# Anatomy and relationships of †Aipichthys pretiosus and †‘Aipichthys’ nuchalis (Acanthomorpha: Lampridomorpha), with a review of Late Cretaceous relatives of oarfishes and their allies

Daniel Delbarre, Donald Davesne, Matt Friedman

► To cite this version:

Daniel Delbarre, Donald Davesne, Matt Friedman. Anatomy and relationships of †Aipichthys pretiosus and †‘Aipichthys’ nuchalis (Acanthomorpha: Lampridomorpha), with a review of Late Cretaceous relatives of oarfishes and their allies. Journal of Systematic Palaeontology, 2015, 14 (7), pp.545-567. 10.1080/14772019.2015.1078538. hal-05375285

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# Anatomy and relationships of †*Aipichthys pretiosus* and †‘*Aipichthys nuchalis* (Acanthomorpha: Lampridomorpha), with a review of Late Cretaceous relatives of oarfishes and their allies

Daniel J. Delbarre<fnref n="1" />*, Donald Davesne<fnref n="2" />,<fnref n="3" /> and Matt Friedman<fnref n="1" />

<footnote n="1">¹Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK</footnote>

<footnote n="2">²Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207 CNRS-MNHN-UPMC, Muséum national d'Histoire naturelle, Sorbonne Universités, CP 38, 57 rue Cuvier, 75005, Paris, France</footnote>

<footnote n="3">³Institut de Systématique, Évolution, Biodiversité, UMR 7205 CNRS-MNHN-UPMC-EPHE, Muséum national d'Histoire naturelle, Sorbonne Universités, CP 26, 57 rue Cuvier, 75005, Paris, France</footnote>

<footnote>*Corresponding author. Email: daniel.delbarre@earth.ox.ac.uk; Telephone: +44 01865 272073</footnote>
**Abstract**

The Cenomanian acanthomorph teleost †*Aipichthys* is best known from two species: †*Aipichthys minor* and †*Aipichthys velifer*. Two poorly studied species of †*Aipichthys*, †*Aipichthys pretiosus* from Slovenia and †*Aipichthys nuchalis* from the English Chalk, have been excluded from all recent studies of the genus. Previous accounts of †*A. pretiosus* – the type species of †*Aipichthys* – are inadequate, while †*A. nuchalis* has been described as too incomplete to interpret. Here we completely redescribe †*A. pretiosus* and utilize computed tomography to reveal previously hidden skeletal anatomy of †*A. nuchalis*. †*A. pretiosus* has a long sagittal crest, with the supraoccipital, frontal and mesethmoid bones contributing to this structure. Based on this and other features, we find that †*A. pretiosus* belongs to a clade that is more closely related to extant Lampridiformes than all other nominal species of †*Aipichthys*. As †*A. pretiosus* is the type species for the genus, we recommend all other species of the genus should be temporarily referred to as †‘*Aipichthys*’. †‘*A.*’ *nuchalis* possesses a concave posterior margin and a thickened anterior margin to the supraoccipital crest, and is placed in a polytomy alongside †‘*A.*’ *minor*, †‘*A.*’ *velifer*, †‘*Aipichthys*’ *oblongus* and †*Freigichthys*. Further investigation is needed to determine whether †‘*Aipichthys*’ is congeneric with, and can be reassigned to †*Freigichthys* or whether a new generic name is needed for these taxa.

We also include two additional taxa in our analysis: †*Nardovelifer altipinnis*, the oldest
fossil previously attributed to the lampridiform crown, and †*Gigapteryx tethyestris*, an *incertae
sedis* acanthopterygian. We find that †*Nardovelifer* has a number of primitive characters not
found in crown Lampridiformes, and resolve it as a stem lampridiform. We find that †*Gigapteryx*
is closely related to †*Pycnosteroides*, which collectively are the sister taxa to all other
lampridomorphs. Finally, we examine the diversity of Cretaceous lampridomorphs and discuss
their palaeobiogeography and palaeoecology.

**Keywords:** †*Aipichthys*, Lampridomorpha, Lampridiformes, Acanthomorpha, Cretaceous
**Introduction**

†*Aipichthys* is a one of the oldest-known members of Acanthomorpha (spiny-rayed fishes), a group that comprises one third of modern vertebrate species (Stiassny *et al.* 2004). †*Aipichthys* contains five Cenomanian species: the type species †*Aipichthys pretiosus* Steindachner, 1860, plus †*Aipichthys minor* (Pictet, 1850), †*Aipichthys velifer* Woodward, 1901, †*Aipichthys nuchalis* (Dixon, 1850) and †*Aipichthys oblongus* Gayet, 1980a. Most species of †*Aipichthys* derive from the Lebanese Lagerstätten of Hakel and Hadjoula, and it is these examples that provide the most detailed picture of anatomy in the genus (e.g. Gayet 1980a; Otero & Gayet 1996). †*Aipichthys pretiosus* and †*A. nuchalis* are not known from Lebanese deposits, and are only found in Cenomanian deposits from Komen, Slovenia and the English Chalk of the United Kingdom, respectively.

The affinities of †*Aipichthys* to both fossil and extant acanthomorphs has undergone substantial revision since the genus was established. Early interpretations placed †*Aipichthys* in the percomorph families Ephippidae (spadefishes; Dixon 1850), Carangidae (jacks; Woodward 1887; Gregory 1933) and Scorpidae (Kyphosidae of modern usage) (sea chubs; Boulenger 1904). By contrast, more recent interpretations view †*Aipichthys* and remaining †‘Aipichthyidae’ (†*Paraipichthys lusitanicus* Gaudant, 1978, and †*Freigichthys elleipsis* Otero, 1997) as related to deeply diverging branches of Acanthomorpha: Beryciformes (Regan 1911), Paracanthopterygii (Gayet 1980a) and Lampridiformes (Patterson 1964, 1968, 1993; Rosen & Patterson 1969; Oelschläger 1983). The first phylogenetic analyses to include †‘Aipichthyidae’ united them with another fossil family, †‘Aipichthyoididae’, to form the superfamily †‘Aipichthyoidea’ (Otero & Gayet 1995, 1996). This in turn was placed as the sister group of Euacanthomorpha, a result echoed by a further analysis using the same dataset (Alvarado-Ortega & Than-Marchese 2012). None of these studies included Lampridiformes (oarfish and allies), a major early-diverging lineage of acanthomorphs (Olney *et al.* 1993; Johnson & Patterson 1993). Davesne *et al.* (2014) recently re-evaluated the affinities of †‘aipichthyoids’ using a wider sample of living lineages, and found that they represent a grade of stem lampridiforms.

Species of †*Aipichthys* are known in varying detail. †*A. velifer*, †*A. minor* and, to a lesser degree, †*A. oblongus*, have been well described (e.g. Patterson 1964; Gayet 1980a) and are represented in all phylogenetic analyses incorporating †‘aipichthyoids’. However the two remaining species of †*Aipichthys*, †*A. pretiosus* and †*A. nuchalis*, have not been included in any of these studies. The principal goals of this paper are to review the anatomy of these species from Slovenia and England, and to determine their phylogenetic placement relative to other species of †*Aipichthys* and among †‘aipichthyoids’ more generally. Restudy of each of these poorly known examples of †*Aipichthys* has potential to provide additional insights. First, †*A. pretiosus* is the type species of †*Aipichthys*, and thus is important for assessing the attribution of other species to the genus. Second, †*A. nuchalis* is one of the few non-Tethyan †‘aipichthyoids’ known, and the only example preserved in three dimensions rather than as a compression fossil.

As a consequence of the meagre anatomical details available in published accounts (Woodward 1887; Gorjanovic-Kramberger 1895), †*A. pretiosus* and †*A. nuchalis* have been excluded from previous phylogenetic analyses. Consequently, their affinity to other nominal species of †*Aipichthys* is assumed but has not been formally tested. Based on our re-examination of †*A. pretiosus* (using conventional methods) and †*A. nuchalis* (using high-resolution micro computed tomography [µCT] scanning), we provide new descriptions of these enigmatic species, and investigate their relationships to one another, to other nominal species of †*Aipichthys*, and among Lampridomorpha (sensu Davesne *et al.* 2014) more generally.
# Materials and methods

## Institutional abbreviations

EY, The Hebrew University of Jerusalem, Jerusalem, Israel; FSL, Faculté des Sciences de Lyon, Lyon, France; IHNFG, Instituto de Historia Natural y Ecología, Tuxtla Gutiérrez, Chiapas, Mexico; IST, Instituto Superior Técnico, Lisbon, Portugal; MNHN, Muséum national d'Histoire naturelle, Paris, France; MSNV, Museo Civico di Storia Naturale di Verona, Verona, Italy; NHMUK, Natural History Museum, London, United Kingdom; NHMW, Naturhistorisches Museum, Vienna, Austria.

## Anatomical abbreviations

AfPt, anal-fin pterygiophore; AfR, anal-fin ray; AfSp, anal-fin spine; Ang, anguloarticular; Bas, basisphenoid; Bra, branchial arch; Brs, branchiostegals; Cer, ceratohyal; Cle, cleithrum; Cor, coracoid; Den, dentary; DfPt, dorsal-fin pterygiophore; DfR, dorsal-fin ray; DfSp, dorsal-fin spine; Ect, ectopterygoid; End, endopterygoid; Epi, epiotic; Epn, epineural; Epp, epipleural; Epu, epural; Fr, frontal; Hmax, hemaxanal complex; Hs, haemal spine; HsPu, haemal spine of preural centrum; Hym, hyomandibula; Hyp, hypural; Inf, infraorbital; Iop, interopercle; IW, internal wings of pelvic bones; Lac, lacrimal; LEth, lateral ethmoid; Max, maxilla; Mes, mesethmoid; Met, metapterygoid; MP, median process of pelvic bones; Nas, nasal; Ns, neural spine; NsPu, neural spine of preural centrum; Obs, orbitosphenoid; Op, opercle; Pal, palatine; Par, parietal; PclD, dorsal postcleithrum; PclV, ventral postcleithrum; Pel, pelvic bone; PfR, pectoral-fin ray; PfRd, pectoral-fin radials; Phy, parhypural; PMx, premaxilla; Pop, preopercle; PP, posterior process of pelvic bones; Psp, parasphenoid; PsUr, pseudourostylar complex; Pt, posttemporal; Pto, pterotic; Qu, quadrate; Ret, retroarticular; Sca, scapula; Scl, supracleithrum; Smx, supramaxilla; Soc, supraoccipital; Spn, supraneural; Uro, uroneural; V, vertebral centrum; VRS, ventral ridge scale. Numbers may follow some abbreviations, when there is more than one structure (e.g. Hyp1 and Hyp2, to represent hypurals one and two respectively). Structures from the left and right sides are identified with (l) and (r), respectively.

