A Review of Mesozoic Acanthopterygian Fishes, with Special Reference to Those of the English Chalk
Abstract
Acid preparation of fishes from the English Chalk allows very detailed descriptions to be prepared. The acanthopterygians of the English Chalk are redescribed, and members of all the genera known by more than one specimen are treated at length. The English Chalk genera of Ctenothrissiformes, a group confined to the Cenomanian and Lower Turonian, are also described in detail, since this group is often cited as possibly ancestral to the acanthopterygians. The acanthopterygians and Ctenothrissiformes of all other Mesozoic deposits are more briefly described. The main systematic conclusions are as follows. A new order Ctenothrissiformes is made, to replace the Bathyclupeiformes, since Bathyclupea is a percoid. Within the Ctenothrissiformes, a new family Aulolepidae is made to contain Aulolepis and Pateroperca (the latter was formerly thought to be a percoid). The order Beryciformes is divided into three new sub-orders, Polymixioidei, Dinopterygoidei and Berycoidei. The Polymixioidei contains two families, the Polymixiidae, ranging from the Cenomanian to the present, and a new monotypic family Sphenocephalidae, confined to the Upper Senonian. The family Berycopsidae is rejected, and Berycopsis is placed in the Polymixiidae. Platycormus is shown to be a synonym of Berycopsis. The Dinopterygoidei contains the Upper Senonian Dinopterygidae and three new monotypic families, the Aipichthyidae, Pharmacichthyidae and Pycnosteroididae, all of which are confined to the Cenomanian. The Berycoidei contains eleven families, all with living representatives, of which only the Trachichthyidae and Holocentridae are present in the Mesozoic. A new genus of Trachichthyidae, Tubantia, from the Upper Senonian of Westphalia, is made. The genus Hoplopteryx, previously placed in the Berycidae, is shown to be a trachichthyid, and two new species of Hoplopteryx, H. macranthus and H. gephyrognathus, both from the English Chalk, are described. Among the Perciformes, a new genus of Serranidae, Proserranus, is made for a species from the Danian of Sweden, and Bathysoma, from the same horizon and locality, is shown to be a member of the Menidae. The genus Protobrama, previously thought to be a percoid, is shown to be a member of the Tselfatiidae (Beloniformes). It is suggested that Protriacanthus, previously placed in the perciform sub-order Balistoidei, may be related to the Aulostomiformes. The main phylogenetic and stratigraphic conclusions are as follows. An analysis of the characters of acanthopterygians shows that two main trends have operated during the evolution of the group, one associated with increased manoeuvrability, and the other with changed methods of feeding. It is shown that there has been a simplification of the structure of the pars jugularis of the trigeminofacialis chamber during the evolution of the acanthopterygians from primitive teleosts. The fin spines of acanthopterygians are found to be modified lepidotrichia, not fulcral scales, but an asymmetrical structure at the base of the first ray in both the pectoral and pelvic fins of the most primitive teleosts and in the pelvic fins of several generalized groups is possibly a fulcral scale. Acanthopterygians first appear at the base of the Cenomanian. After a radiation of the Beryciformes at or before the base of the Cenomanian the acanthopterygians remained almost constant in number throughout the Cenomanian, Turonian and Senonian. Not until the Perciformes appeared did they begin to radiate into the great range of forms found today. All the acanthopterygians of the Cenomanian, Turonian and Senonian are members of the Beryciformes, and all three sub-orders of Beryciformes are already present at the base of the Cenomanian. It is suggested that the Beryciformes may be at least a diphyletic group, with the Berycoidei having an origin independent of the other two sub-orders. It is concluded that the Beryciformes arose from near the Ctenothrissiformes, but from none of the known members of this group. The two Mesozoic families of Berycoidei, the Trachichthyidae and Holocentridae, show signs of convergence towards a common type as they are traced back to the base of the Cenomanian. The Trachichthyidae appear to be ancestral to all the families of Berycoidei except the Holocentridae. Within the Cretaceous Polymixiidae there are two diverging lines, one leading to the living Polymixia and the other leading to Berycopsis, which shows marked similarities to the perciform families Scorpidae, Monodactylidae and Kyphosidae. The other family of Polymixiodei, the Sphenocephalidae, is the only known group which could be ancestral to the Serranidae, the most generalized family of Perciformes. Each of the four families of Dinopterygoidei shows resemblances to a different group of Perciformes. The Dinopterygidae, so far as they are known, resemble the Centrarchidae, the Pycnosteroididae resemble the Chaetodontidae, the Aipichthyidae show marked similarities to the Carangidae, and the Pharmacichthyidae resemble the Acanthuroidei and Balistoidei. The Perciformes appear only in the uppermost Cretaceous, where two genera are known in the Danian and one in the Montian. Six different families of Cretaceous Beryciformes show similarities to different groups of Perciformes. It is found that there is no good evidence for regarding all these similarities as due to convergence, but that some of them, and in particular those between the Aipichthyidae and Carangidae and between Berycopsis and the Scorpidae, indicate relationship. It is therefore suggested that the Perciformes is a polyphylectic group, in which several lines arose independently at a beryciform level.
- Publication:
-
Philosophical Transactions of the Royal Society of London Series B
- Pub Date:
- July 1964
- DOI:
- 10.1098/rstb.1964.0003
- Bibcode:
- 1964RSPTB.247..213P