amber' pebble.

A 67-year-old German Man is being treated for third degree burns after a pebble he picked up while collecting amber on a beach on the country's Baltic...

Section of White Cliffs of Dover collapses into the sea.

On Friday 9 March 2012 a large part of the White Cliffs of Dover, in the Crab Bay area, between Langdon Cliffs and the South Foreland Lighthouse fell into the sea. This is thought to be a result of water soaking into the porous chalk, then freezing, cracking the rock of the...

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