## Dagger symbol

The dagger symbol (†) is used to identify extinct taxa (cf. Patterson & Rosen 1977).

## Computed tomography scanning

†*Aipichthys nuchalis* was scanned at the Natural History Museum, London, United Kingdom using a Metris X-Tek HMX ST 225 CT scanner. The CT scan was segmented using the commercial biomedical software Mimics (version 15.01) produced by Materialise. Local thresholds of grey values were used to create masks that differentiate between the fossil and the surrounding matrix. Individual masks were then combined to produce a model of the whole specimen. For a more in-depth explanation of processing CT scans of fossil material, see Abel *et al.* (2012). Blender (Blender Foundation, 2013) version 2.69 was used to light the models and produce renderings for the figures.

## Phylogenetic analysis

We analysed the phylogenetic placements of †*Aipichthys pretiosus* and †*A. nuchalis* by including these species in the character-by-taxon matrix of Davesne *et al.* (2014), which itself is largely based on matrices presented earlier by Otero & Gayet (1995, 1996) and Alvarado-Ortega & Than-Marchese (2012). We also included seven new characters (Table S1) and two other taxa: the earliest putative crown lampridiform †*Nardovelifer altipinnis* Sorbini & Sorbini, 1999, from the Late Cretaceous (Campanian–Maastrichtian) of Italy and †*Gigapteryx tethyestris* Forey *et al.*,
2003, an *incertae sedis* acanthopterygian. Contrary to Davesne *et al.* (2014), we did not include †*Paraipichthys lusitanicus* in the analysis because of the dubious status of the paratype specimen (see Discussion). Character states were coded using Nexus Data Editor version 0.5 (Page 2001) and then analysed using PAUP* version 4.0b10 (Swofford 2003). The branch-and-bound algorithm was used to search for the most parsimonious trees, from which a strict consensus tree was derived. PAUP* was subsequently used to calculate the consistency index, homoplasy index, retention index and the rescaled consistency index. A bootstrap analysis was subsequently run with PAUP* with a 'heuristic' search option and 1000 replicates to calculate support values for each node. The Bremer indexes were estimated automatically using a PAUP* script generated by TreeRot 2 (Sorenson 1999).

## Standard length estimation and body depth index

The type and only specimen of †*A. nuchalis* is incomplete posteriorly. We therefore derived an estimated standard length using the following procedure: We measured †*A. nuchalis* as well as †*Aipichthys minor* and †*Aipichthys velifer* from the most anterior point to the posterior end of the 11th caudal vertebrae (the most posterior part of †*A. nuchalis*) (measurement A). The standard length (measurement B) of †*A. minor* and †*A. velifer* was also recorded. For †*A. minor* and †*A. velifer*, measurement B was then divided by measurement A to produce a ratio. This was repeated on a number of specimens of †*A. minor* and †*A. velifer*. The smallest and largest ratios were then multiplied with measurement A of †*A. nuchalis* to give an estimated size range. †*A. minor* and †*A. velifer* were used in this calculation as they represent taxa with different numbers of vertebrae, and are both known from a number of specimens. †*Aipichthys oblongus* and †*Freigichthys* were not used as †*A. oblongus* is only known from one disarticulated specimen, and †*Freigichthys* is only known from one articulated specimen.

The body depth index was calculated by dividing the height of the hemaxanal complex by measurement A.

## Systematic palaeontology

Infraclass **Teleostei** Müller, 1846

Subcohort **Neoteleostei** Nelson, 1969

Infracohort **Eurypterygii** Rosen, 1973

Section **Ctenosquamata** Rosen, 1973

Subsection **Acanthomorpha** Rosen, 1973

Superorder **Lampridomorpha** sensu Davesne *et al.* (2014)

Genus †*Aipichthys* Steindachner, 1860

†*Aipichthys pretiosus* Steindachner, 1860

(Figs 1–3)

1860 †*Aipichtys pretiosus* Steindachner: 763, pl. 1, fig. 1.

1882 †*Aipichthys pretiosus* Steindachner; Bassani: 262.

1895 †*Aipichthys pretiosus* Steindachner; Gorjanovic-Kramberger: 46, pl. 2, fig. 3.

1901 †*Aipichthys pretiosus* Steindachner; Woodward: 427.

1946 †*Aipichthys pretiosus* Steindachner; d'Erasmo: 113, fig. 30.

1964 †*Aipichthys pretiosus* Steindachner; Patterson: 393.

**Diagnosis.** Lampridomorph similar only to †*Aspesaipichthys* Taverne, 2004 and †*Aipichthyoides* Gayet, 1980b with supraoccipital, frontal and mesethmoid contributing to a long sagittal crest.
The anterior edge of the crest is not thickened, and unlike the condition seen in †'Aipichthys', †Freigichthys and †Gigapteryx. Differs from all Cretaceous lampridomorphs, except some specimens of †Errachidia pentaspinosa Murray & Wilson, 2014, in possessing 12 abdominal and 14 caudal vertebrae. The first three haemal spines are closely associated with each other. This condition is not seen in other Cretaceous lampridomorphs. Similar to †'Aipichthyoididae' and Lampridiformes in having the lower hypurals fused together. Retains six hypurals, unlike †Aspesaipichthys and †Aipichthyoides where there has been a reduction to five.

**Material.** Holotype NHMW 1857. XXXVIII. 7., an articulated specimen preserved in left-lateral view. One other specimen from an unrecorded locality in Lesina has been reported (Gorjanovic-Kramberger 1892, 1895). The location of this fossil has not been mentioned since 1895, and its present whereabouts are unknown.

**Occurrence.** Volčji Grad, Komen, Slovenia. Komen Limestone (Steindachner 1860; Bassani 1882; Cavin *et al.* 2000). This horizon is dated to the Cenomanian based on the presence of the mollusc †Chondrodonta spp. and the foraminiferan †Broeckina (Pastrikella) balcanica (Cavin *et al.* 2000).

**Notes.** The status of †A. pretiosus as the type species for †Aipichthys is unambiguous as Steindachner (1860) was the first to use the generic name †Aipichthys when he described †A. pretiosus. Although †'Aipichthys' minor and †'Aipichthys' nuchalis were described before †A. pretiosus by Pictet (1850) and Dixon (1850) respectively, they were only assigned to †Aipichthys by Woodward (1901). When first described by Steindachner (1860) the genus was originally named †Aipichtys, although the alternative spelling, †Aipichthys, has since been used almost exclusively (e.g. Bassani 1882; Gorjanovich-Kramberger 1895; Woodward 1901, 1902; Patterson 1964). †Aipichthys has become the recognized spelling though prevailing usage, although some of the older literature uses the original spelling (e.g. Steindachner 1860; Hay 1903).

**Description**

**Measurements and meristics.** Standard length of 47 mm and 60 mm total length. There are 26 vertebrae present: 12 abdominal and 14 caudal. Fin formulae are as follows: dorsal, III + 22?; anal, III + 17?; caudal, 6+I+9/8+I+5; pectoral, 12-14?; pelvic, ? The predorsal formula is: 0+0+0/x+x/.

**Skull.** The head is approximately two and a half times tall as it is long, although the neurocranium is of equal height and length (Figs 1-2). The substantial sagittal crest is nearly as large as the remainder of the skull. Although the skull is articulated, poor surface detail of component ossifications make detailed interpretation difficult. Bones that can be identified include: frontal, supraoccipital, parietal, epiotic, pterotic, orbitosphenoid, basisphenoid, parasphenoid, mesethmoid and lateral ethmoid.

The frontal forms the roof of the skull and defines the dorsal margin of the orbit. No canals or pores are apparent, but this likely reflects poor preservation. The conspicuous sagittal crest of the skull is composed of three bones: supraoccipital, frontal and mesethmoid. A number of ridges ornament the crest, and are aligned perpendicular to its anterodorsal border. The posterior part of the crest is composed of the supraoccipital, which makes the largest contribution of the three constituent bones. The supraoccipital projects posterodorsally to the level of the first supraneural. The posterior region of the supraoccipital is incomplete, and it is unclear whether its hind margin would have been convex or concave. Anteriorly, the supraoccipital contacts the smaller frontal, which forms the middle part of the crest. The frontal in turn joins the mesethmoid, the most anterior and smallest part of the crest.

Both the parietal and epiotic are poorly preserved. No surface features can be discerned on the unremarkable parietal. The posterior margin, where the parietal meets the epiotic, cannot
be detected. The epiotic bears a groove marking the point of articulation with the dorsal arm of
the posttemporal.

The dorsal surface of the pterotic bears a large open groove for the frontal branch of the
sensory canal. There is a lateral opening for the preopercular branch, although it is unclear
whether this would have taken the form of a pore or open indentation (sensu Otero & Gayet
1996, pp. 320–321, fig. 6) in life due to poor preservation.

The orbitosphenoid lies in the posterodorsal corner of the orbit. The basisphenoid forms an elongated strut between the posterior margin of the orbit and the parasphenoid. The anterior surface of the bone is straight, but its posterior margin is concave. The parasphenoid is elongated with a gentle ventral curve. The anterior apex of the parasphenoid is obscured by the overlying lacrimal and mesethmoid. The ascending process of the parasphenoid forms the posterior margin of the orbit.

As well as forming part of the sagittal crest, the mesethmoid forms the most anterior part of the skull, inserting medially below the frontals. It is unclear where this ventral component of the mesethmoid ends and the more posteriorly positioned lateral ethmoid starts. The posterior border of the lateral ethmoid is easily discerned, although the most ventral part appears to be missing as it does not overlie the parasphenoid or articulate with the lacrimal.

**Jaws.** Preserved elements of the upper jaw include the left premaxilla, maxilla and one supramaxilla (Figs 1–2). These bones have been rotated anteroventrally, and are not in a natural position relative to the rest of the skull. The premaxilla has an elongated alveolar process, similar in length to the maxilla, and has small teeth along its oral margin. The ascending and articular processes are distinct. The dorsal extent of these processes is not preserved. The full length of the maxilla is preserved dorsal to the premaxilla. It has a process at its anterior end for articulation with the premaxilla. The supramaxilla is approximately half the length of the maxilla. It is not clear whether a second smaller supramaxilla may have also been present.

The lower jaw is complete and remains in life position (Figs 1–2). The posterior border of the dentary is 'V'-shaped, where it articulates with the anguloarticular. The small retroarticular is positioned to the posterior end of the anguloarticular. The dorsal margin of the dentary is thickened and bears a band of teeth along its oral margin. Three pores are visible near the ventral margin of the dentary, and mark the position of the sensory canal. There is a modest coronoid process.

**Infraorbital series.** The lacrimal is the only ossification of the infraorbital series that can be clearly discerned (Figs 1–2). Only the anterior and ventral margins of the lacrimal are intact, but it appears that the complete bone would have been ovoid with a long vertical axis. It is not possible to determine whether there would have been a dorsal process. The lateral surface of the lacrimal is ornamented with at least six thick, parallel ridges that correspond with branches of the underlying sensory canals. The remaining infraorbitals can only be detected as a length of bone, with divisions between individual ossifications unclear.

**Suspensorium.** Preserved elements of the suspensorium include the hyomandibula, metapterygoid, quadrate, ectopterygoid and palatine (Figs 1–2). No symplectic or endopterygoid are visible. The body of the hyomandibula is narrow, and bears a single articular facet at its dorsal terminus. The hyomandibula bears a large anterior process, which, although not complete, projects to approximately mid-orbit. No posterior process can be seen. The poorly preserved metapterygoid lies anterior to the ventral shaft of the hyomandibula. The quadrate is a large triangular bone, widest dorsally and tapering into an articular condyle ventrally. The
ectopterygoid is positioned to the anterior margin of the quadrate and the ventral margin of the palatine. The posterior part of the palatine is expanded dorsally into a semi-circular plate. The anterior end of the palatine is obscured by the overlying lacrimal.

**Opercular series.** The preoperculum, operculum and a small part of the interoperculum are preserved (Figs 1–2). The preoperculum is more complete ventrally, with much of its dorsal limb missing. The preoperculum is elongated along the dorsal-ventral axis, curving anteriorly at the ventral terminus. No pores are visible, but there is a well-developed groove for the sensory canal. The operculum appears to be from the right side and is presented in medial view. This bone is generally smooth, although there is a low, vertical ridge.

**Ventral hyoid arch and gill skeleton.** There are four, or possibly five, branchiostegals preserved in articulation with what is most likely the anterior ceratohyal (Figs 1–2). The anterior ceratohyal is only well preserved along its ventral margin. Thus it is not possible to comment on whether any foramen or groove is present. The branchiostegals are gently curved and appear relatively short. However, it seems likely that they are incompletely preserved distally.

The branchial arches can be seen in two places: anteroventral to the metapterygoid and hyomandibula, and where part of the dorsal limb of the preoperculum is missing (Figs 1–2). However, no significant features are apparent in these fragmentary remains.

**Axial skeleton.** The vertebral column is complete and consists of 12 abdominal and 14 caudal centra (Figs 1, 3). Neural spines, haemal spines and ribs are well preserved, and some epineurals and epipleurals can also be distinguished. The first three abdominal centra are obscured by overlying material, but can be identified based on their corresponding neural spines. Each centrum is deeper than long.

Each centrum bears a neural arch with an elongated neural spine. The most anterior spines are quite short, but become successively longer in the middle of the column, with the neural spine of the last abdominal centrum being the longest. Transverse processes can be seen on the last six abdominal vertebrae. They are successively longer and thicker posteriorly. Haemal arches of the caudal vertebrate bear elongated spines. The first three haemal spines are long, broad and closely associated with each other. The more posterior haemal spines are much narrower and become successively shorter posteriorly. All neural and haemal spines appear to be fused to the their respective centra except for the haemal spines of the second and third preural centra. These two haemal spines also support some of the procurrent rays of the ventral caudal fin skeleton. Further detail concerning the most posterior vertebrae is given in the section on the caudal fin skeleton below.

Ribs are present on the transverse processes of the abdominal vertebrae. The ribs are long and gently curved, and each rib bears a groove along its length.

Some epineurals and epipleurals are present, although they are poorly preserved and incomplete. Epineurals from the right side can be seen on some of the more posterior abdominal vertebrae (vertebrae 8–11), and also the first caudal vertebra, although there may have been more in life. The epineurals originate on the neural arches of corresponding vertebrae. They all appear to originate from a similar level, although this cannot be clearly seen, as they are not from the exposed side of the specimen. The epipleurals appear to originate on the haemal arches of the first three caudal vertebrae and the transverse processes of the last abdominal vertebra.

There are three supraneurals arranged in the following predorsal formula: 0+0+0/x+x/. The third supraneural is incomplete, with only the dorsal and ventral parts remaining. All three are of a similar length, and each is expanded distally to form an enlarged head.
**Median fins.** The dorsal, anal and caudal fins are preserved in articulation (Figs 1, 3). The dorsal fin is supported by 32 pterygiophores. The first pterygiophore is distinct from the others with its sickle-shaped head. The first and second pterygiophores insert in the space between the first and second neural spines. Subsequent pterygiophores insert individually (3–7, 12), in pairs (8–11, 13–24, 31–32) and in triplets (25–30) between neural spines. Pterygiophores decrease progressively in size toward the posterior of the series. There are three fin spines in the dorsal fin; they articulate with the first three pterygiophores. The length of successive fin spines increases, with each spine being approximately twice the length of that preceding it. There are 22 rays visible posterior to the spines. However, quality of preservation deteriorates posteriorly, and the absence of rays from posterior radials is almost certainly an artefact. The first ray is extremely long, but the subsequent rays are substantially shorter. The first ray is segmented, but this cannot be seen on any of the other rays. Most of the rays are incomplete distally; after the tenth ray, they can only be identified by the most proximal sections. No branching can be seen on the rays. The spines and rays are articulated in a 1:1 ratio with the pterygiophores. It appears that the number of pterygiophores present represents the true number, so there would have likely been 29 rays in life.

The anal fin comprises 22 pterygiophores, three spines, but only 17 rays are preserved. Some of the rays in the middle and posterior of the fin are not preserved. The first pterygiophore ('hemaxanal complex') is the largest and most robust of the series, and has an anteriorly pointing, sickle-shaped hook at its ventral end. The other pterygiophores are substantially shorter and narrower. They are all of a similar height, although there is a slight decrease toward the end of the series. The first anal-fin spine is very small, with the second spine 2.5 times the size of the first, and the third spine twice the size of the second. The first, second and possibly third spines articulate with the first pterygiophore. As with the dorsal fin, the preservation quality of the rays deteriorates posteriorly. The first and second rays are successively longer than the third spine. Distal parts of the rays are missing starting with the third ray, so it is not possible to comment on the full extent of their length. The rays appear to be in a 1:1 ratio with the pterygiophores. It seems likely that there would have been approximately 20 rays in life.

The caudal fin contains 11 procurrent (six dorsal, five ventral) and 19 principal rays (10 dorsal, nine ventral), with a formula of 6+1+9/8+1+5. The shorter outermost procurrent rays and some of the principal rays where the dorsal and ventral lobes meet do not bifurcate. The first and last principal rays do not bifurcate. Two of the principal rays in the dorsal lobe bifurcate twice. All other rays bifurcate once. All rays except the most anterior procurrent rays show some degree of segmentation. With the exception of the first and the last, all principal rays are segmented once proximally. This segmentation is more conspicuous than anywhere else in the caudal fin, and similar to the condition seen in other lampridomorphs (e.g. †Zoqueichthys; Alvarado-Ortega & Than-Marchese 2012, fig. 6). Some of the principal rays are also segmented distally. No rays appear to be segmented along their length. There is considerable overlap of the rays with the hypurals of the caudal skeleton.

The caudal fin skeleton includes the second and third preural centra, the pseudourostylar complex, three epurals, two uroneurals, six hypurals and one parhypural. The neural and haemal spine of the third preural vertebra are both elongated. The neural spine articulates with the first two procurrent rays of the dorsal lobe. The haemal spine articulates with the first three procurrent rays of the ventral lobe. The haemal spine of the second preural vertebra articulates with the procurrent rays, but its small, leaf-shaped neural spine articulates with the first epural. The epurals are bound closely together. The first is the longest, with the other two successively shorter. Details of the pseudourostylar complex (the first preural plus first ural vertebra) are
difficult to discern. It is unclear whether a second ural vertebra was present. The first uroneural
is associated with the dorsal part of the pseudourostylar complex. This is in articulation with the
second uroneural, which articulates with the last of the dorsal recurrent rays. Ventrally, the
pseudourostylar complex articulates with the parhypural. The parhypural articulates with the first
two principal rays of the ventral lobe. It is closely associated with the first hypural, but is not fused
to it. A large part of hypural three and some of hypural two are missing. Hypural one is large and
plate-like, articulating with the majority of the principal rays of the ventral lobe. Hypural two is
much smaller, and articulates with a single ray. Only the proximal parts of the first and second
hypurals are fused to one another. It is unclear whether they were also fused to the
pseudourostylar complex. Fusion between other hypurals is not apparent, although it is hard to
distinguish the borders of the distal parts of the third and fourth hypurals. The third hypural is a
large plate-like bone, and may have been larger than the first hypural if complete. The fourth
hypural is also plate-like, although smaller than the previous. Hypurals five and six are
substantially smaller and shorter than any of the others.

**Paired fins and girdles.** The preserved components of the pectoral girdle are incomplete and represent bones from both the right and left sides of the specimen (Figs 1–2). No supratemporal can be seen. The body of the posttemporal is circular with a dorsal arm overlying the epiotic and a small remnant of the ventral arm.

Both the left and right supracleithra and cleithra are preserved. Each supracleithrum is tall and smooth with a large dorsoventral groove on its external surface.

Of the two cleithra, the right one is the most complete. They are tall bones, and preserved dorsally only as thickened ridges representing the anterior margins of the bones. Ventrally, there is a large plate-like posterior process. All parts of the cleithra appear unornamented.

The medial surface of the scapula, coracoid and postcleithrum of the right side is visible. Little of the scapula is visible, and the connection between it and the coracoid is hard to discern. The ventral part of the coracoid is broken, but the dorsal part is complete and appears to articulate with part of the cleithrum under the plate-like expansion. Part of the dorsal postcleithrum is preserved. The anterior margin is intact and bears a thickened ridge. The posterior margin of the dorsal postcleithrum is broken and incomplete. No part of the ventral postcleithrum can be seen. The pectoral girdle articulates with four distinct pectoral radials collectively bearing 12–14 pectoral rays. Only the proximal ends of the rays are visible as dorsal postcleithrum obscures distal parts of the fin.

The pelvic girdle is not preserved.

**Squamation.** There appear to be a few ventral ridge scales preserved along the lower margin of the hemaxanal complex (Fig. 1). The form of the scales is not clearly visible.

Genus †'Aipichthys' Steindachner, 1860

†'Aipichthys nuchalis' (Dixon, 1850)

(Figs 4–7)

1850 †*Microdon nuchalis* Dixon: 369, pl. 32, fig. 7.

1887 †*Platax* (?) *nuchalis* (Dixon); Woodward: 342.

1901 †*Aipichthys nuchalis* (Dixon); Woodward: 429.

1902 †*Aipichthys nuchalis* (Dixon); Woodward: 4.

1964 †*Aipichthys nuchalis* (Dixon); Patterson: 303.
**Diagnosis.** Lampridomorpha with only the supraoccipital contributing to the sagittal crest; unlike †'Aipichthyoididae', †Nardovelifer and Lampridiformes where the frontal also contributes to the structure. The crest has a thickened anterior margin and a concave posterior margin. This condition is the same as is found in †*Freigichthys*, †*Gigapteryx* and other species of †'Aipichthys'. Has 11 abdominal vertebrae like †'A.' *velifer*, †'A.' *minor* and †*Freigichthys*. Body of greater depth than is known for †*Freigichthys* or any other species of †'Aipichthys' (Table S2).

**Material.** The Holotype and only known specimen. NHMUK PV OR 25770, an incomplete and partially articulated skeleton.

**Occurrence.** Upper Cenomanian English Chalk. According to Dixon (1850), the holotype was found in a chalk pit near Washington, Sussex, United Kingdom. It was likely from either the Zig Zag Chalk Formation of the Grey Chalk Subgroup or the Holywell Nodular Chalk Formation of the White Chalk Subgroup (Hopson 2005). Woodward (1902, p. 5) states the specimen is probably from the 'zone of *Holaster subglobosus*', although the exact horizon was not recorded when the specimen was collected. The zone of †*Holaster subglobosus* does not fully correspond with modern zones, and is represented by the lower part of the †*Neocardioceras judii* and the upper part of the †*Acanthoceras rhotomangense* zones (Caldwell 1999). The range of these zones is 93.49–94.86Ma (Hardenbol *et al.* 1998).

**Description**

The exposed right side of the specimen (Fig. 4) consists of broken sections through bones, and shows poor detail, leaving many of the anatomical features hard to discern. The following description is primarily based on features from the unprepared left side as observed in CT models (Fig. 5) unless otherwise specified.

**Measurements and meristics.** The specimen is incomplete posteriorly and measures 22 mm from the anterior edge of the frontal to the last preserved caudal vertebra. It likely would have been between 23–25 mm standard length in life based on an extrapolation of measurements of †'A.' *minor* and †'A.' *velifer* (Table S2). There are 11 abdominal vertebrae and 11 preserved caudal vertebrae; additional caudal vertebrae would have been present in life as there is no trace of the caudal skeleton. The median fins are represented by a small number of elements: 10 pterygiophores from the dorsal fin, plus two fin spines and a pterygiophore from the anal fin. Much of the pectoral girdle is preserved, although only two fin rays are preserved. The two pelvic bones are present, but poorly preserved.

**Skull.** The skull (Figs 4–6) is incomplete and some regions, especially the posterior section, appear to be compressed. Identifiable bones include the frontal, supraoccipital, parietal, pterotic, orbitosphenoid, parasphenoid, nasal and lateral ethmoid.

The frontal occupies much of the anterodorsal region of the skull, forming the anterior roof of the skull and framing the dorsal margin of the orbit. The frontal is fractured in a number of places, and the posterior section of the frontal is severely crushed. The dorsolateral margin of the orbit forms a lateral supraorbital shelf, which has a fully ossified sensory canal. Otherwise, the dorsal surface of the bone is smooth, and does not contribute to the sagittal crest of the skull. Instead, this conspicuous feature is formed exclusively by the supraoccipital. This bone forms a tall crest with a slight concave curve to the posterodorsal margin. The surface of the crest is smooth and flat with the exception of a thickened ridge along its anterior margin.

The parietal is incompletely preserved. A ledge-like facet at the anterior end of the bone appears to mark the articulation with the supratemporal. This facet originates at the top of what
remains of the anterior end of the parietal, extends in a posteroventral direction before turning roughly 80 degrees and continuing anteriorly before terminating.

The incomplete pterotic preserves a surprising amount of anatomical detail. It bears an ovoid process on its ventral face, which has been interpreted as an attachment point for branchial elevators in other †'aipichthyoids' (Otero & Gayet, 1996, pp. 320–321). A gutter for a sensory line extends along the length of the dorsal surface of the bone, and exits the lateral surface of the bone. It is not clear whether this exit assumes the form of an open groove or a dorsally enclosed foramen.

The poorly preserved orbitosphenoid partially separates the orbits. The parasphenoid is a long, straight bone, with a fracture in the orbital region dividing the bone in two. The posterior end of the parasphenoid is poorly preserved, and shows some traces of the ascending process. No part of the parasphenoid is preserved posterior to the orbit. Anterior to the fracture, the parasphenoid is only visible on the right side of the fossil, although it is crushed against the lacrimal so little detail can be discerned. Overlying fragments of bone completely obscure the anterior end of the parasphenoid.

The long, thin nasal has been displaced and extends anteroventrally from the surface of the supraorbital shelf of the frontal and terminates adjacent to the premaxilla. The lateral ethmoid has been displaced to overlie the nasal. It is incompletely preserved and presumably would have been larger in life.

**Jaws.** The premaxilla, maxilla and possibly a supramaxilla of the upper jaw are preserved (Figs 4–6). Both premaxillae are displaced from life position. The more complete right premaxilla is found on the left side of the specimen in external view, while the ascending process of the left premaxilla – the only remaining preserved component of the bone – is on the right side of the specimen. The premaxilla has a tall, slender ascending process and a distinct, shorter articular process, and is approximately half the height of the ascending process. The length of the alveolar process is nearly equal to the height of the ascending process, although the alveolar process is incomplete posteriorly so it presumably would have been longer in life. Small teeth are visible along the oral margin of the bone. The maxilla consists of a plate-like posterior half that assumes a semi-circular shape. The bone narrows considerably near its anterior end, which is produced as an arm-like extension. The anterior end of the maxilla is obscured by unidentifiable fragments of bone. The maxilla is oriented at a steep angle, suggesting an upturned orientation of the mouth. It is possible that there is a supramaxilla on the dorsal surface of the maxilla. There is no clear margin to distinguish between the two, but if there were just one bone, the maxilla would be much deeper than in other species of †'Aipichthys'.

Both sets of the lower jaws are present, although the left mandible is more complete (Figs 4–6). Both jaws have rotated posteroventrally relative to life position. The jaws are triangular in shape. The dentary bears small teeth along its dorsal margin. Posteriorly, the dentary is 'V'-shaped where it articulates with the anguloarticular. The coronoid process projects from the posterodorsal apex of the jaw, and is composed of the upper limb of the dentary and the anguloarticular. There is a facet on the posteroventral corner of the anguloarticular where the lower jaw articulates with the quadrate. No retroarticular can be seen. A series of elongated pores for the mandibular sensory canal extend along the dentary above its ventral margin. The preservation of these structures becomes less clear posteriorly, so an exact count of pores is not possible. However, at least two pores were present.

**Infraorbital series.** The infraorbital series is represented by the lacrimal and presumably the second and third infraorbitals, which together define the ventral margin of the orbit (Figs 4–6).
The lacrimal is large and ovoid. The margin of the lacrimal is hard to detect as it has been compressed onto underlying structures, but its lateral surface does not appear to have been smooth. There is a well-developed process on the dorsolateral surface of the lacrimal. The process has a number of projections radiating distally along the surface of the lacrimal, with an ascending process protruding over the dorsal margin of the bone. These radial projections would have presumably housed the underlying sensory canal. The second and third infraorbitals are narrow bones, with a groove for the sensory line on the external surface. They lie in sequence posterior to the lacrimal, with the second infraorbital being slightly larger than the third.

**Suspensorium.** The only bones of the suspensorium that are preserved well enough to merit description are the hyomandibula, quadrate, endopterygoid and palatine (Figs 4–6). The splint-like hyomandibula extends ventrally from its articulation with the skull. It bears a large dorsal articular facet and carries a lateral ridge that extends most of the length of the bone. A plate-like process extends from the anterior margin of the hyomandibula, but appears to be incomplete. The quadrate is shaped like an elongated triangle. The quadrate narrows towards the anteroventral apex, where it bears a well-developed articular condyle. The endopterygoid and palatine can only be seen in medial view on the exposed side, as both the lacrimal and the parasphenoid obscure them from view on the other side. The endopterygoid appears to take the form of an oval, elongated along the anterior–posterior axis. The palatine is medial to the endopterygoid. Both the anterior and posterior ends of the palatine are not preserved. Both bones bear small teeth.

**Opercular series.** The opercular series is preserved only on the left side, where it consists of the opercle, preopercle and interopercle (Figs 4–6). The opercle is incomplete, with large areas of the posterior and dorsal margins missing, and the remaining dorsal half of the bone crushed against the medial face of the preopercle. The bone is flat with a generally smooth surface. The preopercle has a long thin dorsal arm and a short anteroventral arm forming a boomerang shape, with a slightly obtuse angle of 110 degrees between the two arms. The ventral portion of the preopercle is well preserved, but the preservational quality deteriorates dorsally, where little detail can be discerned. The underlying sensory canal is accommodated by a flange along most of the length of the lateral surface. However, two pores can be seen where the dorsal and anteroventral arms meet. The interopercle is positioned ventral to the preopercle. This bone is incomplete and poorly preserved along the exposed ventral margin. The interopercle is flat with a fairly smooth surface.

**Ventral hyoid arch and gill skeleton.** Two branchiostegals and the anterior ceratohyal are preserved, although these are partially concealed by overlying bones (Figs 4–6). The two branchiostegals are positioned along the ventral surface of the lower jaw. They are thin and curved. The posterior branchiostegal is longer than the other, although the anterior one appears to be broken. The anterior ends of the branchiostegals are obscured from view by the lower jaw. Both ends of the anterior ceratohyal are obscured, but it is clearly a long bone. A groove for the hyoid artery extends along the length of the bone. No 'beryciform' foramen can be seen.

**Axial skeleton.** The vertebral column is incomplete with much of the caudal section missing (Figs 4–5). Altogether there are 22 centra present, 11 abdominal and 11 caudal. The first three abdominal centra are obscured from view on the left side and undetectable from the right side, but can be identified based on their well-developed neural spines. Preservation of the vertebral column deteriorates posteriorly, with the most posterior vertebrae very incomplete. The anterior
and posterior ends of the individual centra are circular in section with deeply concave articular surfaces as seen on centrum seven, which has rotated to clearly show the articular facet. Fine bony laminae occupy the lateral surfaces of the centra and separate them into upper and lower cavities.

Many of the neural spines are broken and incomplete, but spines become increasingly longer until the seventh vertebra. Posterior to this point, neural spines become successively shorter. Haemal arches are present on the first nine caudal centra, but complete spines are only preserved on the first two caudal centra. The spines project posteroventrally from the centra.

Broken fragments of pleural ribs are associated with some of the centra.

No intermuscular bones are visible, but this might reflect resolution limits of the scan. No supraneurals are preserved.

**Median fins.** The fins are incompletely preserved, and many components that are present are displaced (Figs 4–5). Ten long pterygiophores are all that remains of the dorsal-fin skeleton. It is not clear where the first radial would have inserted. An anal-fin ray is preserved, although distally it is incomplete. There is a large, thick hemaxanal complex with an anteriorly facing sickle-like hook at its ventral apex. Two anal-fin spines are preserved. The first of these spines is one of the smaller anterior spines, which is found in articulation with the hemaxanal complex. The second spine is much larger than the first, and it has a sulcus running along the posterior margin.

**Paired fins and girdles.** The posttemporal is preserved only on the left hand side of the specimen, whereas the other preserved elements of the pectoral girdle are represented by right and left bones that have been shifted posteriorly and rotated to the left (Figs 4–5).

The posttemporal overlies the skull dorsal to the hyomandibula and the preopercle. The main body of the posttemporal is circular and smooth, and bears a long anterodorsal process that would have articulated with the epiotic.

Only the left supracleithrum is preserved. It assumes the shape of an elongated oval, with a thick ridge extending along the anterior margin of the lateral surface. Cleithra from both sides of the specimen are preserved, although both are incomplete. The cleithrum is dorsoventrally elongated and terminates dorsally with a narrow apex. Ventral ridge scales obscure the ventral tips of both cleithra. The lateral surface of the cleithrum has a raised ridge along the anterior margin. A robust rod-like ventral postcleithrum is preserved on the prepared side. A dorsal postcleithrum also appears to be preserved on this side.

Only the left coracoid can be clearly identified, where it is associated with the posterior margin of the left cleithrum. It is incompletely preserved, with only the posterior section present. The coracoid is an elongated bone with a raised posterior margin. Dorsally, the coracoid curves anteriorly, to form a large fenestra.

Two poorly preserved fin rays represent the only remains of the pectoral fin.

On the exposed side of the specimen, the two pelvic bones appear to be joined by the medial processes (Figs 4, 7). One half of the pelvis is highly incomplete, with only remnants visible, but most of the posterior section of the other half is present. The pelvic bones are triangular, and taper toward a point anteriorly. Posteriorly, each bone has a short posterior process medial to an articular facet for the pelvic-fin rays. The two pelvis bones diverge anterior to the medial process.

**Squamation.** There are a small number of thickened ventral ridge scales preserved below the pectoral girdle (Figs 4–5). Most of the scales have been crushed, but the scales are clearly ctenoid sensu lato, having a toothed posterior edge. No other scales are preserved in this specimen.
## Phylogenetic relationships

We used the matrix presented by Davesne *et al.* (2014) as the basis of our analysis, and included seven new characters (Table S1) and four new species. We were able to code the states of 45 characters for †*Aipichthys pretiosus*, 28 characters for †‘*Aipichthys*’ *nuchalis*, 60 characters for †*Gigapteryx* and 54 characters for †*Nardovelifer* (Table S3). The branch and bound analysis retained 29 trees, from which a strict consensus tree was produced (Fig. 8; tree length = 183 steps, consistency index = 0.45, homoplasy index = 0.55, retention index = 0.70, rescaled consistency index = 0.31).

The topology we recovered here is considerably different to that of Davesne *et al.* (2014). Instead of the lampridomorphs being split into two clades (Clades B and C sensu Davesne *et al.* 2014), they are united into one large clade. The internal branching structure of the Lampridomorpha highlights how character evolution may have occurred along the backbone of this clade. However, as with the topology of Davesne *et al.* (2014), many of these clades are weakly supported by Bootstrap and Bremer indexes (Fig. 8).

Our analysis shows that †*A. pretiosus*, the type species for †*Aipichthys*, is not closely related to other species attributed to the genus, and in fact has greater affinity to the †‘*Aipichthyoididae*’. The inclusion of †*A. pretiosus* and †*Nardovelifer* helps to resolve the polytomy between †*Aipichthyoides*, †*Aspesaipichthys* and crown Lampridiformes. Whilst †‘*Aipichthys*’ *velifer* and †*Freigichthys* were resolved as sister taxa in the original analysis, they are placed in a polytomy with †‘*A.*’ *nuchalis*, †‘*Aipichthys*’ *minor* and †‘*Aipichthys*’ *oblongus* in this analysis. We also find that †*Gigapteryx* and †*Pycnosteroides* are united as sister taxa, and collectively they are the most deeply branching lampridomorphs.

Below is a breakdown of the major clades – and the synapomorphies that define them – that were recovered in our phylogenetic analysis. When discussing synapomorphies presented by Davesne *et al.* (2014) we do not discuss them in detail (e.g. character state reversals within a clade) unless they are new characters, or when changes we have made to the character matrix have resulted in different character optimizations. The clade names used below correspond with the names from Fig. 8.

## Acanthomorpha

We found nine characters that are synapomorphies of Acanthomorpha. These include all eight synapomorphies proposed by Davesne *et al.* (2014): the frontal branch of the sensory canal opening in a groove (character 14: 0 → 1), a developed sagittal crest (character 16: 0 → 1), the dorsal limb of the posttemporal is firmly bound to the epiotic (character 22: 0 → 1), dorsal-fin spines (character 42: 0 → 1), presence of a hemaxanal complex (character 46: 0 → 1), anal-fin spines (character 47: 0 → 1), urodermals absent (character 56: 0 → 1) and dermal caudal scutes absent (character 57: 0 → 1). The anterior epineurals originating on the centra or transverse processes (character 35: 0 → 1) was considered a synapomorphy of Euacanthomorpha by Davesne *et al.* (2014), which had convergently evolved in †*Pycnosteroides* Woodward, 1942 + †*Pharmacichthys* Woodward, 1942. Changes in the topology of our tree suggest this character is diagnostic for Acanthomorpha and was reversed in Clade β.

We found strong support for the placement of our four additional taxa within Acanthomorpha. We found eight synapomorphies in †*Gigapteryx* (characters 16: 1, 22: 1, 35: 1, 42:1, 46: 1, 47: 1, 56: 1, 57: 1), four in †‘*A.*’ *nuchalis* (characters 14: 1, 16: 1, 46: 1, 47: 1), seven in †*A. pretiosus* (characters 14: 1, 16: 1, 42: 1, 46: 1, 47: 1, 56: 1, 57: 1) and six in †*Nardovelifer* (characters 16: 1, 42: 1, 46: 1, 47: 1, 56: 1, 57: 1). The character states of the other acanthomorph
synapomorphies could not be determined, except one character in †A. pretiosus (character 35: 0), which is optimized as a reversal in Clade β.

## Clade A: Lampridomorpha

Davesne *et al.* (2014) proposed nine synapomorphies for Lampridomorpha. We recovered four of these characters as unambiguous synapomorphies for lampridomorphs: absence of the antorbital (character 7: 0 → 1), a single articular head of the hyomandibula (character 25: 0 → 1), first dorsal pterygiophore inserts anterior to the second neural spine (character 40: 0 → 1) and contact between the coracoid and the pelvic girdle (character 63: 0 → 1). Two of the lampridomorph synapomorphies of Davesne *et al.* (2014) were not unambiguously supported as lampridomorph synapomorphies. Firstly, an ascending process of the lacrimal (character 8: 0 → 1) is not present in †*Pharmacichthys* but found in all of the other deeply branching lampridomorph lineages. This character can be optimized as either a lampridomorph synapomorphy with a reversal in †*Pharmacichthys*, or as convergently evolved in †*Pycnosteroides* + †*Gigapteryx* and Clade β. Secondly, hypurostegy of the caudal-fin rays (character 58: 0 → 1) is present in Myctophiformes and most lampridomorphs but absent in Euacanthomorpha, so it could be optimized as a reversal in Euacanthomorpha or homoplastic in myctophiforms and lampridomorphs. With the changes to the topology of the tree, we found that two of the lampridomorph synapomorphies (characters 39: 0 → 1, 43: 0 → 1) proposed by Davesne *et al.* (2014) are synapomorphic of Clade α. A medial join between the internal wings of the pelvic bones (character 64: 0 → 1) was also considered to be a synapomorphy of lampridomorphs by Davesne *et al.* (2014). However, the states of this character could not be determined in †*Pharmacichthys*, †*Pycnosteroides* and †*Gigapteryx*, so it is unclear whether the character is diagnostic of Lampridomorpha or one of the constituent clades instead. We also recovered three additional characters as synapomorphies for lampridomorphs. These included a concave posterior edge of the sagittal crest (character 19: 0 → 1), seven pelvic fin rays (character 66: 0 → 2) and loss of the suborbital shelf (character 72: 1 → 0). For two of these characters, the states change higher up in the tree. Character 19 reverses back to the ancestral state (1 → 0), whilst character 66 is homoplastic in †*Freigichthys* (2 → 1) and Clade C, where the optimization is ambiguous (2 → 0 or 2 → 1).

All seven of the unambiguous synapomorphies are present in †*Gigapteryx*. Three and two respectively are present in †‘A.’ *nuchalis* (characters 19: 1, 25: 1, 72: 0) and †A. pretiosus (characters 25: 1, 40: 1). States for the other synapomorphies in these two taxa could not be determined. †*Nardovelifer* has four synapomorphies (characters 7: 1, 19: 1, 63: 1, 72: 0), although the state for character 19 is homoplastic, as †*Nardovelifer* is placed within Clade C where there is a reversal to the ancestral condition. Two of the character states found in †*Nardovelifer* (characters 40: 2, 66: 1) differ from those diagnostic of lampridomorphs, as †*Nardovelifer* is placed high in the tree where different character states are found. The state of character 25 could not be determined in †*Nardovelifer*.

## Clade α

Clade α is a new unnamed clade recovered from our analysis and includes all lampridomorphs except †*Pycnosteroides* + †*Gigapteryx*. This clade is supported by two synapomorphies that were previously considered to be synapomorphies of lampridomorphs by Davesne *et al.* (2014). The two characters are: all supraneurals anterior to the first neural spine (character 39: 0 → 1) and an elongated and unbranched first soft ray of the dorsal fin (character 43: 0 → 1).

†*Gigapteryx* does not have one of the synapomorphies of Clade α (character 39: 0), whilst the state could not be determined for the other character. The placement of †*A. pretiosus* and
†Nardovelifer within Clade α was well supported, as the two synapomorphies were present in both taxa. The states of the two synapomorphies could not be determined in †'A.' *nuchalis*.

## Clade β

The new unnamed clade, Clade β, contains all lampridomorphs except †*Pycnosteroides* + †*Gigapteryx* and †*Pharmacichthys*. We identified three synapomorphies that unite the included taxa: absence of a 'beryciform' foramen (character 27: 0 → 1), the anterior epineurals originating on the neural arches or spines (character 35: 1 → 0) and ventral ridge scales present (character 74: 0 → 1). Ventral ridge scales are lost higher up the tree in Clade δ.

Two synapomorphies are present in both †'A.' *nuchalis* (characters 27: 1, 74: 1) and †A. *pretiosus* (characters 35: 0, 74: 1), whilst the other character state could not be determined. †Nardovelifer only has one synapomorphy present (characters 27: 1), as one of the other characters was missing; absence of the final character was optimized as a reversal for Clade δ, which †Nardovelifer is part of.

## †'Aipichthys' + †Freigichthys

Within Clade β, the deepest branch is a polytomy containing all four species of †'Aipichthys' + †*Freigichthys*. The genera †'Aipichthys' and †*Freigichthys* are defined by three synapomorphies: reduction to one supramaxilla (character 3: 0 → 1), presence of an interfrontal flat (character 13: 0 → 1) and a thickened anterior edge of the sagittal crest (character 21: 0 → 1). †'A.' *nuchalis* has a thickened anterior edge of the sagittal crest, but the states of the other two characters could not be determined. In this analysis, †'Aipichthys' and †*Freigichthys* are placed in a polytomy. In the original analysis of Davesne *et al.* (2014) some of the relationships were defined by a homoplastic character: the preopercular sensory canal in the pterotic opening laterally through an indentation in †'A.' *velifer* and †*Freigichthys* (character 15: 1), but opening through a pore in †'A.' *oblongus* and †'A.' *minor* (character 15: 0). As this character state could not be determined in †'A.' *nuchalis*, the relationships between these taxa are not resolved further in this phylogenetic analysis.

## Clade C

In our analysis we recovered Clade C of Davesne *et al.* (2014). This clade is supported by three synapomorphies: two previously described by Davesne *et al.* (2014) and one additional character. The three characters are: the frontal forms part of the sagittal crest (character 17: 0 → 1), the crest has a convex posterior border (character 19: 1 → 0) and the crest is long, extending from the nasal to the occiput (character 20: 0 → 1). Davesne *et al.* (2014) found that Character 19 was a synapomorphy of their Clade B. Clade B was not recovered in our analysis.

Both †A. *pretiosus* and †Nardovelifer have a long sagittal crest (character 20: 1). The frontal forms part of the crest of †A. *pretiosus* (character 17: 1). The crest of †Nardovelifer is broken in a number of places, so it is unclear whether the frontal forms part of this structure. The sagittal crest of †Nardovelifer has a convex posterior border (character 19: 1), and this appears to be homoplastic. The posterior border of the crest is missing in †A. *pretiosus*.

## Clade D

Clade D contains all the taxa of Clade C except †*Zoqueichthys* Alvarado-Ortega & Than-Marchese, 2012. In the original analysis of Davesne *et al.* (2014) †*Aipichthyoides*, †*Aspesaipichthys* and crown Lampridiformes are placed in a polytomy, but with the additional taxa and characters here, the relationships are resolved. Davesne *et al.* (2014) recovered three characters that support Clade D. We found that two of these characters supported Clade D in our analysis: the
mesethmoid located medially or posteriorly to the lateral ethmoids (character 6: 0 → 1) and fusion of the lower hypurals (character 54: 0 → 1). The first character state could not be determined in †A. *pretiosus*, but is present in †*Nardovelifer*. The lower hypurals are not completely fused in †A. *pretiosus*, but are fused proximally and free distally, in the manner Otero & Gayet (1996) described for the †'Aipichthyoididae' (e.g. Davesne *et al.* 2014, fig. 3b). In †*Nardovelifer* the lower hypurals are fused in the middle region, but not proximally or distally. In our analysis we did not find support for the third synapomorphy of Davesne *et al.* (2014) – having five or fewer hypurals (character 51: 0 → 1). Both †A. *pretiosus* and †*Nardovelifer* have six hypurals, not five. Within Clade D, it now seems likely that six hypurals is the ancestral state, as †A. *pretiosus*, †*Nardovelifer*, *Metavelifer* and *Velifer* also show the general condition of six hypurals (Oelschläger 1983). It appears that both †*Aipichthyoides* + †*Aspesaipichthys* and *Lampris* + *Trachipterus* + *Regalecus* convergently lost the sixth hypural. Thus possessing five or fewer hypurals should no longer be considered a synapomorphy of Clade D.

## Clade γ

Clade γ is another new unnamed clade, uniting †A. *pretiosus* and †*Aipichthyoides* + †*Aspesaipichthys*. This clade has one synapomorphy: the mesethmoid forming part of the sagittal crest (character 18: 0 → 1), which is present in †A. *pretiosus* and †*Aipichthyoides*, although this character is unknown in †*Aspesaipichthys*. The fusion of the lower hypurals to the pseudourostylar centrum (character 55: 0 → 1) is a possible character shared by these three taxa. In both †*Aipichthyoides* and †*Aspesaipichthys*, the lower hypurals are fused to the pseudourostylar centrum, but this state cannot be determined in †A. *pretiosus*, so it could be an exclusive synapomorphy of †*Aipichthyoides* + †*Aspesaipichthys*, or unite all three taxa. There is only one synapomorphy that unites †*Aipichthyoides* and †*Aspesaipichthys*, but excludes †A. *pretiosus*: the presence of five or fewer hypurals (character 51: 0 → 1).

## Clade δ and Lampridiformes

Davesne *et al.* (2014) recovered 14 synapomorphies for Lampridiformes. We found that some of these characters are synapomorphies of another clade, Clade δ, where †*Nardovelifer* is the sister taxon to crown Lampridiformes. There are seven synapomorphies for Clade δ. These are: the ascending process of the premaxilla is longer than the alveolar process (character 2: 0 → 1), supramaxillae are absent (character 3: 0 → 2), there are seven or fewer branchiostegals (character 28: 1 → 2), the first dorsal pterygiophore is anterior of the first neural spine (character 40: 1 → 2), the upper hypurals are fused together (character 52: 0 → 1), absence of an articular process on the premaxilla (character 69: 1 → 0) and loss of the ventral ridge scales (character 74: 1 → 0). †*Nardovelifer* has all of these synapomorphies. Five of these characters (characters 2, 3, 28, 40, 52) were previously recognized as synapomorphies of Lampridiformes by Davesne *et al.* (2014), while the two other characters (characters 69, 74) are new additions to the matrix. †*Nardovelifer* is also united with *Lampris*, *Regalecus* and *Trachipterus* by a reduction to three pectoral fin radials (character 62: 0 → 1). However, *Velifer* has four radials, so the reduction to three radials could either be a synapomorphy with a reversal in veliferids, or it may have evolved independently in †*Nardovelifer* and crown Lampridiformes excluding veliferids. A reduction from three to two supraneurals (character 38: 0 → 1) could also be diagnostic of Clade δ. Three supraneurals is the primitive condition for acanthomorphs, but crown Lampridiformes have two or fewer supraneurals. All the crown lampridiforms in our analysis have one or fewer supraneurals, but some veliferids have two supraneurals.

The crown lampridiforms are united by five characters. Two of these were considered synapomorphic by Davesne *et al.* (2014): the upper hypurals are fused to the second ural centrum
(character 53: 0 → 1) and the dorsal and ventral postcleithra are fused together (character 61: 0 → 1). The final three characters are new additions: dentition is absent on the premaxilla (character 68: 0 → 1), dentary (character 70: 0 → 1) and endopterygoid (character 71: 0 → 1). Two of these characters are not optimized as unambiguous synapomorphies: the absence of dentition on both the lower and upper jaws. Dentition is only present on the jaws in some of the elongated lampridiforms, which are typically recovered as a monophyletic group (Wiley *et al.* 1998; Grande *et al.* 2013). Therefore, the absence of dentition on the lower and upper jaws are either synapomorphies of Lampridiformes with the states reversed in the elongated forms, or jaw dentition was lost separately in veliferids and lamprids. †Nardovelifer has none of these lampridiform synapomorphies.

Four of the 14 Lampridiformes synapomorphies presented by Davesne *et al.* (2014) are either synapomorphies of Clade δ or the Lampridiformes. These characters are unknown in †Nardovelifer so it is not possible to say which of the two clades they are diagnostic of. The four characters are: absence of an ascending process of the lacrimal (character 8: 1 → 0), presence of a frontal vault or cradle (character 12: 0 → 1), no epineurals on the caudal vertebrae (character 36: 0 → 1) and no epipleurals (character 37: 0 → 1).

## Discussion

### The status of †Paraipichthys

†Paraipichthys lusitanicus, the only species of the genus, from Cenomanian deposits in Portugal was described and assigned to the †'Aipichthyidae' by Gaudant (1978). In the phylogenetic hypotheses of Otero & Gayet (1995, 1996), Otero (1997) and Alvarado-Ortega & Than-Marchese (2012) †Paraipichthys was recovered as the sister group to †'Aipichthys', while Davesne *et al.* (2014) found †Paraipichthys to be a more deeply diverging lampridomorph.

†Paraipichthys is only known from two specimens: the holotype (IST 561; Fig. 9A) and the paratype (IST 560; Fig. 9B). The holotype shows only the anterior part of the skeleton (cranium, opercles, pectoral and pelvic fins, anterior portions of the anal fin and vertebral column), however it is poorly preserved and only a few useful characters can be observed. By contrast, the paratype is a well-preserved caudal fin with several posterior vertebrae and part of a dorsal fin. The majority of the characters in previous phylogenetic analyses were coded from the paratype. However, there is no overlap between these two specimens; they are oriented differently and the paratype appears to be from a considerably larger animal than the holotype. Further to this, both the holotype and the paratype appear to be preserved in different sediments, and are possibly from different horizons. Therefore, we recommend that the paratype should be referred to as cf. †Paraipichthys, until new specimens can show overlap between the anterior and caudal regions of †Paraipichthys, and confirm whether the holotype and paratype represent the same genus and species. The few characters that could be coded from the holotype led us to remove †Paraipichthys from our analysis. If individually the holotype and paratype are consistent with a placement inside Lampridomorpha, their position relative to other lampridomorphs cannot then be determined with any confidence.

### †Aipichthys as a genus

Our analysis shows that †Aipichthys pretiosus is distinct from all other species that have been subsequently assigned to the genus †Aipichthys, and thus we now recommend those taxa (formerly known as †Aipichthys velifer, †Aipichthys minor, †Aipichthys oblongus and †Aipichthys nuchalis) should temporarily be referred to as †'Aipichthys' rather than †Aipichthys, which we reserve for †A. pretiosus. Under Article 60 of the International Code of Zoological Nomenclature
(International Commission on Zoological Nomenclature 2000), the junior homonym (i.e. †'Aipichthys') should be replaced by an established synonymous name or if one is not available then a new substitute name should be used. Both synonymous names for †Aipichthys are preoccupied: *Microdon* Dixon 1850 is preoccupied by an extant dipteran insect (family Syrphidae) and *Platax* Pictet 1850 is preoccupied by an unrelated extant acanthomorph (family Ephippidae). This and previous analyses (e.g. Alvarado-Ortega & Than-Marchese 2012; Davesne *et al.* 2014) show strong morphological similarity between †'Aipichthys' and †*Freigichthys*; it could be proposed that the concept of †*Freigichthys* could be expanded to accommodate species of †'Aipichthys'.

In †*Freigichthys* and †'A.' *velifer* the preopercular branch of the pterotic opens through an indentation, but it opens through a pore in the rest of †'Aipichthys'. This character has resolved some of the relationships amongst these taxa in previous studies (Alvarado-Ortega & Than-Marchese 2012; Davesne *et al.* 2014), but all species of †'Aipichthys' and †*Freigichthys* are placed in a polytomy here. Despite close morphological similarity between these two genera, †*Freigichthys* possesses a number of characters that distinguish it from †'Aipichthys'. These include: presence of seven rather than six pelvic fin rays, presence of a suborbital shelf that also includes the lacrimal, pterygiophores with smooth median laminae and spines with longitudinal ridges (Otero 1997). Overall, despite the close morphological similarity between †'Aipichthys' and †*Freigichthys* these taxa seem too dissimilar to incorporate into the same genus. Therefore we recommend the usage of †'Aipichthys' for †'A.' *velifer*, †'A.' *minor*, †'A.' *oblongus* and †'A.' *nuchalis* until the relationships between these taxa and †*Freigichthys* can be refined.

†Gigapteryx as a lampridomorph

†*Gigapteryx tethyestris* is the only species of the genus, and it is only known from one specimen (Fig. 10). However, in Forey *et al.* (2003) the figures are labelled as †*Gigapteryx tethyensis*, and in the abstract as well as on the holotype specimen itself, it has been named †*Gigapteryx lebanonensis*. Both of these species names appear to be erroneous. There are no other records of a †*G. tethyensis* and Forey *et al.* (2003) mention that †*G. tethyestris* is the only species of the genus. They also explain the origin of the name †*G. tethyestris* in text. In their paper, Forey *et al.* (2003) also describe another new genus and species: †*Paracentrus lebanonensis*. Presumably the authors have accidentally referred to †*Gigapteryx* using this species name, as they consistently refer to †*P. lebanonensis* in the text and only refer to †*G. lebanonensis* in the abstract. To summarize, †*G. tethyestris* is the only known species of †*Gigapteryx*, and both of the alternative names mentioned above should be disregarded.

When they originally described †*Gigapteryx*, Forey *et al.* (2003) placed it as Acanthopterygii *incertae sedis*. They identified one euacanthomorph synapomorphy from Johnson & Patterson (1993) in †*Gigapteryx*: the anterior epineural originating on the centrum, rather than the neural arch. However, they could not find any other euacanthomorph synapomorphies. They also identify two characters that suggest an affinity with acanthopterygians: presence of pelvic fin spines and a reduced number of pelvic fin radials. However, the authors did not consider whether †*Gigapteryx* was related to any of the taxa that we now refer to as lampridomorphs.

In our analysis, we find that †*Gigapteryx* is the sister taxon to †*Pycnosteroides*, and together they are sister taxa to all other lampridomorphs (Clade α). We found all nine of our lampridomorph synapomorphies in †*Gigapteryx*, and this clade was relatively well supported by Bootstrap and Bremer support indexes (Fig. 8). Furthermore, we believe that the characters identified by Forey *et al.* (2003) do not sufficiently justify an affinity to Euacanthomorpha or Acanthopterygii. The anterior epineurals originating on the centrum appears to be a
synapomorphy of acanthomorphs, rather than a synapomorphy of Euacanthomorpha as suggested by Johnson & Patterson (1993). The anterior epineurals originate on the centrum in †Pycnosteroides, †Gigapteryx and †Pharmacichthys – the most deeply branching lampridomorphs. In Clade ß, which excludes these three genera, there appears to be a character reversal where the anterior epineurals originate on the neural arches or spines. The presence of pelvic fin spines appears to be homoplastic for †Pycnosteroides + †Gigapteryx and acanthopterygians. However, some molecular phylogenies show Lampridiformes to be the sister group to the Euacanthopterygii (e.g. Near et al. 2013). If this is the case, the presence of pelvic spines could be a synapomorphy of Lampridomorpha + Euacanthopterygii, and subsequently lost in Clade α. Finally, we have not been able to find a description of the pelvic radials in any of the fossil lampridomorphs used in our analysis. In extant lampridiforms, at least some of the pelvic radials are typically cartilaginous (Olney et al. 1993). Therefore, we do not believe this character can be used to place fossil taxa relative to living groups, as it is impossible to say whether the number of radials preserved is the true number.

In light of the new evidence we have presented here, we recommend that †Gigapteryx should no longer be classified as Acanthopterygii *incertae sedis*. Instead, †Gigapteryx should be considered to be part of the Lampridomorpha.

†Nardovelifer as a stem lampridiform

†Nardovelifer (Fig. 11) is generally regarded as a member of the extant lampridiform radiation and placed within Veliferidae, despite showing a number of characters not present in other veliferids or indeed other lampridiforms (Sorbini & Sorbini 1999). As well as the characters identified by Sorbini & Sorbini (1999; dentition on the jaws and endopterygoid) we identified a number of primitive acanthomorph characters that exclude †Nardovelifer from veliferids specifically and crown lampridiforms generally. †Nardovelifer also retains the primitive condition of upper hypurals autogenous to the ural centra and postcleithra formed from two separate bones. On this basis of this evidence, we conclude that †Nardovelifer falls outside the lampridiform crown. In doing so, it helps to fill the structural gap between crown lampridiforms and the more distantly related †‘aipichthyoids’. Our reinterpretation of †Nardovelifer also revises the minimum age for the divergence between Veliferidae and other extant lampridiforms to the early Palaeogene, rather than the late Late Cretaceous as presented in Davesne *et al*. (2014, fig. 7).

The palaeobiogeography and palaeoecology of Cretaceous lampridomorphs

Lampridomorphs outside of Clade C are exclusively found in Cenomanian deposits. The deposits in Lebanon (Hakel, Hadjoula and Namoura) yield the most taxa from this clade, including †Pycnosteroides levispinosus (Hay, 1903) (Fig. 12A), †Gigapteryx (Fig. 10), †Pharmacichthys numismalis Gayet, 1980a (Fig. 12B), †Pharmacichthys venenifer Woodward, 1942 (Fig. 12C), †‘A.’ minor (Fig. 12D), †‘A.’ velifer (Fig. 12E), †‘A.’ oblongus and †Freigichthys (Fig. 12F). †Pharmacichthys judensis Gayet 1980b, and †‘A.’ nuchalis (Figs 4–7) derive from separate deposits in Palestine and England respectively. With the exception of the English Chalk, all of these deposits were of similar palaeolatitude. Within Clade C, some of the most deeply diverging branches represent Cenomanian taxa: †Zoqueichthys (Fig. 12H) from Mexico, †A. pretiosus (Figs 1–3) from Slovenia and †Aipichthyoides (Fig. 12H) from Palestine, but no examples from Lebanon. †Aspesaipichthys (Fig. 12I) is found in Campanian–Maastrichtian deposits from Nardò Italy, along with †Nardovelifer altipinnis (Fig. 11). Two *incertae sedis* lampridomorphs, †Errachidia pentaspinosa and †Homalopagus multispinosus Murray and Wilson, 2014, are also known from Cenomanian–Turonian deposits in Morocco. No crown lampridiforms are known from the
Cretaceous. The relative abundance of lampridomorphs from Lebanese sites might either indicate genuinely high diversity in these settings or reflect more exhaustive sampling. There appear to be collecting or preservation biases against small fishes in deposits like the English Chalk Group. It is possible that the rarity of lampridomorphs from these sediments represents taphonomic – rather than biological – signal.

With the exception of †Nardovelifer, lampridomorphs from the Cretaceous are morphologically very similar (e.g. Fig. 12): small (< 100 mm standard length), deep-bodied, with long, tall dorsal and anal fins, and have a moderately protusible premaxilla. †Nardovelifer is morphologically distinct (Fig. 11) and bears the greatest resemblance to the extant lampridiforms, especially the anatomically generalized veliferids. It is nearly an order of magnitude larger than other Cretaceous lampridomorphs (350 mm standard length), with a highly protusible premaxilla. Relatively large sizes and extreme jaw protrusion are two ecologically relevant features characteristic of crown lampridiforms. Our placement of †Nardovelifer on the lampridiform stem places the origin of these traits deeper within lampridomorph phylogeny than implied by previous interpretations of this genus as a crown lampridiform. The striking difference in habitus between early lampridomorphs on one hand and †Nardovelifer plus crown lampridiforms on the other suggests that future fossil finds might play an important role in further clarifying the sequence of evolutionary changes leading to the unusual lampridiform bodyplan.

## Acknowledgements

We wish to thank Zerina Johanson and Emma Bernard (Natural History Museum, London, UK), Ursula Göhlich (Naturhistorisches Museum, Vienna, Austria), Gäel Clément (Muséum national d'Histoire naturelle, Paris, France), Manuel Francisco Costa Pereira (Instituto Superior Técnico, Lisbon, Portugal) and Anna Vaccari (Museo Civio di Storia Naturale, Verona, Italy) for access to collections. We also thank Farah Ahmed, Zerina Johanson, Rebecca Summerfield, Dan Sykes (Natural History Museum, London, UK) and Roger Close (University of Oxford, Oxford, UK) for assistance with CT scanning. Jesús Alvarado-Ortega (Instituto de Geología, Universidad Nacional Autónoma de México, Coyoacán, Mexico), Christian Lemzaouda (CNRS-Muséum national d'Histoire naturelle, Paris, France), Olga Otero (Université de Poitiers, Poitiers, France) and Rivka Rabinovich (The Hebrew University of Jerusalem, Jerusalem, Israel) kindly provided specimen photographs. Research was supported by the Leverhulme Trust (RPG-2012-658, M. F. & D. J. D.; Philip Leverhulme Prize, M. F.) and ATM 'Formes possibles, formes réalisées' (Muséum national d'Histoire naturelle, D. D.). Finally we wish to thank Giorgio Carnevale and Alison Murray for their comments and feedback, which greatly improved an earlier version of the manuscript.

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<figure><img src="image_2.png" /><figcaption>**Figure 1.** †*Aipichthys pretiosus*, holotype NHMW 1857. XXXVIII. 7. **A**, specimen photograph (photograph by M. Friedman). **B**, interpretative drawing. Light grey diagonal hatching in **B** indicates damaged areas that could not be interpreted. Scale bar represents 10mm.</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**Figure 2.** Cranial and pectoral anatomy of †*Aipichthys pretiosus*, holotype NHMW 1857. XXXVIII. 7. **A**, specimen photograph (photograph by M. Friedman). **B**, interpretative drawing. Light grey diagonal hatching in **B** indicates damaged areas that could not be interpreted. Scale bar represents 10mm.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>**Figure 3.** Caudal anatomy of †*Aipichthys pretiosus*, holotype NHMW 1857. XXXVIII. 7. **A**, specimen photograph (photograph by M. Friedman). **B**, interpretative drawing. In **B**, fin rays are shown in light grey. Arrows indicate the first principal ray in the upper and lower parts of the fin. Scale bar represents 5mm.</figcaption></figure>
<figure><img src="image_5.png" /><figcaption>**Figure 4.** *Aipichthys* 'nuchalis, holotype NHMUK PV OR 25770 A, specimen photograph (photograph by M. Friedman). B, interpretative drawing. Light grey shading in B indicates damaged areas that could not be interpreted. Scale bar represents 5mm.</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>**Figure 5.** †'Aipichthys' nuchalis, holotype NHMUK PV OR 25770. A, computed tomography scan in left lateral view (virtual reconstruction by D. J. Delbarre). B, interpretative drawing. Light grey shading in B indicates damaged areas that could not be interpreted. Scale bar represents 5mm.</figcaption></figure>
<figure><img src="image_7.png" /></figure>

A

<figure><img src="image_8.png" /></figure>

B

**Figure 6.** Cranial anatomy of †*Aipichthys* *nuchalis*, holotype NHMUK PV OR 25770. **A**, computed tomography scan in left lateral view (virtual reconstruction by D. J. Delbarre). **B**, interpretative drawing. Light grey shading in **B** indicates damaged areas that could not be interpreted. Scale bar represents 5mm.

<figure><img src="image_9.png" /></figure>

A

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B

**Figure 7.** Pelvic bones of †*Aipichthys* *nuchalis*, holotype NHMUK PV OR 25770. **A**, computed tomography scan in ventral view (virtual reconstruction by D. J. Delbarre). **B**, interpretative drawing. Scale bar represents 1mm.
<figure><img src="image_11.png" /><figcaption>**Figure 8.** Strict consensus of 29 parsimonious trees. Tree length = 183, consistency index = 0.45, homoplasy index = 0.55, retention index = 0.70, rescaled consistency index = 0.31. Bremer indexes are above the branches, bootstrap indexes are below. Letters below branches are clade names. Clades with Greek letters as names are new. All other clades are from Davesne *et al.* (2014).</figcaption></figure>
<figure><img src="image_12.png" /><figcaption>**Figure 9.** A, †*Paraipichthys lusitanicus*, IST 561 (holotype). B, cf. †*Paraipichthys lusitanicus*, IST 560 (paratype of †*P. lusitanicus*). Photographs by D. Davesne. Scale bar represents 10mm.</figcaption></figure>

<figure><img src="image_13.png" /><figcaption>**Figure 10.** Specimen photograph of †*Gigapteryx tethyestris*, holotype NHMUK P. 62521 (photograph by D. J. Delbarre). Scale bar represents 10mm.</figcaption></figure>
<figure><img src="image_14.png" /><figcaption>**Figure 11.** Specimen photograph of †*Nardovelifer altipinnis*, holotype MSNV Na 519 (photographs by M. Friedman). This specimen is split into a number of pieces. Individual photographs of these pieces were digitally re-aligned to produce this figure. Scale bar represents 50mm.</figcaption></figure>
<figure><img src="image_15.png" /><figcaption>**Figure 12.** Other Cretaceous lampridomorphs. **A**, †*Pycnosteroides levispinosus*, MNHN. F. HDJ105 (photograph by C. Lemzaouda). **B**, †*Pharmacichthys numismalis*, holotype MNHN. F. HAK3 (photograph by C. Lemzaouda). **C**, †*Pharmacichthys venenifer*, NHMUK P. 62777 (photograph by D. J. Delbarre). **D**, †‘*Aipichthys’ minor*, MNHN. F. HAK94 (photograph by C. Lemzaouda). **E**, †‘*Aipichthys’ velifer*, MNHN. F. HAK57 (photograph by D. Davesne). **F**, †*Freigichthys elleipsis*, holotype FSL 573 015 (photograph by N. Podevigne, courtesy of O. Otero). **G**, †*Zoqueichthys carolinae*, holotype IHNFG-2224 (photograph by L. P. C. Machado, courtesy of J. Alvarado-Ortega). **H**, †*Aipichthyoides galeatus*, holotype EY 59a (photograph by Rivka Rabinovich). **I**, †*Aspesaipichthys cavaensis*, holotype MSNV Na 508 (photograph by M. Friedman). All scale bars represent 10mm.</figcaption></figure>